Change search
Refine search result
1 - 20 of 20
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Cao, J.
    et al.
    Liu, Y.
    Luo, J.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Efficient multi-QoS attributes negotiation for service composition in dynamically changeable environments2010In: 2010 IEEE International Conference on Systems Man and Cybernetics (SMC), 2010, p. 3118-3124Conference paper (Refereed)
    Abstract [en]

    Service composition with Quality of Service (QoS) is widely studied nowadays and there are some approaches effective for the composition problem in ideal conditions but no feasible solution for dynamic and uncertain QoS constraints environment. Therefore, a novel service negotiation mechanism is proposed in this paper. The mechanism is composed by three parts for negotiation: model, protocol and strategy. The model creates a new hierarchy architecture based on negotiation agent to improve the efficiency of tasks execution of each agent. The protocol dynamically updates solution search line, on which proposals are made by trading partners, and approximate Pareto-optimal solution is achieved through the neutral mediator. The strategy enhances the negotiation sensibility by considering three factors: time, opponent actions and global negotiation states. The negotiation process is coordinated by Manger Agent (MA), which provides suggestions for the next negotiation round based on the overall negotiation context. Experimental results show that the proposed approach is effective to find a feasible solution in the dynamically changeable composition environment.

  • 2. Cao, J.
    et al.
    Sun, X.
    Zheng, X.
    Liu, B.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Efficient multi-objective services selection algorithm based on particle swarm optimization2010In: Proceedings - 2010 IEEE Asia-Pacific Services Computing Conference, APSCC 2010, IEEE , 2010, p. 603-608Conference paper (Refereed)
    Abstract [en]

    With the development of Web Service, it has become a key issue to select appropriate services from a large number of candidates for creating complex composite services according to users' different QoS levels requirements. However, the existing service selection algorithms have many defects such as high time complexity, non-global optimal solutions, and poor quality solutions. To solve these defects, an efficient multi-objective services selection algorithm, EMOSS, is proposed in this paper based on particle swarm optimization. The essence of EMOSS is to model the service selection problem as a constrained multi-objective optimization problem. First the services in each sub-service set are sorted by their concept of domination, then the new sub-service set nSi , whose size is far less than the original one, is constructed and finally output pareto optimal set. The theoretical analysis and experimental results show that EMOSS can effectively obtain high quality solutions.

  • 3. Cao, J.
    et al.
    Wang, T.
    Shi, L.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Architecture and algorithm for web phishing detection2010In: Journal of Southeast University (English Edition), ISSN 1003-7985, Vol. 26, no 1, p. 43-47Article in journal (Refereed)
    Abstract [en]

    A phishing detection system, which comprises client-side filtering plug-in, analysis center and protected sites, is proposed. An image-based similarity detection algorithm is conceived to calculate the similarity of two web pages. The web pages are first converted into images, and then divided into sub-images with iterated dividing and shrinking. After that, the attributes of sub-images including color histograms, gray histograms and size parameters are computed to construct the attributed relational graph (ARG) of each page. In order to match two ARGs, the inner earth mover's distances (EMD) between every two nodes coming from each ARG respectively are first computed, and then the similarity of web pages by the outer EMD between two ARGs is worked out to detect phishing web pages. The experimental results show that the proposed architecture and algorithm has good robustness along with scalability, and can effectively detect phishing.

  • 4. Cao, J.
    et al.
    Yang, L.
    Zheng, X.
    Liu, B.
    Zhao, L.
    Ni, X.
    Dong, F.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Social attribute based web service information publication mechanism in delay tolerant network2011In: Proc. - IEEE Int. Conf. Comput. Sci. Eng., CSE Int. Symp. Pervasive Syst., Algorithms, Networks, I-SPAN IEEE Int. Conf. IUCC, 2011, p. 435-442Conference paper (Refereed)
    Abstract [en]

    The intermittence of the connection between nodes and limited resources greatly impair the effectiveness of service information publication in Delay Tolerant Network (DTN). To overcome this problem, a multi-layer service information cooperative publication mechanism is proposed in this paper. Firstly, the social interaction network and service overlay network is established in the form of abstract weight graph. Then, the community division algorithm is used to analysis the social characteristics of service interaction and the social attribute based DTN model-S-DTN is constructed. Finally, the carrier nodes of the information publication is selected from neighbor set by computing utilization function based node context, and a multi-layer cooperative mechanism is proposed to achieve effective service information publication in DTN. The experiment results indicate that the proposed publication mechanism brings nearly the same success ratio as Epidemic Routing with lower delay and network loads. Additionally, it shows better performance in overall metrics than Prophet Routing.

  • 5. Cao, J.
    et al.
    Zhang, B.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    Bo, L.
    Constraint rules-based recovery for business transaction2010In: Proceedings - 9th International Conference on Grid and Cloud Computing, GCC 2010, 2010, p. 282-289Conference paper (Refereed)
    Abstract [en]

    In web service computing, a business transaction is integrated by web services provided by multiple enterprises, therefore the transaction is deployed in a loose-coupled, heterogeneous and autonomous environment. When failures or exceptions occur, the traditional rolling back technique is inappropriate for recovery since locking is inapplicable. Current solutions, including forward recovery and backward recovery, didn't take into consideration enough business logic of the business transaction and thus were lack of flexibility and efficiency. In this paper, we introduce the conception-constraint rule, which express the business logic of a business transaction. A better control of recovery is achieved based on the constraint rules. A detailed description of our algorithms for recovery is given and a travel agency case study is illustrated. In addition, we compare our recovery mechanism with some existing solutions and the simulation results show that our method has both better success rate and efficiency.

  • 6.
    Fan, Hongchao
    et al.
    Department of Cartography, Technical University of Munich.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Meng, Liqiu
    Department of Cartography, Technical University of Munich.
    An automatic approach for the typification of façade structuresIn: ISPRS journal of photogrammetry and remote sensing (Print), ISSN 0924-2716, E-ISSN 1872-8235Article in journal (Other academic)
    Abstract [en]

    Typification is a well-established operator of map generalization. Although it is widely used in many existing research fields, less discussion has been devoted to the quality of typification. This paper presents a user survey for the evaluation of different typification results of façade structures under different constraints. The survey shows that preservation of the shape of the features is the most important constraint for a reasonable typification process, which has also been quantitatively verified by calculating the similarities between the typified façades and the original façade using attributed relational graph (ARG) and nested earth mover’s distance (NEMD) algorithms. Based on that, an algorithm is developed to generate perceivably reasonable representation from the original facade with decreasing map scale. The algorithm is implemented and tested on a number of façades. Experiments reveal that the typification can be automatically conducted and can create results which are well associated with the original façades.

  • 7.
    Fan, Hongchao
    et al.
    Department of Cartography, Technical University of Munich.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Shen, Jie
    Nanjing Normal University.
    Meng, Liqiu
    Department of Cartography, Technical University of Munich.
    Shell model representation as a substitute of LOD3 for 3D modeling in CityGML2011In: Geo-spatial Information Science, ISSN 1009-5020, Vol. 14, no 2, p. 78-84Article in journal (Refereed)
    Abstract [en]

    The OGC standard for 3D city modeling is widely used in an increasing number of applications. It defines five consecutive Levels of Detail (LoD0 to LoD4 with increasing accuracy and structural complexity), in which LoD3 includes all exterior appearances and geometrical details and subsequently requires much storage space. A new LoD is introduced as shell model with the exterior shell of the LoD3 model and the opening objects like windows, doors as well as smaller façade objects are projected onto walls. In this paper, a user survey is presented. The results of this survey show that the shell model can give users almost the same visual impression as the LoD3 model. Furthermroe, algorithms are developed to extract the shell model from LoD3 model. Experiments show that this shell model can reduce up to 90% storage of the original LoD3 model. Therefore, on one hand it can be used as a substitute for a LoD3 model for the visualization on small displays. On the other hand, it can be treated as a sub-level of detail (SLoD3) in CityGML, since it retains almost the same amount of information but requires much less storage space.

  • 8.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Visualisation and Generalisation of 3D City Models2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    3D city models have been widely used in various applications such as urban planning, traffic control, disaster management etc. Efficient visualisation of 3D city models in different levels of detail (LODs) is one of the pivotal technologies to support these applications. In this thesis, a framework is proposed to visualise the 3D city models online. Then, generalisation methods are studied and tailored to create 3D city scenes in different scales dynamically. Multiple representation structures are designed to preserve the generalisation results on different level. Finally, the quality of the generalised 3D city models is evaluated by measuring the visual similarity with the original models.

     

    In the proposed online visualisation framework, City Geography Makeup Language (CityGML) is used to represent city models, then 3D scenes in Extensible 3D (X3D) are generated from the CityGML data and dynamically updated to the user side for visualisation in the Web-based Graphics Library (WebGL) supported browsers with X3D Document Object Model (X3DOM) technique. The proposed framework can be implemented at the mainstream browsers without specific plugins, but it can only support online 3D city model visualisation in small area. For visualisation of large data volumes, generalisation methods and multiple representation structures are required.

     

    To reduce the 3D data volume, various generalisation methods are investigated to increase the visualisation efficiency. On the city block level, the aggregation and typification methods are improved to simplify the 3D city models. On the street level, buildings are selected according to their visual importance and the results are stored in the indexes for dynamic visualisation. On the building level, a new LOD, shell model, is introduced. It is the exterior shell of LOD3 model, in which the objects such as windows, doors and smaller facilities are projected onto walls.  On the facade level, especially for textured 3D buildings, image processing and analysis methods are employed to compress the texture.

     

    After the generalisation processes on different levels, multiple representation data structures are required to store the generalised models for dynamic visualisation. On the city block level the CityTree, a novel structure to represent group of buildings, is tested for building aggregation. According to the results, the generalised 3D city model creation time is reduced by more than 50% by using the CityTree. Meanwhile, a Minimum Spanning Tree (MST) is employed to detect the linear building group structures in the city models and they are typified with different strategies. On the building level and the street level, the visible building index is created along the road to support building selection. On facade level the TextureTree, a structure to represent building facade texture, is created based on the texture segmentation.

     

    Different generalisation strategies lead to different outcomes. It is critical to evaluate the quality of the generalised models. Visually salient features of the textured building models such as size, colour, height, etc. are employed to calculate the visual difference between the original and the generalised models. Visual similarity is the criterion in the street view level building selection. In this thesis, the visual similarity is evaluated locally and globally. On the local level, the projection area and the colour difference between the original and the generalised models are considered. On the global level, the visual features of the 3D city models are represented by Attributed Relation Graphs (ARG) and their similarity distances are calculated with the Nested Earth Mover’s Distance (NEMD) algorithm.

     

    The overall contribution of this thesis is that 3D city models are generalised in different scales (block, street, building and facade) and the results are stored in multiple representation structures for efficient dynamic visualisation, especially for online visualisation.

  • 9.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Visualisation and Generalisation of 3D City Models2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    3D city models have been widely used in different applications such as urban planning, traffic control, disaster management etc. Effective visualisation of 3D city models in various scales is one of the pivotal techniques to implement these applications. In this thesis, a framework is proposed to visualise the 3D city models both online and offline using City Geography Makeup Language (CityGML) and Extensible 3D (X3D) to represent and present the models. Then, generalisation methods are studied and tailored to create 3D city scenes in multi-scale dynamically. Finally, the quality of generalised 3D city models is evaluated by measuring the visual similarity from the original models.

     

    In the proposed visualisation framework, 3D city models are stored in CityGML format which supports both geometric and semantic information. These CityGML files are parsed to create 3D scenes and be visualised with existing 3D standard. Because the input and output in the framework are all standardised, it is possible to integrate city models from different sources and visualise them through the different viewers.

     

    Considering the complexity of the city objects, generalisation methods are studied to simplify the city models and increase the visualisation efficiency. In this thesis, the aggregation and typification methods are improved to simplify the 3D city models.

     

    Multiple representation data structures are required to store the generalisation information for dynamic visualisation. One of these is the CityTree, a novel structure to represent building group, which is tested for building aggregation. Meanwhile, Minimum Spanning Tree (MST) is employed to detect the linear building group structures in the city models and they are typified with different strategies. According to the experiments results, by using the CityTree, the generalised 3D city model creation time is reduced by more than 50%.

     

    Different generalisation strategies lead to different outcomes. It is important to evaluate the quality of the generalised models. In this thesis a new evaluation method is proposed: visual features of the 3D city models are represented by Attributed Relation Graph (ARG) and their similarity distances are calculated with Nested Earth Mover’s Distance (NEMD) algorithm. The calculation results and user survey show that the ARG and NEMD methods can reflect the visual similarity between generalised city models and the original ones.

  • 10.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    A Dynamic Typification Method of 3D City Models using Minimum Spanning Tree2010In: Proc. 6th international conference on Geographic Information Science, 2010Conference paper (Refereed)
    Abstract [en]

    A novel method based on MST for 3D City model typification is proposed. The 3D building models in higher LODs are converted into LOD1 with simplified ground plan and height. Minimum spanning tree (MST) of the ground plan centroid is generated and divided into sub-MSTs by road network. The building lists in each sub-MST with linear structure are selected, based on which typification model is created. According to the visualization evaluation and experiments, our method can reduce the building numbers while preserve the visual similarity well for selected city area.

  • 11.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    A multiple representation data structure of 3D building textures2011Conference paper (Other academic)
    Abstract [en]

    Texture is an important element for visualization of 3D city models and often takes a big proportion of the total data volume. In order to simplify 3D city model textures for dynamic visualization in different scales, a multiple representation data structure, TextureTree is proposed to store building textures in different LoDs. First, the texture image is iteratively segmented by horizontal or vertical dividing zone (edge or background from edge detection) until each sections are basically in the same color. Then textures in all sections are represented by their main color and the TextureTree is created based on the color difference between the adjacent sections. With the TextureTree, the simplified texture in different LoDs can be dynamically generated. The experiment results show that the data volume of building textures can be reduced by TextureTree while the required visual similarity is preserved.

  • 12.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Generalisation of textured 3D city models using image compression and multiple representation data structure2013In: ISPRS journal of photogrammetry and remote sensing (Print), ISSN 0924-2716, E-ISSN 1872-8235, Vol. 79, p. 68-79Article in journal (Refereed)
    Abstract [en]

    Texture is an essential part of 3D building models and it often takes up a big proportion of the data volume, thus makes dynamic visualization difficult. To compress the texture of 3D building models for the dynamic visualization in different scales, a multi-resolution texture generalization method is proposed, which contains two steps: texture image compression and texture coloring. In the first step, the texture images are compressed in both horizontal and vertical directions using wavelet transform. In the second step, TextureTreeis created to store the building color texture for the dynamic visualization from different distances. To generate TextureTree, texture images are iteratively segmented by horizontal and vertical dividing zone, e.g. edge or background from edge detection, until each section is basically in the same color. Thentexture in each section is represented by their main color and the TextureTree iscreated based on the color difference between the adjacent sections. In dynamic visualization, the suitable compressed texture images or the TextureTree nodes are selected to generate the 3D scenes based on the angle and the distance between user viewpoint and the building surface. The experimental results indicate that the wavelet based image compression and proposed TextureTree can effectively represent the visual features of the textured buildings with much less data.

  • 13.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Online Visualisation of a 3D City Model Using CityGML and X3DOM2011In: Cartographica, ISSN 0317-7173, E-ISSN 1911-9925, Vol. 46, no 2, p. 109-114Article in journal (Refereed)
    Abstract [en]

    This article proposes a novel framework for online visualization of 3D city models. CityGML is used to represent the city models, based on which 3D scenes in X3D are generated, then dynamically updated to the user side with AJAX and visualized in WebGL-supported browsers with X3DOM. The experimental results show that the proposed framework can easily be implemented using widely supported major browsers and can efficiently support online visualization of 3D city models in small areas. For the visualization of large volumes of data, generalization methods and multiple-representation data structure should be studied in future research.

  • 14.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Harrie, Lars
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics (closed 20110301).
    A Framework of Online 3D City Visualization using CityGML and X3D2009In: The 6th International Symposium on Digital Earth, 2009Conference paper (Refereed)
    Abstract [en]

    In this paper, a novel framework based on CityGML and X3D is proposed to support visualization of 3D City Model through Internet. In the proposed framework, the CityGML files are first parsed to acquire the city model information. Citygml4j, an open source java API, is used for this parsing. Then, the X3D representation is generated based on the city model by the proposed algorithm which can dynamically create different 3D city models according to corresponding Levels of Detail (LOD). Finally, the 3D city scene in X3D format is displayed through Internet with java applet or other X3D viewers. The Java Applets are created using the Xj3D toolkit. The preliminary experiment shows that the framework can correctly and efficiently exhibit the3D city model via Internet.

  • 15.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Harrie, Lars
    Department of Physical Geography and Ecosystem Analysis, Lund University.
    A Multiple Representation Data Structure for Dynamic Visualisation of Generalised 3D City Models2011In: ISPRS journal of photogrammetry and remote sensing (Print), ISSN 0924-2716, E-ISSN 1872-8235, Vol. 66, no 2, p. 198-208Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel multiple representation data structure for dynamic visualisation of 3D city models, called CityTree, is proposed. To create a CityTree, the ground plans of the buildings are generated and simplified. Then, the buildings are divided into clusters by the road network and one CityTree is created for each cluster. The leaf nodes of the CityTree represent the original 3D objects of each building, and the intermediate nodes represent groups of close buildings. By utilizing CityTree, it is possible to have dynamic zoomfunctionality in real time. The CityTree methodology is implemented in aframework where the original city model is stored in CityGML and the CityTree is stored as X3D scenes. A case study confirms the applicability of the CityTree for dynamic visualisation of 3D city models.

  • 16.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Fan, Hongchao
    Harrie, Lars
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Meng, Liqiu
    City Model Generalization Quality Assessment using Nested Structure of Earth Mover’s Distance2010Conference paper (Other academic)
    Abstract [en]

    To evaluate the quality of city model generalization, an attributed relational graph (ARG) is used to represent the features of city models and Nested structure of Earth Mover's Distance (NEMD) is employed to calculate the visual similarity of the ARGs. The experiments show that the proposed method is coherence with user survey result.

  • 17.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Harrie, Lars
    Department of Physical Geography and Ecosystem Analysis, Lund University.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    Detection and typification of linear structures for dynamic visualization of 3D city models2012In: Computers, Environment and Urban Systems, ISSN 0198-9715, E-ISSN 1873-7587, Vol. 36, no 3, p. 233-244Article in journal (Refereed)
    Abstract [en]

    Cluttering is a fundamental problem in 3D city model visualization. In this paper, a novel method for removing cluttering by typification of linear building groups is proposed. This method works. in static as well as dynamic visualization of 3D city models. The method starts by converting building models in higher Levels of Details (LoDs) into LoD1 with ground plan and height. Then the Minimum Spanning Tree (MST) is generated according to the distance between the building ground plans. Based on the MST, linear building groups are detected for typification. The typification level of a building group is determined by its distance to the viewpoint as well as its viewing angle. Next, the selected buildings are removed and the remaining ones are adjusted in each group separately. To preserve the building features and their spatial distribution, Attributed Relational Graph (ARC) and Nested Earth Mover's Distance (NEMD) are used to evaluate the difference between the original building objects and the generalized ones. The experimental results indicate that our method can reduce the number of buildings while preserving the visual similarity of the urban areas.

  • 18.
    Mao, Bo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Harrie, Lars
    Department of Physical Geography and Ecosystem Analysis, Lund University.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Fan, Hongchao
    Department of Cartography, Technical University of Munich.
    Real time visualisation of 3D city models in street view based on visual salienceIn: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824Article in journal (Refereed)
    Abstract [en]

    Street level visualization is an important application of the 3D city models. Challenges in the street level visualization are the cluttering of the detailed buildings and the performance. In this paper, a novel method for street level visualization based on visual salience evaluation is proposed. The basic idea of the method is to preserve these salient buildings in a view and remove the non-salient ones. The method is composed by pre-process and real-timevisualization. The pre-process starts by converting 3D building models in higher Levels of Detail (LoDs) into LoD1 with simplified ground plan. Then a number of index view points are created along the streets; these indexes refer both to the positions and the direction of the sights. A visual salience value is computed for each visible simplified building in respective index. The salience of the visible building is calculated based on the visual difference of the original and generalized models. We propose and evaluate three methods for visual salience: local difference, global difference and minimum projection area. The real-time visualization process starts by mapping the observer to its closest indexes. Then the street view is generated based on the building information stored in theindexes. A user study shows that the local visual salience gives better result than the global and area, and the proposed method can reduce the number of loaded building by 90% while still preserve the visual similarity with the original models.

  • 19. Wu, Z.
    et al.
    Cao, J.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Wang, Y.
    Semi-SAD: Applying semi-supervised learning to shilling attack detection2011In: RecSys - Proc. ACM Conf. Recomm. Syst., 2011, p. 289-292Conference paper (Refereed)
    Abstract [en]

    Collaborative filtering (CF) based recommender systems are vulnerable to shilling attacks. In some leading e-commerce sites, there exists a large number of unlabeled users, and it is expensive to obtain their identities. Existing research efforts on shilling attack detection fail to exploit these unlabeled users. In this article, Semi-SAD, a new semi-supervised learning based shilling attack detection algorithm is proposed. Semi-SAD is trained with the labeled and unlabeled user profiles using the combination of naïve Bayes classifier and EM-λ, augmented Expectation Maximization (EM). Experiments on MovieLens datasets show that our proposed Semi-SAD is efficient and effective.

  • 20. Wu, Z.
    et al.
    Mao, Bo
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Cao, J.
    MRGIR: Open geographical information retrieval using MapReduce2011In: Proc. - Int. Conf. Geoinformatics, Geoinformatics, 2011Conference paper (Refereed)
    Abstract [en]

    City objects recommendation based on characteristics of users, location, time and weather is a challenging issue in geographical information retrieval (GIR). In the meanwhile, city objects recommendation is a computation-intensive and data-intensive application. Cloud computing has gained significant attention in recent years to process the large volume of data. MapReduce framework is currently a most dominant technology in cloud computing. Augmented User-based Collaborative Filtering (AUCF) algorithm which can effective deal with hybrid variable types is proposed firstly. Then, MapReduce for GIR (MRGIR) is presented and AUCF is implemented within MRGIR as an example. The MRGIR is implemented in Hadoop which is an open source framework for MapReduce. Experimental results shows that with moderate number of map tasks, the execution time of GIR algorithms (i.e., AUCF) can be reduced remarkably.

1 - 20 of 20
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf