EduServ5 - Mapping with Synthetic Aperture Radar (SAR)
Instructors: Prof. Olaf Hellwich, Dr. Andreas Reigber, Anke Bellmann (TU Berlin)
Date: 21 May - 1 June 2007
Course Objectives
The aim of this course is to give an introduction to synthetic aperture radar (SAR) and its application in the mapping domain. This includes a tutorial about the synthetic aperture principle, i.e. image generation using matched filtering signal processing techniques, a discussion of the characteristics of SAR images of geo-relevant objects, and introductions to SAR interferometry and SAR polarimetry, as well as polarimetric interferometry.
The course finishes with a detailed interactive comparison of maps produced on the basis of optical and SAR image data. The course is directed to the geomatics student on the graduate level without requiring in-depth expertise in physics. The course enables the participant to understand the basics of the SAR technology and to probe further using textbooks and the current scientific literature.
Course Outline
Module 1 - Introduction to Synthetic Aperture Radar
SAR imaging geometry, range and azimuth resolution, coherent imaging resulting in the speckle effect, interaction between radiation and surface, i.e. the radiometric properties of imaged objects, matched filtering in spatial and frequency domain, focusing in range and azimuth direction, and the need for motion compensation in airborne SAR are explained.
Module 2 - SAR Interferometry
The geometric principle of SAR interferometry is introduced as a means of three-dimensional positioning of points in space. Starting with an explanation of the phase signal of a SAR data set we discuss the meaning of coherency in SAR interferometry and explain the permanent scatterer technique. The steps of interferometric processing are treated on an intermediate level.
Module 3 - SAR Polarimetry
Polarization of electromagnetic waves is explained using simple visual means easily understandable to the non-physicist. On this basis we introduce scattering matrix, scattering vector, and polarimetric coherency matrix allowing to understand the SAR polarimetric signal as three-channel complex-valued data useful for landuse classification. Finally, we extend the SAR imaging paradigm to polarimetric interferometry allowing to reason about object reflectance characteristics in three-dimensional object space.
Module 4 - Mapping with SAR
The fourth and final module is dedicated to a specifically defined mapping task. After introducing the available data for several test areas the participant has to generate a map from SAR image data as well as from optical image data. The results produced by the participant are compared with reference data sets, and individual recommendations are given. Finally, results produced by professional participants of a contest previously executed are discussed.
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