Calibration of ALS Intensity Data
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
With general advancements in computer technology and development ofdirect geo-referencing technology, such as GPS, airborne laser scanningsystems came into widespread use especially after 2002. In spite of relativelyhigh cost of purchase, the systems proved to be cost effective, providing fastand in large volumes 3D geospatial data acquisition with unprecedentedaccuracy and relatively modest processing complexity. Country-widecollection of laser scanning data, mainly due to DTM derivation, is becomingan attractive possibility for mapping. Since 2009, Swedish Government hasapproved and financed the project of developing the New National ElevationModel (NNH) for the country of Sweden, with aspects of monitoring climatechanges and other environmental impacts. The National Land Survey ofSweden, which is commissioned to carry out the project, is offering this highlyaccurate scanned data less expensive to secondary users, such as companiesspecialized in forestry applications, etc. Beside the geospatial data (X, Y, Z),laser systems additionally record the received signal intensity for eachmeasurement. So far, intensity values were just an additional variable, notused extensively, but in recent years many efforts have been made tounderstand and interpret these values. The wider use of intensity data ismissing due to the lack of techniques to calibrate them, so that theyrepresent values proportional to the scattering characteristics of the target. Inthe scope of this thesis it was examined which properties influence intensityvalues and to what degree. Already proposed methods for calibration weresummarized and the most suitable one was implemented based on the datafrom the NNH project and instruments used for it. The results proved to begood both empirically and visually, with reduced intensity variations over thesame targets. The potentials of using this corrected data are presented, suchas surface classification, automatic object recognition, multi-temporalanalysis, and more.
Place, publisher, year, edition, pages
2011. , 52 p.
, TRITA-GIT, ISSN 1653-5227 ; 11-006
ALS, Intensity, Calibration
IdentifiersURN: urn:nbn:se:kth:diva-38998ISRN: KTH/GIT/EX--11/006-SEOAI: oai:DiVA.org:kth-38998DiVA: diva2:438876
Subject / course
Degree of Master - Geodesy and Geoinformatics
2011-06-20, V33, Teknikringen 72, Stockholm, 13:15 (English)