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  • 101.
    Palmberg, Robin C. O.
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Susilo, Yusak O.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Developing and Trialling an Implicit Interaction Platform to Monitor Elderly TravellersManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    As the population grows older, age-induced illnesses related to cognitive impairments arise. Little is known regarding what and how the built environment affects that target group. It is theorized that external factors in the built environment might play a part in elderlies getting lost because of conditions related to illnesses such as dementia. To accommodate the target group in a future society, it is crucial to understand any possible correlation between locations and psychophysiological conditions.

    Technological advancements of wearable devices allow for the creation of software that collects data relevant to location as well as biometric data automatically, without affecting the user. By utilising consumer-grade hardware, it is possible to scale up the studies that the software allows for indefinitely.

    This paper covers the development of such a tool, by detailing what has become possible because of previous advancements in research regarding automatic travel diaries and the recognition of psychophysiological conditions through biometric data collection. Initial testing shows, that while data can be collected as proposed, there are drawbacks in terms of run time due to the battery capacity of wearable devices. More data is required to indicate whether the data collected can be used for correlation and causality analysis.

  • 102.
    Palmberg, Robin C. O.
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Susilo, Yusak O.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Naqavi, Fatemeh
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Built Environment Characteristics, Daily Travel, and Biometric Readings: Creation of an Experimental Tool based on a Smartwatch PlatformManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The utilisation of travel surveys can uncover layers of information regarding travel behaviour, travel needs, and more. The collected information is utilised to make strategic planning choices when reorganising or planning new built environments. Over the years, the methods for conducting travel surveys have changed from manual interviews and paper forms to automated travel diaries which are monitoring the trips made by the survey participants. With the fast progression of technological advancements, new possibilities for operationalising said types of automated travel diaries can be changed from utilising mobile devices to wearable devices. Wearable devices are often equipped with sensors which can collect continuous biometric data from sources which are not reachable from standard mobile devices such as smartphones. The biometric data that can be collected through wearable devices ranging from heart rate and blood pressure to temperature and perspiration, given the proper sensors. This advancement opens for new possible layers of information in the collection of travel data. Such biometric data can be used to derive psychophysiological conditions related to cognitive load, which can uncover more in-depth knowledge regarding stress and emotions, given the right variables and sample rate. This paper aims to explore the possibilities in terms of data analysis on a data set collected through a software combining traditional travel survey data, such as position and time, with biometric data, in this case; heartrate, to gain knowledge of the implications of such collected data. The knowledge about the implications of spatial configurations can be used in the planning phase of new areas, in order to create more accessible environments, as the information could be used to make neutral, or even encouraging, environments for travellers.

  • 103.
    Palmberg, Robin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Susilo, Yusak
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för trafikforskning, CTR. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Enabling Technologies to Serve the Ageing Urban Society Better (ENTRUST)2018Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The life span of the inhabitants of Sweden is increasing and with this comes age related cognitive diseases such as those related to dementia. Our society is not prepared to accommodate for the needs of the people who are affected by this.

    The diseases related to dementia often affect the person’s ability to localize themselves and to remember previous and upcoming events. A common issue that occurs is a state called “elopement”.

  • 104.
    Palmberg, Robin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Susilo, Yusak
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för trafikforskning, CTR. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Developing and trialling an implicit interaction platform to monitor and aiding dementia travellers2019Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Age related cognitive diseases are becoming a growing problem in Sweden. With the fast ageing population and lowered mortality rate comes the spread of cognitive diseases related to dementia. In order to accommodate this growing target group in transport and the built environment, it is important to understand the mobility and travel behaviour of patients suffering from these diseases. One subset of this target group is travellers suffering from age induced illnesses related with dementia, which most often have fluctuating symptoms that are affecting the cognitive skills of the traveller. This makes it hard to use standardized forms and survey-based information that would require the traveller to actively respond retroactively, either in oral or written form, since the traveller might have forgotten or mixed up their past experiences, among other things, it becomes very hard to gain confidence in the results as it might be hard to tell in which condition the patient is during the collection.

    We propose an automated collection of biometric data such as heart rate in combination with position. Since the validity of the information collected in this manner is directly related to the quality of the sensors used it means that the precision and accuracy of the results could be virtually endlessly improved by upgrading the hardware and optimizing the software. To take a first step towards a solution like this we have started developing a smart watch application which is utilizing PPG technology to collect heart rate and combine it with positions collected through GPS technology.

    Early testing has shown the possibility to correlate the heart rate of a traveller to their specific location. The implications of this must be validated through data labelling as we wish to utilize machine learning algorithms to analyse the data collected.

  • 105.
    Palmberg, Robin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Susilo, Yusak
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för trafikforskning, CTR.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Uncovering Effects of Spatial and Transportation Elements on Travellers Using Biometric Data2019Inngår i: TOWARDS HUMAN SCALE CITIES - OPEN AND HAPPY / [ed] Tuuli Toivonen, Karst Geurs, Elias Willberg, Helsinki: Department of Geosciences and Geography, University of Helsinki , 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Travel surveys has been used for decades to observe the patterns, locations, and choices, which travellers chose and do during the given observed period. This information can be utilized as background for informed planning decisions. Despite the progress in the travel survey technologies, the applications mostly focus on more traditional travel parameters. With programmable smart watches now, we can also collect real time data that is not solely pertaining to position and travel mode choices, but also to users’ biometric data. Such an application would open another level of possibilities in dynamically integrating land use and transport planning with public health research.

    Utilising a smart watch platform, we are aiming to develop a tool that will collect biometric data, in combination with spatial context, such as position, spatial features and objects in the built environment, and by utilizing machine learning algorithms, try to detect how travellers are affected by their choice of transport mode, the built environment in general as well as how the public transport is operated.

    Early testing reveals the possibility to find correlations between heart rate and position, which in turn could reveal the effect of spatial and transportation elements on the traveller. By targeting widely available hardware, the scalability for this tool is virtually endless, making it possible to collect large amounts of data and utilizing machine learning algorithms to analyse it.

  • 106.
    Plynning, Emil
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Route planning using multiple attributes: Finding routes other than the shortest for bicycles2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Congestion and pollution are two ever increasing problems in our would of urbanization. Bicycling is one of the most sustainable means of transport and it is a great way of reducing congestion in cities. Route planners which brings out the best aspects of bicycling and promotes them during route calculation is a good way of increasing the attractiveness of bicycling.

    When planning a route today there are online services which can perform regular route planning taking only the length of each route into consideration. The objective of this paper is to introduce an alternative way of performing route planning using other traits than just the length when determining the best route.

    This paper introduces an algorithm which is able to perform route planning which takes several aspects into account. The algorithm uses two additional attributes together with the length to determine the cost of traversing each polyline. The additional attributes used are named nature and slope index. The nature index is supposed to give a numerical representation of the environment surrounding the polyline, this is calculated using a land cover map and a buffer around each polyline which represents its neighborhood. The nature index is used to make the route planner prefer more beautiful paths along water, park or forests over shorter ones which passes through high density development for instance. The slope index is stores the average slope of the entire polyline. It is calculated using a digital elevation model and dividing the height difference between the start and end point with the length resulting in a slope percentage. The slope index is used to find paths which are as flat as possible.

     

    The two indexes together with the length attribute are then combined in seven different cost functions, each weighting the attributes differently to accommodate different preferences. Each of the calculated costs is stored as an attribute for every polyline. Networks on which route planning can be performed are then built using these cost attributes.

    The resulting networks are inspected visually using the indexes as display factors and determined to be accurate. Route planning using these networks results routes do follow areas with higher nature index and avoids slopes. In this paper a few examples of routes with an orthophoto as background are included which clearly illustrates that the nature index promotes the correct type of environment.

  • 107.
    Prelipcean, Adrian Corneliu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Susilo, Yusak
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap.
    MEILI: A travel diary collection, annotation and automation system2018Inngår i: Computers, Environment and Urban Systems, ISSN 0198-9715, E-ISSN 1873-7587, Vol. 70, nr July 2018, s. 24-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The increased interest in the automation of travel diary collection, together with the ease of access to new artificial intelligence methods led scientists to explore the prerequisites to the automatic generation of travel diaries. One of the most promising methods for this automation relies on collecting GPS traces of multiple users over a period of time, followed by asking the users to annotate their collected data by specifying the base entities for a travel diary, i.e., trips and triplegs. This led scientist on one of two paths: either develop an in-house solution for data collection and annotation, which is usually an undocumented prototype implementation limited to few users, or contract an external provider for the development, which results in additional costs. This paper provides a third path: an open-source highly modular system for the collection and annotation of travel diaries of multiple users, named MEILI. The paper discusses the architecture of MEILI with an emphasis on the data model, which allows scientists to implement and evaluate their methods of choice for the detection of the following entities: trip start/end, trip destination, trip purpose, tripleg start/end, and tripleg mode. Furthermore, the open source nature of MEILI allows scientists to modify the MEILI solution in compliance with their legal and ethical specifications. MEILI was successfully trialed in multiple case studies in Stockholm and Gothenburg, Sweden between 2014 and 2017.

    Fulltekst tilgjengelig fra 2020-02-04 13:09
  • 108.
    Prelipcean, Adrian Corneliu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och geoinformatik. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Susilo, Yusak
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Transportation mode detection – an in-depth review of applicability and reliability2016Inngår i: Transport reviews, ISSN 0144-1647, E-ISSN 1464-5327Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The wide adoption of location-enabled devices, together with the acceptance of services that leverage (personal) data as payment, allows scientists to push through some of the previous barriers imposed by data insufficiency, ethics and privacy skepticism. The research problems whose study require hard-to-obtain data (e.g. transportation mode detection, service contextualisation, etc.) have now become more accessible to scientists because of the availability of data collecting outlets. One such problem is the detection of a user's transportation mode. Different fields have approached the problem of transportation mode detection with different aims: Location-Based Services (LBS) is a field that focuses on understanding the transportation mode in real-time, Transportation Science is a field that focuses on measuring the daily travel patterns of individuals or groups of individuals, and Human Geography is a field that focuses on enriching a trajectory by adding domain-specific semantics. While different fields providing solutions to the same problem could be viewed as a positive outcome, it is difficult to compare these solutions because the reported performance indicators depend on the type of approach and its aim (e.g. the real-time availability of LBS requires the performance to be computed on each classified location). The contributions of this paper are three fold. First, the paper reviews the critical aspects desired by each research field when providing solutions to the transportation mode detection problem. Second, it proposes three dimensions that separate three branches of science based on their main interest. Finally, it identifies important gaps in research and future directions, that is, proposing: widely accepted error measures meaningful for all disciplines, methods robust to new data sets and a benchmark data set for performance validation.

  • 109.
    Prelipcean, Adrian Corneliu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och geoinformatik. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Susilo, Yusak Octavius
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Systemanalys och ekonomi.
    Longest common subsequences: Identifying the stability of individuals’ travel patternsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    There is a strong consensus in the travel behaviour research community that the one day travel diary collection is insufficient to understand the finer aspects of behaviour that transcend attributes such as average trip length, duration, travel modes, etc. While a large body research was done on exploring the spatial, temporal and spatio-temporal travel behavioural patterns, the sequential aspect of behaviour is seldom studied. The consensus of the few papers that have studied travel behaviour variability from a sequential perspective has been to use edit distance and compute the costs of transforming one day of travel activities into another. While useful, this approach generates difficult to understand metrics since it does not directly extract (sub)sequences but computes penalties. This paper provides an alternative for investigating the sequential aspect of travel behaviour that makes use of longest common subsequences to extract the activities that are common to multiple days and / or users. The proposed methodology provides indexes for measuring the inter- and intra-personal stability of a given user base and its usefulness is proved in a case study on travel diaries collected from 51 users for a period of 7 days.

  • 110.
    Prelipcean, Adrian Corneliu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö.
    Susilo, Yusak
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Collecting travel diaries: Current state of the art, best practices, and future research directions2018Inngår i: Transport Survey Methods in the era of big data: facing the challenges, Elsevier, 2018, Vol. 32, s. 155-166Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The amount of useful information that can be extracted from travel diaries is matched by the difficulty of obtaining travel diaries in a modern era where the response rate to traditional travel diary collection methods has seen a decrease in most countries. Prompted by this, a body of research has been dedicated to study how travel diaries can be collected via new methods, namely location enabled devices such as smartphones, that have a higher penetration rate (in terms of device ownerships and user attachment) and are both easier and cheaper to manage compared to traditional data collection method, e.g. paper-and-pencil, phone, or web-based questionnaires. This paper offers an overview of the current state of travel diary collection, a potential future state and a practical checklist for travel diary collection case studies. A thorough discussion on different pros and cons of travel diary collection methods and efforts needed for the convergence of methods to collect travel diaries for all demographics are provided. The practical checklist to aid researchers to organise case studies is based on the authors' experience and it is meant to raise awareness of difficulties that can be encountered while collecting travel surveys with automated and semi-automated systems, and how to overcome them.

  • 111.
    Prelipcean, Adrian Corneliu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Susilo, Yusak Octavius
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Systemanalys och ekonomi.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och geoinformatik. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    A series of three case studies on the semi-automation of activity travel diary generation using smarpthones2017Inngår i: Proceedings of TRB 2017 Annual Meeting, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The growing need of acquiring data that is useful for travel behaviour analysis led scientists topursue new ways of obtaining travel diaries from large groups of people. The most promising al-ternative to traditional (declarative) travel diary collection methods are those that rely on collectingtrajectories from individuals and then extract travel diary semantics from the trajectories. However,most studies report on routines specific to the post-processing of data, and seldom focus on datacollection. Even the few studies that deal explicitly with data collection describe the final state ofthe collection system, but do not go at the lengths that are required to describe the decision thatwere taken to bring the system to its current state. This leads to a considerable amount of work thatis needed for designing collection systems that are often undocumented, which impedes the reuseof the aforementioned systems. In light of the aforementioned problems, this paper presents a series of three case studies behind the continuous development of MEILI, a travel diary collection,annotation and automation system, in an effort to: 1) illustrate the utility of the developed systemto collect travel diaries, 2) identify how MEILI and other semi-automatic travel diaries collectionsystems can be improved, and 3) propose MEILI as an open source system that has the potentialof being improved into a widely available semi-automated travel diary collection system.

  • 112.
    Prelipcean, Adrian Corneliu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    Susilo, Yusak Octavius
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Systemanalys och ekonomi.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och geoinformatik. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Future directions of research for automatic travel diary collection2018Inngår i: Proceedings of the 11th International conference on Transport Survey Methods, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The amount of useful information that can be extracted from travel diaries is matched by the difficulty of obtaining travel diariesin a modern era where the response rate to traditional travel diary collection methods has seen a decrease in most countries.Prompted by this, a body of research has been dedicated to study how travel diaries can be collected via new methods, namelylocation enabled devices such as smartphones, that have a higher penetration rate (in terms of device ownerships and userattachment) and are both easier and cheaper to manage compared to traditional data collection method, e.g. paper-and-pencil,phone, or web-based questionnaires. This paper offers an overview of the current state of travel diary collection, a potentialfuture state and a practical checklist for travel diary collection case studies. A thorough discussion on different pros and cons oftravel diary collection methods and efforts needed for the convergence of methods to collect travel diaries for all demographicsare provided. The practical checklist to aid researchers to organise case studies is based on the authors’ experience and it is meantto raise awareness of difficulties that can be encountered while collecting travel surveys with automated and semi-automatedsystems, and how to overcome them.

  • 113.
    Prelipcean, Adrian Corneliu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Yamamoto, Toshiyuki
    Nagoya Univ, Inst Mat & Syst Sustainabil, Chikusa Ku, Furo Cho, Nagoya, Aichi 4648603, Japan..
    Workshop Synthesis: New developments in travel diary collection systems based on smartphones and GPS receivers2018Inngår i: TRANSPORT SURVEY METHODS IN THE ERA OF BIG DATA: FACING THE CHALLENGES / [ed] Bonnel, P Munizaga, M Morency, C Trepanier, M, ELSEVIER SCIENCE BV , 2018, s. 119-125Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This workshop examined the state of the art of existing travel diary collection systems that make use of GPS data in relation to the needs of the practitioners that collect and analyze travel diaries. While the new data collection methods are a promising alternative that can collect both data on previously ignored demographic segments as well as short trips that are usually forgotten by respondents, they do not solve all the issues the traditional methods are prone to, and also introduce new issues of their own. The workshop participants have identified, discussed and summarized the most pressing concerns regarding the use of new travel diary collection systems based on smartphones and GPS receivers.

  • 114.
    Prelipcean, Adrian
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Gidófalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Susilo, Yusak
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transportplanering, ekonomi och teknik.
    Comparative framework for activity-travel diary collection systems2015Inngår i: 2015 International Conference on Models and Technologies for Intelligent Transportation Systems, MT-ITS 2015, IEEE conference proceedings, 2015, s. 251-258Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The needs for cheaper and less intrusive ways to collect activity-travel diaries led scientist to pursue new technologies, e.g., positioning technologies like GPS. While a fully, reliable and widely accepted automatic activity-travel diary collection system is yet to be developed, scientists have presented systems that automate parts of an activity-travel diary collection. In the advent of automated systems, it is important to discuss how to analyse the potential of such systems and how to compare different activity-travel diary collection systems. To achieve this objective, this paper introduces a parallel survey design and a comparison framework for collection systems. The framework can be used as a development tool to optimise system design, to report and monitor progress of different system designs, to objectively weigh benefits in decision making, and to automate systematic analysis. In particular, the framework can be used as a comparison tool to reveal the qualitative difference in the data gathered using different collection systems. To achieve this, the framework defines: 1) a number of activity-travel diary measurement entities (trips and triplegs), entity attributes (e.g., trip purpose, origin / destination, etc.), 2) similarity functions between instances of the same entities, and 3) spatial and temporal quality indices to establish a notion of ground truth. The utility of the proposed framework is demonstrated by analysing the results of a trial survey where data is collected via two activity-travel collection systems: a web-based system (PP) and a smartphone-app-based system (MEILI). PP was collected for one day period and MEILI was used for one week period (with one day overlapping). The results show that half of the trips are captured by both systems, while each system roughly captures the same number of trips as the other. The strengths and weaknesses of MEILI are analysed using the framework on the entire week dataset.

  • 115.
    Qin, Yuchu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö.
    Li, Shihua
    Vu, Tuong-Thuy
    Niu, Zheng
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Synergistic application of geometric and radiometric features of LiDAR data for urban land cover mapping2015Inngår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 23, nr 11, s. 13761-13775Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Urban land cover map is essential for urban planning, environmental studies and management. This paper aims to demonstrate the potential of geometric and radiometric features derived from LiDAR waveform and point cloud data in urban land cover mapping with both parametric and non-parametric classification algorithms. Small footprint LiDAR waveform data acquired by RIEGL LMS-Q560 in Zhangye city, China is used in this study. A LiDAR processing chain is applied to perform waveform decomposition, range determination and radiometric characterization. With the synergic utilization of geometric and radiometric features derived from LiDAR data, urban land cover classification is then conducted using the Maximum Likelihood Classification (MLC), Support Vector Machines (SVM) and random forest algorithms. The results suggest that the random forest classifier achieved the most accurate result with overall classification accuracy of 91.82% and the kappa coefficient of 0.88. The overall accuracies of MLC and SVM are 84.02, and 88.48, respectively. The study suggest that the synergic utilization of geometric and radiometric features derived from LiDAR data can be efficiently used for urban land cover mapping, the non-parametric random forest classifier is a promising approach for the various features with different physical meanings.

  • 116.
    Qin, Yuchu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Yao, W.
    TU Munich.
    Vu, T.
    University of Nottingham, Malaysia.
    Li, S.
    China.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Characterizing radiometric attributes of point cloud using a normalized reflective factor derived from small footprint LiDAR waveform2015Inngår i: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 8, nr 2, s. 740-749, artikkel-id 6918370Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a reflectance-like coefficient, normalized reflective factor (NRF) to characterize the radiometric attributes of point cloud generated from small footprint light detection and ranging (LiDAR) waveform data. The NRF is defined as a normalized ratio between the energy of emitted laser beam and the peak in return waveform in conjunction with the atmospheric attenuation and observation geometry. Based on the Gaussian parameters of the emitted and return waveforms, NRF is calculated with an empirical atmospheric model and user-defined standard observation geometry. To correct the radiometric measurement of point cloud in multipeak waveform, a semi-physical-based method is adopted to enhance the NRF of point cloud generated from multipeak waveform. Experiments are conducted with small footprint LiDAR waveform data acquired by RIEGL LMS-Q560. A curve-fitting-based approach is applied to decompose LiDAR waveform into three-dimensional (3-D) coordinates of point cloud, and the NRF are calculated using the Gaussian parameters of both emitted and return waveforms. The visualization of the radiometric attributes of point cloud data is carried out over the overlapping areas between different flight strips, it suggests that the NRF over overlapping area is much smooth than the normalized intensity. Quantitative comparison with Hyperion data indicates that the NRF has much higher correlation with surface reflectance than the normalized intensity data. Standard deviations of NRF and the normalized intensity of different land cover patches are analyzed to assess the homogeneity of the radiometric data. It is observed that NRF has less variability than the normalized intensity within the same land cover patches. Point cloud of two sample trees is also selected to assess the performance of the “sub-footprint” effect correction. It is observed that the proposed approach reduced the variability of radiometric attributes over tree canopies with increa- ing NRF values; which means the “sub-footprint” effect is mitigated. In summary, the proposed NRF can serve as a promising indicator to characterize radiometric attribute of LiDAR point cloud.

  • 117. Ravanelli, R.
    et al.
    Nascetti, Andrea
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. Geodesy and Geomatics Division, DICEA—University of Rome La Sapienza, 00184 Rome, Italy.
    Cirigliano, R. V.
    Di Rico, C.
    Leuzzi, G.
    Monti, P.
    Crespi, M.
    Monitoring the impact of land cover change on surface urban heat island through Google Earth Engine: Proposal of a global methodology, first applications and problems2018Inngår i: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 10, nr 9, artikkel-id 1488Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    All over the world, the rapid urbanization process is challenging the sustainable development of our cities. In 2015, the United Nation highlighted in Goal 11 of the SDGs (Sustainable Development Goals) the importance to "Make cities inclusive, safe, resilient and sustainable". In order to monitor progress regarding SDG 11, there is a need for proper indicators, representing different aspects of city conditions, obviously including the Land Cover (LC) changes and the urban climate with its most distinct feature, the Urban Heat Island (UHI). One of the aspects of UHI is the Surface Urban Heat Island (SUHI), which has been investigated through airborne and satellite remote sensing over many years. The purpose of this work is to show the present potential of Google Earth Engine (GEE) to process the huge and continuously increasing free satellite Earth Observation (EO) Big Data for long-term and wide spatio-temporal monitoring of SUHI and its connection with LC changes. A large-scale spatio-temporal procedure was implemented under GEE, also benefiting from the already established Climate Engine (CE) tool to extract the Land Surface Temperature (LST) from Landsat imagery and the simple indicator Detrended Rate Matrix was introduced to globally represent the net effect of LC changes on SUHI. The implemented procedure was successfully applied to six metropolitan areas in the U.S., and a general increasing of SUHI due to urban growth was clearly highlighted. As a matter of fact, GEE indeed allowed us to process more than 6000 Landsat images acquired over the period 1992-2011, performing a long-term and wide spatio-temporal study on SUHI vs. LC change monitoring. The present feasibility of the proposed procedure and the encouraging obtained results, although preliminary and requiring further investigations (calibration problems related to LST determination from Landsat imagery were evidenced), pave the way for a possible global service on SUHI monitoring, able to supply valuable indications to address an increasingly sustainable urban planning of our cities. 

  • 118. Ravanelli, R.
    et al.
    Nascetti, Andrea
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. University of Rome La Sapienza, Rome, Italy.
    Cirigliano, R. V.
    Di Rico, C.
    Monti, P.
    Crespi, M.
    Monitoring urban heat island through google earth engine: Potentialities and difficulties in different cities of the United States2018Inngår i: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives, International Society for Photogrammetry and Remote Sensing , 2018, Vol. 42, nr 3, s. 1467-1472Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this work is to exploit the large-scale analysis capabilities of the innovative Google Earth Engine platform in order to investigate the temporal variations of the Urban Heat Island phenomenon as a whole. A intuitive methodology implementing a large-scale correlation analysis between the Land Surface Temperature and Land Cover alterations was thus developed. The results obtained for the Phoenix MA are promising and show how the urbanization heavily affects the magnitude of the UHI effects with significant increases in LST. The proposed methodology is therefore able to efficiently monitor the UHI phenomenon.

  • 119.
    Ravanelli, Roberta
    et al.
    DICEA Univ Rome La Sapienza, Geodesy & Geomat Div, Rome, Italy..
    Lastilla, Lorenzo
    DICEA Univ Rome La Sapienza, Geodesy & Geomat Div, Rome, Italy..
    Nascetti, Andrea
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. DICEA Univ Rome La Sapienza, Geodesy & Geomat Div, Rome, Italy..
    Di Rita, Martina
    DICEA Univ Rome La Sapienza, Geodesy & Geomat Div, Rome, Italy..
    Nigro, Lorenzo
    Univ Roma La Sapienza, Dept Oriental Studies, Archaeol Expedit Motya, Rome, Italy..
    Montanari, Daria
    Univ Roma La Sapienza, Dept Oriental Studies, Archaeol Expedit Motya, Rome, Italy..
    Spagnoli, Federica
    Univ Roma La Sapienza, Dept Oriental Studies, Archaeol Expedit Motya, Rome, Italy..
    Crespi, Mattia
    DICEA Univ Rome La Sapienza, Geodesy & Geomat Div, Rome, Italy..
    3D modelling of archaeological small finds by the structure sensor range camera: comparison of different scanning applications2018Inngår i: APPLIED GEOMATICS, ISSN 1866-9298, Vol. 10, nr 4, s. 399-413Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Today, range cameras represent a cheap, intuitive and effective technology for collecting the 3D geometry of objects and environments automatically and practically in real time. Such features can make these sensors a valuable tool for documenting archaeological small finds, especially when not expert users are involved. Therefore, in this work, Scanner and itSeez3D, two of the most promising scanning applications actually available for the Structure Sensor, a range camera specifically designed for mobile devices, were tested in order to evaluate their accuracy in modelling the 3D geometry of two archaeological artefacts, characterized by different shape and dimensions. The 3D models obtained through the two scanning applications were thus compared with the reference ones generated with the more accurate photogrammetric technique. The results demonstrate that both the applications show the same level of geometric accuracy, which amounts generally to very few millimetres, from an overall point of view, and, at the same time, they substantially point out the good quality of the Structure Sensor 3D reconstruction technology. In particular, the itSeez3D application is surely the best solution for the color restitution, even if it requires a payment of $7 to export and thus to use effectively each model generated. On the other side, Scanner is a free application and its geometric accuracy is comparable to that of itSeez3D, but, however, the colours are frequently smoothed and sometimes not fully rendered.

  • 120. Routh, D.
    et al.
    Seegmiller, Lindsi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Bettigole, C.
    Kuhn, C.
    Oliver, C. D.
    Glick, H. B.
    Improving the reliability of mixture tuned matched filtering remote sensing classification results using supervised learning algorithms and cross-validation2018Inngår i: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 10, nr 11, artikkel-id 1675Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mixture tuned matched filtering (MTMF) image classification capitalizes on the increasing spectral and spatial resolutions of available hyperspectral image data to identify the presence, and potentially the abundance, of a given cover type or endmember. Previous studies using MTMF have relied on extensive user input to obtain a reliable classification. In this study, we expand the traditional MTMF classification by using a selection of supervised learning algorithms with rigorous cross-validation. Our approach removes the need for subjective user input to finalize the classification, ultimately enhancing replicability and reliability of the results. We illustrate this approach with an MTMF classification case study focused on leafy spurge (Euphorbia esula), an invasive forb in Western North America, using free 30-m hyperspectral data from the National Aeronautics and Space Administration's (NASA) Hyperion sensor. Our protocol shows for our data, a potential overall accuracy inflation between 18.4% and 30.8% without cross-validation and according to the supervised learning algorithm used. We propose this new protocol as a final step for the MTMF classification algorithm and suggest future researchers report a greater suite of accuracy statistics to affirm their classifications' underlying efficacies.

  • 121.
    Rui, Yikang
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. Nanjing University, China.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Exploring the relationship between street centrality and land use in Stockholm2014Inngår i: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 28, nr 7, s. 1425-1438Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper examines the relationship between different street centralities and land-use types in Stockholm. Major centrality measures of closeness, betweenness, and straightness are calculated at both global and local levels in both the primary and dual representations of the urban street network. Adaptive kernel density estimation is adopted to transform all unevenly distributed datasets to one continuous raster framework for further analysis. After computing statistical and spatial distribution of each centrality and land-use density map, we find that the density of each street centrality is highly correlated with one type of land use. Results imply that various centralities representing street properties from different aspects can capture the land development patterns of different land-use types by reflecting human activities, and are consequently important indicators to describe urban structure.

  • 122.
    Saqib, Ehsan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Anonymous Mobile Consumer Analysis Platform2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Advances in mobile communication, computing and positioning technologies allow the real-time acquisition of continuously changing locations of moving objects, e.g., users carrying location-aware mobile devices. The geocontextual analysis of these locations of users can reveal valuable mobile consumer patterns and enable a number of promising Business Intelligence (BI) services and desirable intelligent Location-Based Services (LBSes). However, as some exact user locations can be extremely sensitive while others can be used to link the users to his or her real-world identity, location traces of users must be anonymized.To facilitate these promising BI services and desirable intelligent LBS in a privacy preserving manner, the present paper proposes an Anonymous Mobile Consumer Analysis Platform (AMCAP) that based on the geocontextual analysis of anonymized location traces, in four phases, derives mobile consumer characteristics of its users in terms of Anomymous Mobile Consumer Profiles (AMCPs) and information about the dynamically changing spatio-temporal distribution of the users that is recorded in a spatio- temporal data warehouse of Anonymous Mobile Consumer Types (AMCTs). In the first phase, based on a number of spatio-temporal criteria the platform probabilistically associates a user’s generalized location, that is represented by an anonymization region with activity types that activity centers in the anonymization region can facilitate. In the second phase, based on the activity type inferred in phase one, the platform, in an online and incremental fashion, summarizes an Anonymous Mobile Consumer Profile (AMCP) for each of the users. In the third phase, the platform periodically groups the users based on their AMCPs into a number Anonymous Mobile Consumer Types (AMCTs). Finally, in the fourth phase, in order to capture the dynamically changing spatio-temporal distribution of the consumers and their characteristics, the platform, in an online and incremental fashion, records the frequency and duration of the visits of different AMCTs to different spatio-temporal regions.The AMCAP is empirically evaluated on the simulated movements of a subset of the population of Copenhagen, Denmark. Experiments regarding the accuracy of the AMCP construction reveal that the proposed activity type inference from anomymized regions is effective and can predict the actual activity of the users with an accuracy of 0.75 and a κ- value of 0.73. AMCPs are clustered into 7 AMCTs. The quality of AMCTs is evaluated by comparing it with Actual Consumer Types (ACTs) which are extracted from Actual Consumer Profiles (ACPs). In both the AMCPs and ACPs, the optimal number of clusters is 7. Meaning thereby that although AMCPs are blurred, they do not loose their inherent property of being clustered into the same of number of types as ACPs. The Adjusted Rand Index (ARI) (a measurement for similarity between two grouping of objects) between the AMCTs and ACTs is 0.3 which is significantly higher than the random assignment where ARI value is -0.0000247. Computational performance evaluations show that a relational DBMS-based prototype implementation of the AMCAP on a single machine can process 50,000 anonymization rectangles in 20 seconds. Based on the assumption that during any given 5-minute interval no more than 10% of the users submit an anonymization region, it is extrapolated that the prototype is capable to perform in real-time the geocontextual analysis (i.e., phases 1, 2, and 4) of anonymized location traces of 7 million users. Finally, to illustrate the utility of the information that is derived by the AMCAP a number of derived BI services are discussed.

  • 123. Shen, Jingwei
    et al.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Route Choice of the Shortest Travel Time Based on Floating Car Data2016Inngår i: Journal of Sensors, ISSN 1687-725X, E-ISSN 1687-7268, artikkel-id 7041653Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Finding a route with shortest travel time according to the traffic condition can help travelers to make better route choice decisions. In this paper, the shortest travel time based on FCD (floating car data) which is used to assess overall traffic conditions is proposed. To better fit FCD and road map, a new map matching algorithm which fully considers distance factor, direction factor, and accessibility factor is designed to map all GPS (Global Positioning System) points to roads. A mixed graph structure is constructed and a route analysis algorithm of shortest travel time which considers the dynamic edge weight is designed. By comparing with other map matching algorithms, the proposed method has a higher accuracy. The comparison results show that the shortest travel time path is longer than the shortest distance path, but it costs less traveling time. The implementation of the route choice based on the shortest travel time method can be used to guide people's travel by selecting the space-time dependent optimal path.

  • 124.
    Sheng, Nan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och satellitpositionering. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Prediction and 3D Visualization of Environmental Indicators: Noise and Air Pollution2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Environmental problems such as noise and air pollution are increasingly catching people’s attention in recent years owing to the industrialization and urbanization all over the world. Therefore it is important to develop effective methods to present information on noise and air pollution to the public. One feasible approach is to carry out prediction based on traffic data and make noise and pollution maps. GIS is a powerful tool for prediction since its spatial analysis function could be used in analysis and calculation. In addition the available GIS platforms also provide visualization functions to display the analysis results in variety of forms, in both 2D and 3D. This thesis uses noise and air pollution as examples to study how to predict noise and pollution from traffic data and how to visualize the predicted pollution information in 3D with the help of the existing visualization technology.

    Therefore, the thesis has two objectives. The first objective is focused on prediction of noise and air pollution using existing prediction models based on vehicle speed and traffic volume data. The original spatial road network dataset with traffic information was integrated with GIS and analysis and calculations were carried out. Road Traffic Noise-Nordic Prediction Method is used for predicting traffic noise while ARTEMIS model and OSPM model are applied for traffic air pollution. All analysis and calculations were carried out on virtual receiver points generated on ground surface and over building facades at different heights. The second objective is focused on 3D visualization of the predicted traffic noise and air pollution in ArcScene, Google Earth as well as X3D respectively. In ArcScene the virtual receiver points were visualized in their actual position with different colors representing noise or air pollution level. Then KML files were created from the point shapefiles and imported into Google Earth to show the noise and air pollution level in the virtual city available in Google Earth. Finally one layer of point shapefile was selected as an example to give the 3D scene in X3D. The selected layer of points was first interpolated into a continuous surface and converted into contours. Three types of models were developed in this part. First is to visualize contours in 3D using both colors and heights to show the noise or air pollution levels. Next the interpolated surface was segmented into scattered cells displayed also in colors and heights both representing pollution intensity. The last one is using 3D bars to show noise or air pollution in colors and lengths.

    The prediction results shows that the either noise or air pollution in the north part of central Stockholm is much more serious than in south part and the most polluted area appear along the highways. In the same area the pollution levels vary in different heights. The 3D visualization in ArcScene and Google Earth could clearly present the differences. However, so far the visualization in X3D only gives 2D information in 3D, which means although the 3D scenes were created, the height only noise or air pollution on the specific height could be represented. The real 3D representing is still need to be studied. 

  • 125.
    Shirabe, Takeshi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    A method for finding a least-cost wide path in raster space2016Inngår i: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 30, nr 8, s. 1469-1485Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Given a grid of cells each having an associated cost value, a raster version of the least-cost path problem seeks a sequence of cells connecting two specified cells such that its total accumulated cost is minimized. Identifying least-cost paths is one of the most basic functions of raster-based geographic information systems. Existing algorithms are useful if the path width is assumed to be zero or negligible compared to the cell size. This assumption, however, may not be valid in many real-world applications ranging from wildlife corridor planning to highway alignment. This paper presents a method to solve a raster-based least-cost path problem whose solution is a path having a specified width in terms of Euclidean distance (rather than by number of cells). Assuming that all cell values are positive, it does so by transforming the given grid into a graph such that each node represents a neighborhood of a certain form determined by the specified path width, and each arc represents a possible transition from one neighborhood to another. An existing shortest path algorithm is then applied to the graph. This method is highly efficient, as the number of nodes in the transformed graph is not more than the number of cells in the given grid and decreases with the specified path width. However, a shortcoming of this method is the possibility of generating a self-intersecting path which occurs only when the given grid has an extremely skewed distribution of cost values.

  • 126.
    Shirabe, Takeshi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Buffered or bundled, least-cost paths are not least-cost corridors: Computational experiments on path-based and wide-path-based models for conservation corridor design and effective distance estimation2018Inngår i: Ecological Informatics, ISSN 1574-9541, E-ISSN 1878-0512, Vol. 44, s. 109-116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Conservation of wildlife corridors has been an option to counter the problem of loss and fragmentation of wildlife habitat. A mathematical model often adopted in this option uses an algorithm for finding least-cost paths over a cost surface represented in raster format, i.e., as a grid of weighted cells. This model is easy to implement and computationally efficient, but not without drawbacks. The most notable one is that a path is a string of cells and may not be an appropriate representation of an actual wildlife corridor, which is often significantly wider than a single cell. Through computational experiments with artificial landscapes, this paper compares the existing model and an alternative model that 1) represents a corridor as a swath of cells, called a “wide path,” swept by a preset form, 2) defines the cost of a wide path as the sum of the cost-weighted areas of all its cells, and 3) finds a least-cost wide path with a selected width between two terminuses over a raster cost surface. Results suggest that the wide-path-based model is an improvement over the path-based model in that both take the same raster cost surface as input but the former finds a better corridor in terms of form and cost without sacrificing the ease of implementation and computational efficiency that the latter has. This implies that the wide-path-based model will immediately benefit ecologists and planners who use geographic information systems for the design of wildlife corridors or the study of landscape connectivity. 

  • 127.
    Shirabe, Takeshi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Drawing with geography2015Inngår i: Lecture Notes in Geoinformation and Cartography, 2015, s. 327-341Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A method is proposed to assist spatial planners in drawing with ‘geographic’ constraints. These constraints constrain graphic objects to have certain relationships that are not limited to be (Euclidean) geometric or topological but allowed to be dependent on the spatial variation of selected conditions (e.g., elevation and vegetation) characterizing an underlying geographic space. Just as in existing computer-aided design systems, the method accepts a manual change to a graphic object or constraint, and updates all affected graphic objects accordingly. The paper discusses how such a method is motivated and improves the graphic editing capability of geographic information systems, and identifies key issues for its implementation.

  • 128.
    Shirabe, Takeshi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    On distortion of raster-based least-cost corridors2016Inngår i: 9th International Conference on Geographic Information Science, GIScience 2016, Springer, 2016, s. 101-113Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Given a grid of cells each having a cost value, a variant of the least-cost path problem seeks a corridor—represented by a swath of cells rather than a sequence of cells—connecting two terminuses such that its total accumulated cost is minimized. While it is widely known that raster-based least-cost paths are subject to three types of distortion, i.e., deviation, distortion, and proximity, little is known about potential distortion of their corridor counterparts. This paper studies a raster model of the least-cost corridor problem and analyses its solution in terms of each type of distortion. It is found that raster-based least-cost corridors, too, are subject to all three types of distortion but in different ways: elongation distortion is always persistent, deviation distortion can be substantially reduced, and proximity distortion can be essentially eliminated.

  • 129.
    Skoutaris, Christoforos
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Modeling Election Results as a Function of Geodemographical and Lifestyle Variables2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 130.
    Steinvall, Felicia
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Implementation av Svensk geoprocess i kommunal verksamhet2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    I Sverige finns idag (2016) inget gemensamt standardiserat sätt för att insamla, benämna eller lagra geodata, Regeringen bestämde därför hösten 2013 att en svensk standard för geodata skulle börja att införas. Arbetet med Svensk geoprocess påbörjades samma år. Projektet med att ta fram en Svensk geodatastandard har nu pågått i tre år och till halvårsskiftet 2016 avslutas projektet

    Svensk geoprocess för att övergå i implementation av standarden. Svensk geoprocess drivs som ett samverkansprojekt mellan Sveriges Kommuner och Landsting (SKL), Lantmäteriet och Sveriges Kommuner. Rapporten syftar till att undersöka vilka avgörande faktorer som kan ha inverkan vid implementation av en nationell infrastruktur för geodata i kommunal verksamhet. För att undersöka området genomförs rapportarbetet med en trestegsmetod där varje steg bygger på föregående. I det första steget genomförs en omvärldsanalys där arbetet med en nationell infrastruktur för geodata studeras i de nordiska länderna. Rapporten behandlar även det gemensamma EU-arbetet som har genomförts inom området. I det andra steget baserat på den framkomna informationen genomfördes ett enkätutskick till alla Sveriges kommuner med frågor kring arbetet med Svensk geoprocess. I det sista steget baserat på genomförd enkät, har en intervjuer med sex utvalda personer genomförts för att förfina och utvidga svaren från enkäten.

    Dessa tre steg har slutligen gemensamt mynnat ut i de viktigaste faktorerna för en implementering av Svensk geoprocess. Dessa sex faktorer är: Kommunikation, Huvudaktörer (i detta fall kommuner, systemleverantörer och Lantmäteriet), Förvaltning, Tid, Ekonomi och Personal. Resultatet kan komma till nytta för projektet Svensk geoprocess och alla verksamheter som kommer att behöva ta beslut i frågan om implementering av Svensk geoprocess.

  • 131.
    Stromann, Oliver
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Feature Extraction and FeatureSelection for Object-based LandCover Classification: Optimisation of Support Vector Machines in aCloud Computing Environment2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Mapping the Earth’s surface and its rapid changes with remotely sensed data is a crucial tool to un-derstand the impact of an increasingly urban world population on the environment. However, the impressive amount of freely available Copernicus data is only marginally exploited in common clas-sifications. One of the reasons is that measuring the properties of training samples, the so-called ‘fea-tures’, is costly and tedious. Furthermore, handling large feature sets is not easy in most image clas-sification software. This often leads to the manual choice of few, allegedly promising features. In this Master’s thesis degree project, I use the computational power of Google Earth Engine and Google Cloud Platform to generate an oversized feature set in which I explore feature importance and analyse the influence of dimensionality reduction methods. I use Support Vector Machines (SVMs) for object-based classification of satellite images - a commonly used method. A large feature set is evaluated to find the most relevant features to discriminate the classes and thereby contribute most to high clas-sification accuracy. In doing so, one can bypass the sensitive knowledge-based but sometimes arbi-trary selection of input features.Two kinds of dimensionality reduction methods are investigated. The feature extraction methods, Linear Discriminant Analysis (LDA) and Independent Component Analysis (ICA), which transform the original feature space into a projected space of lower dimensionality. And the filter-based feature selection methods, chi-squared test, mutual information and Fisher-criterion, which rank and filter the features according to a chosen statistic. I compare these methods against the default SVM in terms of classification accuracy and computational performance. The classification accuracy is measured in overall accuracy, prediction stability, inter-rater agreement and the sensitivity to training set sizes. The computational performance is measured in the decrease in training and prediction times and the compression factor of the input data. I conclude on the best performing classifier with the most effec-tive feature set based on this analysis.In a case study of mapping urban land cover in Stockholm, Sweden, based on multitemporal stacks of Sentinel-1 and Sentinel-2 imagery, I demonstrate the integration of Google Earth Engine and Google Cloud Platform for an optimised supervised land cover classification. I use dimensionality reduction methods provided in the open source scikit-learn library and show how they can improve classification accuracy and reduce the data load. At the same time, this project gives an indication of how the exploitation of big earth observation data can be approached in a cloud computing environ-ment.The preliminary results highlighted the effectiveness and necessity of dimensionality reduction methods but also strengthened the need for inter-comparable object-based land cover classification benchmarks to fully assess the quality of the derived products. To facilitate this need and encourage further research, I plan to publish the datasets (i.e. imagery, training and test data) and provide access to the developed Google Earth Engine and Python scripts as Free and Open Source Software (FOSS).

  • 132.
    Sun, Jing
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Vu, T. T.
    Distributed and hierarchical object-based image analysis for damage assessment: a case study of 2008 Wenchuan earthquake, China2016Inngår i: Geomatics, Natural Hazards and Risk, ISSN 1947-5705, E-ISSN 1947-5713, s. 1-11Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Object-based image analysis (OBIA) is an emerging technique for analyzing remote sensing image based on object properties including spectral, geometry, contextual and texture information. To reduce the computational cost of this comprehensive OBIA and make it more feasible in disaster responses, we developed a unique approach – distributed and hierarchical OBIA approach for damage assessment. This study demonstrated a completed classification of YingXiu town, heavily devastated by the 2008 Wenchuan earthquake using Quickbrid imagery. Two distinctive areas, mountainous areas and urban, were analyzed separately. This approach does not require substantial processing power and large amounts of available memory because image of a large disaster-affected area was split in smaller pieces. Two or more computers could be used in parallel to process and analyze these sub-images based on different requirements. The approach can be applicable in other cases whereas the established set of rules can be adopted in similar study areas. More experiments will be carried out in future studies to prove its feasibility.

  • 133. Trouve, Emmanuel
    et al.
    Mercier, Gregoire
    Fauvel, Mathieu
    Bruzonne, Lorenzo
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Foreword to the Special Issue on Analysis of Multitemporal Data and Applications2016Inngår i: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 9, nr 8, s. 3356-3358Artikkel i tidsskrift (Annet vitenskapelig)
  • 134.
    Tsalikis, Nikolaos
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Analysis of dissemination of waterborne pathogens from raw water and related health issues in Sweden using GIS2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Water-related diseases are a major issue of public health worldwide. Raw drinking water retrieved from surface and groundwater undergoes treatment at water treatment plants in order to disable certain microorganisms that if were to be released in drinking water, would cause a variety of unwanted gastrointestinal symptoms. As such, it is imperative that research goes in the direction of preventing the entry of such microorganisms in drinking water by identifying potential risk situations involving high concentrations in raw water.

     

    The objective of this thesis research is to examine variations and peaks in concentrations of notable pathogens found in raw water samples retrieved from the influx of five different water treatment facilities in Sweden, along with visualisations of related health symptoms that might have been the result of pathogen contamination in areas that were supplied by those waterworks. The primary source for the raw water data is Folkhälsomyndigheten (Public Health Agency of Sweden) and covers the period of March 2014 to 2015 in an ongoing project, however data from before this project started have also been retrieved from Vattentäktsarkivet covering the period of 2009-2013 for the representative waterworks. The data used to visualise the related health symptoms were retrieved from Healthcare Guide 1177, based on telephone triage. Along with that data, SCB data on population were used along with a shapefile of postal areas of Sweden, provided by Postnummerservice.

     

    In order to visualise symptoms across time and to examine possible rises of symptoms related to gastrointestinal diseases across the period of analysis, Excel and Geographical Information System (GIS) toolboxes Spatial Analyst and Data Management were used in order to process the data from 1177, create time-animated outputs that depicted the symptoms monthly for every area and to identify areas that reported the most symptoms using density maps and hot-spot analysis. Statistical analysis and graphs for the data regarding the raw water dataset were performed in Excel.

     

    The results implied minor correlations between high concentrations of notable pathogens in raw water and a rise of symptoms reported to 1177 in some months and areas during the period of analysis. The suspect months and areas were identified through a visualisation of clusters of symptoms and increases in comparison to normal seasonal effects. The winter months along with March and April generally showed the highest number of reported symptoms in all counties and a comparison of incidence rates revealed that the municipalities of Östersund and Trollhättan had the highest incidence rates in regards to their population.

     

    A large source of error in the analysis is the raw water dataset itself. Since raw water always undergoes treatment, it is typically assumed that pathogens are removed prior to entering drinking water. It is possible that pathogens might elude this process, though it is difficult to exclude other sources of infection, such as contaminated food or seasonal contagious effects like winter-vomiting disease without access to patient records.

  • 135.
    Uggla, Gustaf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    3D City Models - A Comparative Study of Methods and Datasets2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    There are today many available datasets and methods that can be used to create 3D city models, which in turn can be used for numerous applications within the fields of visualization, communication and analysis. The purpose of this thesis is to perform a practical comparison between three methods for 3D city modeling using different combinations of datasets; one using LiDAR data combined with oriented aerial images, one using only oriented aerial images and one using non-oriented aerial images. In all three cases, geometry and textures are derived from the data and the models are imported into the game engine Unity. The three methods are evaluated in terms of the resulting model, the amount of manual work required and the time consumed as well as the cost of data and software licenses. An application example visualizing flooding scenarios in central Stockholm is featured in the thesis to give a simple demonstration of what can be done with 3D city models in a game engine environment. The result of the study shows that combining LiDAR data with oriented images and using a more manual process to create the model gives a higher potential for the result, both in terms of visual appearance and semantic depth. Using only oriented images and commercial software is the easiest and most reliable way to create a usable 3D city model. Non-oriented images and open-source software can be used for 3D reconstruction but is not suited for larger areas or geographic applications. Finding reliable automatic or semi-automatic methods to create semantically rich 3D city models from remote sensed data would be hugely beneficial, as more sophisticated applications could be programmed with the 3D city model as a base.

  • 136.
    Wang, Wei
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. National University of Defense Technology, China.
    Spatially Adaptive Analysis and Segmentation of Polarimetric SAR Data2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In recent years, Polarimetric Synthetic Aperture Radar (PolSAR) has been one of the most important instruments for earth observation, and is increasingly used in various remote sensing applications. Statistical modelling and scattering analysis are two main ways for PolSAR data interpretation, and have been intensively investigated in the past two decades. Moreover, spatial analysis was applied in the analysis of PolSAR data and found to be beneficial to achieve more accurate interpretation results. This thesis focuses on extracting typical spatial information, i.e., edges and regions by exploring the statistical characteristics of PolSAR data. The existing spatial analysing methods are mainly based on the complex Wishart distribution, which well characterizes the inherent statistical features in homogeneous areas. However, the non-Gaussian models can give better representation of the PolSAR statistics, and therefore have the potential to improve the performance of spatial analysis, especially in heterogeneous areas. In addition, the traditional fixed-shape windows cannot accurately estimate the distribution parameter in some complicated areas, leading to the loss of the refined spatial details. Furthermore, many of the existing methods are not spatially adaptive so that the obtained results are promising in some areas whereas unsatisfactory in other areas. Therefore, this thesis is dedicated to extracting spatial information by applying the non-Gaussian statistical models and spatially adaptive strategies. The specific objectives of the thesis include: (1) to develop reliable edge detection method, (2) to develop spatially adaptive superpixel generation method, and (3) to investigate a new framework of region-based segmentation. Automatic edge detection plays a fundamental role in spatial analysis, whereas the performance of classical PolSAR edge detection methods is limited by the fixed-shape windows. Paper 1 investigates an enhanced edge detection method using the proposed directional span-driven adaptive (DSDA) window. The DSDA window has variable sizes and flexible shapes, and can overcome the limitation of fixed-shape windows by adaptively selecting homogeneous samples. The spherically invariant random vector (SIRV) product model is adopted to characterize the PolSAR data, and a span ratio is combined with the SIRV distance to highlight the dissimilarity measure. The experimental results demonstrated that the proposed method can detect not only the obvious edges, but also the tiny and inconspicuous edges in heterogeneous areas. Edge detection and region segmentation are two important aspects of spatial analysis. As to the region segmentation, paper 2 presents an adaptive PolSAR superpixel generation method based on the simple linear iterative clustering (SLIC) framework. In the k-means clustering procedure, multiple cues including polarimetric, spatial, and texture information are considered to measure the distance. Since the constant weighting factor which balances the spectral similarity and spatial proximity may cause over- or under-superpixel segmentation in different areas, the proposed method sets the factor adaptively based on the homogeneity analysis. Then, in heterogeneous areas, the spectral similarity is more significant than the spatial constraint, generating superpixels which better preserved local details and refined structures. Paper 3 investigates another PolSAR superpixel generation method, which is achieved from the global optimization aspect, using the entropy rate method. The distance between neighbouring pixels is calculated based on their corresponding DSDA regions. In addition, the SIRV distance and the Wishart distance are combined together. Therefore, the proposed method makes good use of the entropy rate framework, and also incorporates the merits of the SIRV distance and the Wishart distance. The superpixels are generated in a homogeneity-adaptive manner, resulting in smooth representation of the land covers in homogeneous areas, and well preserved details in heterogeneous areas.

  • 137.
    Wang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Xiang, D.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Zhang, J.
    Wan, J.
    Superpixel-based segmentation of polarimetric SAR images through two-stage merging2019Inngår i: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 11, nr 4, artikkel-id 402Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Image segmentation plays a fundamental role in image understanding and region-based applications. This paper presents a superpixel-based segmentation method for Polarimetric SAR (PolSAR) data, in which a two-stage merging strategy is proposed. First, based on the initial superpixel partition, the Wishart-merging stage (WMS) simultaneously merges the regions in homogeneous areas. The edge penalty is combined with the Wishart energy loss to ensure that the superpixels to be merged are from the same land cover. The second stage follows the iterative merging procedure, and applies the doubly flexible KummerU distribution to better characterize the resultant regions from WMS, which are usually located in heterogeneous areas. Moreover, the edge penalty and the proposed homogeneity penalty are adopted in the KummerU-merging stage (KUMS) to further improve the segmentation accuracy. The two-stage merging strategy applies the general statistical model for the superpixels without ambiguity, and more advanced model for the regions with ambiguity. Therefore, the implementing efficiency can be improved based on the WMS, and the accuracy can be increased through the KUMS. Experimental results on two real PolSAR datasets show that the proposed method can effectively improve the computation efficiency and segmentation accuracy compared with the classical merging-based methods.

  • 138.
    Wang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Xiang, Deliang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Zhang, Jun
    Natl Univ Def Technol, Coll Elect Sci & Engn, Changsha, Hunan, Peoples R China..
    Wan, Jianwei
    Natl Univ Def Technol, Coll Elect Sci & Engn, Changsha, Hunan, Peoples R China..
    Enhanced edge detection for polarimetric SAR images using a directional span-driven adaptive window2018Inngår i: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, Vol. 39, nr 19, s. 6340-6357Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Automatic edge detection for polarimetric synthetic aperture radar (PolSAR) images plays a fundamental role in various PolSAR applications. The classic methods apply the fixed-shape windows to detect the edges, whereas their performance is limited in heterogeneous areas. This article presents an enhanced edge detection method for PolSAR data based on the directional span-driven adaptive (DSDA) window. The DSDA window has variable sizes and flexible shapes, and is constructed by adaptively selecting samples that follow the same statistical distribution. Therefore, it can overcome the limitation of classic fixed-shape windows. To obtain refined and reliable edge detection results in heterogeneous urban areas, we adopt the spherically invariant random vector (SIRV) product model since the complex Wishart distribution is often not met. In addition, a span ratio is combined with the SIRV distance to highlight the dissimilarity measure and to improve the robustness of the proposed method. The simulated PolSAR data and three real data sets from experimental synthetic aperture radar, electromagnetics institute synthetic aperture radar, and Radarsat-2 systems are used to validate the performance of the enhanced edge detector. Both quantitative evaluation and visual presentation of the results demonstrate the effectiveness of the proposed method and its superiority over the classic edge detectors.

  • 139.
    Wang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. National University of Defense Technology.
    Xiang, Deliang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Zhang, Jun
    Wan, Jianwei
    Enhanced Edge Detection for Polarimetric SAR Images Using Directional Span-Driven Adaptive WindowManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Automatic edge detection for polarimetric synthetic aperture radar (PolSAR) images plays a fundamental role in various PolSAR applications. The classic methods apply the fixed-shape windows to detect the edges, whereas their performance is limited in heterogeneous areas. This paper presents an enhanced edge detection method for PolSAR data based on the directional span-driven adaptive (DSDA) window. The DSDA window has variable sizes and flexible shapes, and is constructed by adaptively selecting samples which follow the same statistical distribution. Therefore, it can overcome the limitation of classic fixed-shape windows. To obtain refined and reliable edge detection results in heterogeneous urban areas, we adopt the spherically invariant random vector (SIRV) product model, since the complex Wishart distribution is often not met. In addition, a span ratio is combined with the SIRV distance to highlight the dissimilarity measure and to improve the robustness of the proposed method. The simulated PolSAR data and three real data sets from ESAR, EMISAR and RADARSAT-2 systems are used to validate the performance of the enhanced edge detector. Both quantitative evaluation and visual presentation of the results demonstrate the effectiveness of the proposed method and its superiority over the classic edge detectors.

  • 140.
    Wang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. National University of Defense Technology.
    Xiang, Deliang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Zhang, Jun
    Wan, Jianwei
    Superpixel Segmentation of Polarimetric SAR Data Based on Integrated Distance Measure and Entropy Rate Method2017Inngår i: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 10, nr 9, s. 4045-4058Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper proposes to integrate two different distances to measure the dissimilarity between neighboring pixels in PolSAR images, and introduces the entropy rate method into PolSAR image superpixel segmentation. Since the Gaussian model is commonly used for homogeneous scenes and less suitable for heterogeneous scenes, we adopt the spherically invariant random vector (SIRV) model to describe the back-scattering characteristics in heterogeneous areas. Moreover, a directional span-driven adaptive (DSDA) region is proposed such that it contains independent and identically distributed samples only, thus it can obtain accurate estimation of the distribution parameters. Using the DSDA region, the Wishart distance and SIRV distance are calculated, and then combined together through a homogeneity measurement. Therefore, the integrated distance takes advantage of the SIRV model and the Gaussian model, and suits both homogeneous and heterogeneous areas. Finally, based on the integrated distance, the superpixel segments are generated using the entropy rate framework. The experimental results on ESAR and PiSAR L-band datasets show that the proposed method can generate homogeneity-adaptive segments, resulting in smooth representation of the land covers in homogeneous areas, and better preserved details in heterogeneous areas.

  • 141.
    Wang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. National University of Defense Technology, China.
    Xiang, Deliang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Zhang, Jun
    Wan, Jianwei
    Superpixel-Based Segmentation of Polarimetric SAR Images through Two-Stage MergingManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    This paper presents a superpixel-based segmentation method for multilook polarimetric SAR (PolSAR) data. By exploring the PolSAR statistics, a two-stage merging strategy is proposed to improve the segmentation efficiency and accuracy. First, based on the initial superpixel partition, the Wishart-merging stage (WMS) simultaneously merges the regions in homogeneous areas, which can be modelled by the Wishart distribution. The Wishart energy loss together with the edge penalty is utilized so that the merged superpixels are from the same land cover and without ambiguity. In the second stage, the doubly flexible two-parameter KummerU distribution is applied to better characterize the resultant regions from the WMS, which are usually located in heterogeneous areas. This KummerU-merging stage (KUMS) iteratively merges the adjacent regions based on the KummerU energy loss. In addition, the edge penalty and the proposed homogeneity penalty are also adopted to guide the merging procedure, and prevent merging the regions from distinct land covers. Compared with the classical iterative merging methods, the two-stage merging strategy can improve the efficiency based on the WMS, and increase the segmentation accuracy through the KUMS. Two experimental PolSAR datasets acquired by ESAR and EMISAR system are used to demonstrate the effectiveness of the proposed segmentation method.

  • 142.
    Wang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. Natl Univ Def Technol, Peoples R China.
    Xiang, Deliang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Zhang, Jun
    Wan, Jianwei
    Integrating Contextual Information With H/(alpha)over-bar Decomposition for PolSAR Data Classification2016Inngår i: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 13, nr 12, s. 2034-2038Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of contextual information is beneficial to improve both the accuracy and reliability of image classification. Based on the robust fuzzy c-means (RFCM) clustering method and an adaptive Markov random field model, this letter proposes a contextual H/(alpha) over bar classifier for polarimetric synthetic aperture radar images. At each iterative step of RFCM clustering, the prior probability extracted from the local neighborhood is combined with the fuzzy membership derived from inherent polarimetric characteristics, thus the enhanced fuzzy membership is more reliable. In addition, an adaptive smoothing factor is proposed for use during contextual information retrieval, which can prevent oversmoothing and preserve the local spatial details. The experimental results implemented using AIRSAR and ESAR L-band data validate the efficacy of the proposed method. Compared with the iterated Wishart classifier and fuzzy H/(alpha) over bar classifier, the proposed method significantly improves the classification accuracy, with less noise and increased preservation of details.

  • 143.
    Wang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Yang, Lili
    Wang, Nan
    Zhang, Haifeng
    Jia, Yanping
    Design of a Thermoelectric Material Using the CALPHAD Technique: Thermodynamic Reassessment of the Al-Sb-Zn System2018Inngår i: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 47, nr 1, s. 261-271Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The beta-Sb3Zn4 intermetallic compound, one of the most promising thermoelectric materials in the mid-1990s, has attracted much interest due to its high thermoelectric performance in the intermediate temperature range. To improve the thermoelectric properties of the compound beta-Sb3Zn4, Al doping is an effective method. Therefore, accurate theoretical analysis of the Al-Sb-Zn system is essential for the design of such thermoelectric materials. In this work, the Al-Sb-Zn system was reassessed by means of the calculation of phase diagram (CALPHAD) technique. A set of self-consistent thermodynamic parameters was obtained and can be used to extrapolate to related high-order systems. Some phase equilibria and thermochemical properties can be predicted using the present thermodynamic description.

  • 144.
    Wang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Zhai, Qinglin
    Natl Univ Def Technol, Coll Elect Sci & Engn, Changsha 410073, Hunan, Peoples R China..
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Zhang, Jun
    Natl Univ Def Technol, Coll Elect Sci & Engn, Changsha 410073, Hunan, Peoples R China..
    Wan, Jianwei
    Natl Univ Def Technol, Coll Elect Sci & Engn, Changsha 410073, Hunan, Peoples R China..
    POLSAR IMAGE SEGMENTATION BASED ON HIERARCHICAL REGION MERGING AND SEGMENT REFINEMENT WITH WMRF MODEL2017Inngår i: 2017 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS), IEEE , 2017, s. 4574-4577Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, a superpixel-based segmentation method is proposed for PolSAR images by utilizing hierarchical region merging and segment refinement. The loss of the energy function, which determines the consistency of two adjacent regions from the statistical aspect, is applied to guide the merging procedure. In addition to the edge penalty term, the homogeneity measurement is also employed to prevent merging the regions that are from different land covers or objects. Based on the merged segments, the segment refinement is applied to further improve the segmentation accuracy by iteratively relabeling the edge pixels. It uses a maximum a posterior (MAP) criterion using the statistical distribution of the pixels and the Markov random field (MRF) model. The performance of the proposed method is validated on an experimental PolSAR dataset from the ESAR system.

  • 145. Weng, Qihao
    et al.
    Gamba, Paolo
    Mountrakis, G.
    Pesaresi, M.
    Lu, L.
    Kemper, T.
    Heinzel, J.
    Xian, G.
    Jin, H
    Miyazaki, H.
    Xu, B.
    Quresh, S.
    Keramitsoglou, I.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Esch, T.
    Roth, A,
    Elvidge, C. D.
    Chapter 4. Urban Observing Sensors2014Inngår i: Global Urban Monitoring and Assessment through Earth Observation / [ed] Qihao Weng, CRC Press, 2014, s. 49-80Kapittel i bok, del av antologi (Fagfellevurdert)
  • 146.
    Wu, Feng
    et al.
    Chinese Acad Sci, Ctr Chinese Agr Policy, Inst Geog Sci & Nat Resources Res, Beijing 100101, Peoples R China.;Univ Chinese Acad Sci, Beijing 100049, Peoples R China..
    Sun, Yufan
    Univ Hong Kong, Fac Engn, Pokfulam, Hong Kong, Peoples R China..
    Sun, Zhongxiao
    Leiden Univ, Inst Environm Sci CML, NL-2300 RA Leiden, Netherlands..
    Wu, Sihong
    Natl Ctr Sci & Technol Evaluat, Beijing 100081, Peoples R China..
    Zhang, Qian
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. Chinese Acad Sci, Ctr Chinese Agr Policy, Inst Geog Sci & Nat Resources Res, Beijing 100101, Peoples R China.;Univ Chinese Acad Sci, Beijing 100049, Peoples R China.;Hebei Univ, Collaborat Innovat Ctr Baiyangdian Basin Ecol Pro, Baoding 071002, Peoples R China..
    Assessing agricultural system vulnerability to floods: A hybrid approach using emergy and a landscape fragmentation index2019Inngår i: Ecological Indicators, ISSN 1470-160X, E-ISSN 1872-7034, Vol. 105, s. 337-346Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In recent decades, the frequencies and intensities of extreme weather events have increased in many parts of the world. Floods, as one of the main types of extreme weather event, have a major influence on agroecosystem productivity, and, in turn, on agricultural income and food security. Consequently, analyzing agricultural system vulnerability to floods plays a significant role in food production and agroecosystem health. In this study, we establish a three-layer indicator system to evaluate agricultural vulnerability at the county level for flood-prone regions in China. Specifically, in the first layer, we assess agricultural vulnerability to floods based on the constructs of exposure, sensitivity, and adaptability. Indicators in the second layer include precipitation, runoff, land use, and capital, and are measured to capture the primary constructs. Together, the indicators are used to calculate agricultural system vulnerability to floods. We then innovatively correct the assessment results of vulnerability with the aid of a landscape fragmentation index, given that landscape fragmentation is known to influence the vulnerability of agricultural systems. The results for agricultural vulnerability to floods demonstrate clear spatial variations at the county level in 1995, 2000, 2005, and 2010, and also show changes in the spatial distribution of vulnerability over time. In this regard, areas that are distributed near inland rivers, lakes, and the southern coastal areas, and those areas with dense river networks, have relatively high vulnerabilities. The assessment results also indicate that the maximum and average intensities of vulnerability have decreased over time, although the extent of vulnerable agricultural land has increased. Importantly, by comparing the results between selected county pairs, the assessment results corrected using landscape fragmentation index is verified to be more robust and objective than without correction.

  • 147. Wu, Feng
    et al.
    Sun, Zhongxiao
    Wang, Fengting
    Zhang, Qian
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. University of the Chinese Academy of Sciences, China.
    Identification of the critical transmission sectors and typology of industrial water use for supply-chain water pressure mitigation2018Inngår i: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 131, s. 305-312Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The industrial system produces pressure on water resources by directly consuming the water needed for industrial production and by indirectly consuming water through intermediate inputs. To date, identifying the critical transmission sectors for supply-chain water resources pressure mitigation has been under-examined. To fill this gap in knowledge, we use a betweenness-based method in combination with the standard input output table extended with water-resource sector accounts to identify the key transmission sectors using Zhangye City in the Heihe River Basin, China as an example. The results show that the sectors with low rankings of the production-based indicator do not consume large amounts of water resources to directly generate products, which demonstrates that these sectors have limited scope for reducing water-resource consumption. The results also indicate that those sectors having higher betweenness-based water use but lower consumption-based and production-based water use merit close attention because these sectors transmit relatively large amounts of water resources embodied in their intermediate inputs from water-intensive upstream industrial sectors. Consequently, improving production efficiency in these sectors has an indirect effect by lowering the consumption of upstream water resources. This study also shows that the betweenness-based indicator is able to provide additional information beyond that given by the usual metrics derived from the production and demand sides. Moreover, the typology of water use that we innovatively generate is able to inform corresponding and targeted sector-specific policies and strategies for mitigating water resources pressure.

  • 148.
    Xiang, Deliang
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. National University of Defense Technology, China.
    Ban, Yifang
    Su, Yi
    The cross-scattering component of polarimetric SAR in urban areas and its application to model-based scattering decomposition2016Inngår i: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, Vol. 37, nr 16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    After the work of Freeman, Durden, Pottier, and Yamaguchi, manydecomposition techniques have been proposed for urban areas, mainly to resolvethe overestimation problem of volume scattering. Since it has been validated thatthe cross-polarised (HV) scattering is caused not only by forests but also byrotated dihedrals, in this paper, we propose a cross scattering coherency matrix tomodel the HV component from orientated and complex buildings and thendemonstrate its performance on model-based scattering decomposition. Thebuilding orientation angle is considered in this coherency matrix, making itflexible and adaptive in the decomposition. Therefore, the HV components fromforests and orientated urban areas can be modelled respectively. Twodecomposition procedures are applied in this paper. The first one is to validatethe effectiveness of this scattering model. We regard the HV component fromurban areas as cross scattering, which is an independent scattering componentadded to the Yamaguchi four-component decomposition. Another one is theurban area decomposition application using this scattering model. Decompositionis implemented for urban and natural areas respectively and the HV componentfrom urban areas is regarded as their volume scattering. This procedure is similarto many other state-of-the-art methods for urban areas and needs to discriminatethe urban and natural areas before decomposition. Spaceborne Radarsat-2 C band,the Airborne Synthetic Aperture Radar (AIRSAR) L band and UninhabitedAerial Vehicle Synthetic Aperture Radar (UAVSAR) L band full polarimetricSAR data are used to validate the performance of this cross scattering coherencymatrix. The HV component of orientated buildings is generated, leading to abetter decomposition result for urban areas.

  • 149.
    Xiang, Deliang
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. National University of Defense Technology, China.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. National University of Defense Technology, China.
    Wang, Wei
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. National University of Defense Technology, China.
    Su, Yi
    Adaptive Superpixel Generation for Polarimetric SAR Images With Local Iterative Clustering and SIRV Model2017Inngår i: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, E-ISSN 1558-0644, Vol. 55, nr 6, s. 3115-3131Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Simple linear iterative clustering (SLIC) algorithm was proposed for superpixel generation on optical images and showed promising performance. Several studies have been proposed to modify SLIC to make it applicable for polarimetric synthetic aperture radar (PolSAR) images, where the Wishart distance is adopted as the similarity measure. However, the superpixel segmentation results of these methods were not satisfactory in heterogeneous urban areas. Further, it is difficult to determine the tradeoff factor which controls the relative weight between polarimetric similarity and spatial proximity. In this research, an adaptive polarimetric SLIC (Pol-ASLIC) superpixel generation method is proposed to overcome these limitations. First, the spherically invariant random vector (SIRV) product model is adopted to estimate the normalized covariance matrix and texture for each pixel. A new edge detector is then utilized to extract PolSAR image edges for the initialization of central seeds. In the local iterative clustering, multiple cues including polarimetric, texture, and spatial information are considered to define the similarity measure. Moreover, a polarimetric homogeneity measurement is used to automatically determine the tradeoff factor, which can vary from homogeneous areas to heterogeneous areas. Finally, the SLIC superpixel generation scheme is applied to the airborne Experimental SAR and PiSAR L-band PolSAR data to demonstrate the effectiveness of this proposed superpixel generation approach. This proposed algorithm produces compact superpixels which can well adhere to image boundaries in both natural and urban areas. The detail information in heterogeneous areas can be well preserved.

  • 150.
    Xiang, Deliang
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Wang, Wei
    Tang, Tao
    Su, Yi
    Edge Detector for Polarimetric SAR Images Using SIRV Model and Gauss-Shaped Filter2016Inngår i: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 13, nr 11, s. 1661-1665Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The classic constant false alarm rate edge detector with a rectangle-shaped filter has been proven to be effective and widely used in polarimetric synthetic aperture radar (PolSAR) images. However, in practical use, the assumption of complex Wishart distribution is often not respected, particularly in heterogeneous urban areas. In addition, as a simple smoothing filter, the rectangle-shaped window is often shown to be easy to incur false edge pixels near true edges. Therefore, its performance is limited. To overcome this restriction, we propose a new edge detector for PolSAR images, which utilizes the spherically invariant random vector product model to estimate the normalized covariance matrix for each pixel, and then replace the rectangle-shaped filter with a Gauss-shaped filter. The performance of our proposed methodology is presented and analyzed on two real PolSAR data sets, and the results show that the new edge detector attains better performance than the classic one, particularly for urban areas.

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