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 along the elevation direction. It is located at the layover area. Fig.9 gives a closer look to the ground truth at that area. The left image shows the convention center visualized in Google Earth in which the pixel of interest is included in the area marked by a red block. The right image tells that the returns from the roof of the convention center and from the plaza near ground mainly contribute to the measurement of this pixel. Figure 8: TerraSAR-X intensity image of convention center, Las Vegas; selected pixel marked by green spot Figure 9: corresponding aerial image, © Google Earth Figure 10: Model of the ground truth for the pixel of interest For simulation, we simplify the ground truth to the following model as depicted in Fig. 10. The incidence angle for the acquisition is adapted to the real SAR acquisition and, hence, is 31.8 degrees. The taller building refers to the convention center which has a height of about 24m, while the lower building stands for the plaza near ground. Heights are measured over ground. The measurement for the pixel of interest refers to the integral of the returns from the objects included in the strip highlighted in blue color. For simulation purposes, two box models are used for modeling both the plaza and the convention center (Figure 11). The roughness of the plaza’s surface is assumed to be slightly higher than the roughness of walls and roof parts of the convention center. 3.2 Simulation vs. real data The reflectivity profile of the resolution cell along elevation direction is derived using the simulation concept described in Section 2. Pixel selection is adapted to extracted real data as shown in Figure 8. Afterwards, the resulting slice in elevation is displayed in height over ground geometry (Figure 12). Heights of reflecting objects are reliably extracted as two single bounce contributions at heights of 3 and 24 meters. Figure 11: 3D model scene containing two boxes for approximating layover effect (flat box: 20 m x 30 m x 3 m; tall box: 15 m x 15 m x 24 m); diffuse backscattering behaviour at all box surfaces Figure 12: discrete elevation coordinates for backscattering objects; step-width in elevation: 1 meter Fig. 13 shows the result of tomographic analysis for the corresponding position in real TerraSAR-X data. The reflection profile has been calculated with the approach described in (Zhu et al., 2008). As input data, 16 TerraSAR-X spotlight images with an across-track baseline range of 270m have been used. The peaks in reflection profile show nice correspondence with the simulated results, which underlines the accurate geometric properties of the simulation. However, it has to be noted that accurate estimation of intensity proportions is not possible as ground truth for surface properties was not available. At this point, simulated intensity values only indicate a stronger diffuse backscattering from the plaza which is also visible in the reflectivity map extracted from real SAR data. Enhanced information about the scattering behaviour of the plaza and the convention center may enable better simulation results in the

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