CMRT09

Stilla, Uwe

Bibliographic data

Monograph

Persistent identifier:: 856955019

Author:: Stilla, Uwe

Title:: CMRT09

Sub title:: object extraction for 3D city models, road databases, and traffic monitoring ; concepts, algorithms and evaluation ; Paris, France, September 3 - 4, 2009 ; [joint conference of ISPRS working groups III/4 and III/5]

Scope:: X, 234 Seiten

Year of publication:: 2009

Place of publication:: Lemmer

Publisher of the original:: GITC

Identifier (digital):: 856955019

Illustration:: Illustrationen, Diagramme, Karten

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: RAY TRACING AND SAR-TOMOGRAPHY FOR 3D ANALYSIS OF MICROWAVE SCATTERING AT MAN-MADE OBJECTS S. Auer, X. Zhu, S. Hinz, R. Bamler

Document type:: Monograph

Structure type:: Chapter

In: Stilla U, Rottensteiner F, Paparoditis N (Eds) CMRT09. IAPRS, Vol. XXXVIII, Part 3/W4 — Paris, France, 3-4 September, 2009 RAY TRACING AND SAR-TOMOGRAPHY FOR 3D ANALYSIS OF MICROWAVE SCATTERING AT MAN-MADE OBJECTS S. Auer 3 , X. Zhu a , S. Hinz b , R. Bamler 3C 3 Remote Sensing Technology, Technische Universität München, Arcisstrasse 21, 80333 München - (Stefan.Auer, Xiaoxiang.Zhu)@bv.tum.de b Institute for Photogrammetry and Remote Sensing, Universität Karlsruhe, Kaiserstrasse 12, 76128 Karlsruhe - stefan.hinz@ipf.uni-karlsruhe.de c Remote Sensing Technology Institute, German Aerospace Center (DLR), Münchner Strasse 20, 82234 Oberpfaffenhofen-Wessling - Richard.Bamler@dlr.de Commission VI, WG VI/4 KEY WORDS: SAR Simulation, Ray Tracing, POV Ray, SAR Tomography, TerraSAR-X ABSTRACT: An inherent drawback of SAR imaging of complex 3D structures is the potential layover of more than one scatterer in one resolution cell. Such scatterers can be separated by tomographic processing of multiple SAR images acquired with different across-track baselines. Simulation tools may further support interpretation of such layover effects appearing in multi-body urban scenes. In this paper, an existing 2D simulation approach, developed for separating different kinds of reflection effects in the azimuth-range plane, is enhanced by including the elevation direction as third dimension and thus enabling the comparison of the SAR simulation results with 3D imaging techniques such as tomography. After introducing the simulation concept, tools for three-dimensional analysis of scattering effects are presented. Finally, simulated data are compared with real elevation data extracted from TerraSAR-X images for showing potential fields of application. 1. INTRODUCTION High resolution SAR sensors like TerraSAR-X or Cosmo- SkyMed provide SAR images having a resolution of below one meter in spotlight mode. While in SAR images of coarse resolution several dominant scatterers from man-made objects at slightly different ranges may be condensed into a single pixel, these will be separable in high resolution images. Hence, more image features can be distinguished due to an increased number of deterministic effects and due to an increased signal to clutter ratio for dominant scatterers (Adam et al., 2008). However, visual interpretation of image features in high resolution SAR images remains challenging due to range dependent geometrical effects. SAR maps the 3D world basically into a cylindrical coordinate system, where range and azimuth are the image coordinates and elevation is the coordinate, along which all scattering contributions are integrated, i.e. all scatterers are mapped into the same resolution cell in the azimuth-range plane if they have the same spatial distance with respect to the SAR sensor. Access to the third coordinate, elevation, is achieved by multi-baseline methods, like Persistent Scatterer Interferometry (Ferretti et ah, 2001; Kampes, 2006) or SAR tomography (Reigber & Moreira, 2000; Fomaro et al, 2003; Zhu et ah, 2008). Simulation of scattering effects for urban areas may support visual interpretation of high resolution SAR images. In this context, Franceschetti and co-workers (Franceschetti et ah, 1995) distinguish between two different kinds of SAR simulators: image simulators and SAR raw data simulators. In the past, different concepts have been presented for simulating artificial SAR images for urban areas (Balz, 2006; Mametsa et ah, 2001) and for simulating SAR raw data by illuminating simplified building models (Franceschetti et ah, 2003). The simulator presented in this paper applies ray tracing algorithms and has been developed for simulating artificial SAR reflectivity maps (Auer et ah, 2008). The approach is focused on geometrical correctness while physical effects and speckle effects are neglected. In addition to a reflectivity map containing all backscattered intensities, reflection effects are assigned to different image layers based on available bounce level infonnation, i.e. separate layers for single bounce, double bounce, etc. Hence, interpretation of deterministic reflection phenomena appearing at man-made objects is simplified. So far, for providing image data in azimuth and range, two out of three dimensions of the imaging system have been exploited. The novelty of the presented approach compared to other simulation concepts relates to the fact that the complete 3D geometry of the SAR imaging process is simulated and stored. This enables one, based on the simulated 2D SAR, to retrieve information about the existence of multiple scatterers in one resolution cell in the SAR image. We show that simulation of the distribution of point scatterers in elevation direction may support the interpretation of estimated elevation coordinates derived by SAR Tomography. The structure of the paper is organized as follows. Firstly, the basic simulation concept is introduced in Section 2 where four major parts of the simulation concept are explained including necessary developments for extraction and analysis of elevation data. Simulation results displaying elevation data are compared with real data extracted from a TerraSAR-X image in Section 3. Finally, in Section 4, a short summary is given and future work is addressed.

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