XXII ISPRS Congress 2012: Technical Commission VII

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Persistent identifier:: 1663813779

Title:: XXII ISPRS Congress 2012

Sub title:: Melbourne, Australia, 25 August-1 September 2012

Year of publication:: 2013

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663813779

Language:: English

Additional Notes:: Kongress-Thema: Imaging a sustainable future

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Document type:: Multivolume work

Volume

Persistent identifier:: 1663821976

Title:: Technical Commission VII

Scope:: 546 Seiten

Year of publication:: 2013

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663821976

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(39,B7)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist ermittelt.; Literaturangaben

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

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [VII/2: SAR INTERFEROMETRY]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: TOWARDS AN URBAN DEM GENERATION WITH SATELLITE SAR INTERFEROMETRY Cristian Rossi, Thomas Fritz, Michael Eineder, Esra Erten, Xiao Xiang Zhu and Stefan Gernhardt

Document type:: Multivolume work

Structure type:: Chapter

International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012 XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia Coherence Loss from Coregistration Mismatch Tr TT Tr EET oY 0:04 higher baselines higher incidence angles eo o e Coherence Loss e o m 0.0 lower baselines lower incidence angles i io bonn 80 TTTTTTTTI[TTTTTTTTITTTTTTTTTT[TTTTTITTT[TTTTTTTTI[TT ziii na uaa baa aaa 4 Height Difference (m) Figure 5: Coherence loss due to a coregistration mismatch in a typical TanDEM-X scenario. phase noise mitigation is evident comparing the two DEM por- tions. The height variance of the flat roof of the four buildings in the middle of the portion is 4.72 meters for the operational case and 0.68 meters for the experimental one. The improvement is great also for the phase unwrapping stage, necessary in this case due to the topography visible in Fig. 6. The combined use of the adaptively multilooked phase and the refined coherence in- creases dramatically the phase unwrapping quality ratio g,. This ratio expresses the percentage of the scene not affected by phase unwrapping errors (Rossi et al., 2012). Whereas in the opera- tional scenario q. — 7696, meaning that about one quarter of the scene is affected by phase unwrapping errors, in the experimental one q — 99.996, meaning that the adaptive processing totally solved the phase unwrapping issue. The false heights in the oper- ational scenario are caused by the very low coherent road at the center-left of the scene (Fig. 9). The interferometric phase of the road is highly noisy, creating several branch cuts. In the phase un- wrapping stage, the two sides of the road remains unconnected, creating an hight discrepancy between them of one phase cycles (35 meters). This problem is solved employing the adaptive mul- tilooking technique, as shown from the radargrammetric control maps (Rossi et al., 2012) in Fig. 10 and 11. Thus, the combined use of the enhanced phase and coherence in the employment and cost computation of the MCF algorithm provides a better result in the reduction of false heights generated by the phase unwrapping stage. The noise mitigation algorithms can be used also to reduce the theoretical DEM resolution. An example of Raw DEM over Berlin, processed with the region growing algorithm (Vasile et al., 2004), with a theoretical resolution of 2 meters, is shown in Fig. 12. The relative flatness of the scene allows the identification of a great amount of details from this two-dimensional view. À portion of the DEM over the city center is in Fig. 13. The height jumps over the river are caused by the adaptive multilooking algorithm. The height depressions are mostly shadow areas in the SAR image. Overall, buildings are well represented even at the imposed small resolution. 4 CONCLUSIONS AND FUTURE WORK This paper showed the potentials of TanDEM-X in the mapping of urban areas, globally acquired by the mission. Even if the operational Raw DEM has a coarse 12 meters resolution for a dense urban mapping, it has been showed through an applica- tion oriented algorithm how the mean absolute height accuracy 76 Figure 6: Interferometric phase of a portion of an acquisition over Las Vegas. In the black box the buildings under analysis. A E Figure 7: Three dimensional visualization of the DEM over Las Vegas for an industrial area generated using operational algo- rithms. of detected buildings in the Raw DEM is below 5 meters. Not considering the segmentation errors due to the geometrical decor- relations, the mean error drops below the meter and the standard deviation is kept below four meters. The building geolocalization accuracy has planned to be studied with the help of the Permanent Scatterer Interferometry high resolution technique. In the paper first examples of experimental high resolution urban Raw DEMs have been provided. The quality of the phase has been enhanced using the SAR amplitude statistics through adaptive multilooking techniques. The enhanced phase, together with the enhanced co- herence, helped the phase unwrapping stage. This enhancement allowed the generation of fine Raw DEMs having a theoretical resolution of just two meters. The absolute height and the geolo- cation validation of very high resolution DEMs are planned to be performed. Nonetheless, this paper didn’t analyze the limitations of the building reconstruction from a single aspect TanDEM ac- quisition. The greatest limitation to a urban three dimensional re-

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