טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentShtain Zachi
SubjectModels for Analyzing Spaceborne Laser Waveforms
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Sagi Filin
Full Thesis textFull thesis text - English Version


Abstract

Recent years have witnessed the emergence of laser altimetry as one of the leading technologies in providing detailed topographic analysis. Nonetheless, deep understanding of some fundamental elements about this technology is still lacking. This is specifically true for information extraction from the waveform of the returned energy pulse and its translation into information about topographic characterization, surfaces roughness, and even understory vegetation structure.

Such analysis becomes even more vital when waveforms are obtained by spaceborne platforms. Characterization of such systems with footprint size far wider than airborne ones necessitates designated algorithms for their analysis. One prominent example for such spaceborne systems is the Geoscience Laser Altimeter Systems (GLAS) mounted on board the Ice Cloud and land Elevation Satellite (ICESat) whose objectives were to track elevation changes of the Greenland and Antarctica's glaciers, but topographic information on other regions has been acquired as well. All of the raw and processed GLAS data provides globally accurate information of the land topography and of objects on it.

The proposed research aims at studying the utilization of spaceborne laser data as a means for obtaining topographic information. In this regards, it has two objectives: the first is studying the quality of the spaceborne data, and the second is the development of algorithms for extraction of detailed information from the acquired waveforms. As the ICESat mission is the first to offer high standard spaceborne laser data, this research may provide insight into the expected quality of future missions carrying laser systems on board. For the research, a large set of laser returns over Israel is being utilized and evaluated against data of wide spectrum as a reference, including: laser scanning data, and digital terrain models from a variety of sources. These data enable the development and analysis of data processing models and as well as validation the quality of the topographic data encapsulated in the GLAS measurements.