XXII ISPRS Congress 2012: Technical Commission VII

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Multivolume work

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/5: METHODS FOR CHANGE DETECTION AND PROCESS MODELLING]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: ON THE USE OF DUAL-CO-POLARIZED TERRASAR-X DATA FOR WETLAND MONITORING A. Schmitt, T. Leichtle, M. Huber, A. Roth

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 ON THE USE OF DUAL-CO-POLARIZED TERRASAR-X DATA FOR WETLAND MONITORING A. Schmitt, T. Leichtle, M. Huber, A. Roth German Aerospace Center (DLR), Earth Observation Center (EOC), Oberpfaffenhofen, D-82234 Wessling, Germany - (andreas.schmitt, tobias.leichtle, martin.huber, achim.roth)(g)dlr.de KEY WORDS: Environment, Land Cover, Dynamic, Change Detection, SAR, Algorithms, Multitemporal, Value-Added ABSTRACT: Today's SAR sensors provide a variety of different image modes particularly with regard to multipolarised acquisitions. Until now, each polarisation mode requires a special decomposition which is a severe drawback when designing processing chains. Therefore, a new description for multipolarized SAR data based on the well-known Kennaugh matrix was developed that enables the uniform description and processing of SAR data independent of its polarisation by separating backscattering strength from polarimetric information. This mathematical approach subsequently is extended to the processing of multitemporal SAR data in order to stabilize the polarimetric information over longer periods of time and to enhance temporal changes in the polarimetric backscattering. Because of the high sensitivity of the Kennaugh elements a novel multilooking technique based on the Gaussian pyramid is used that locally adapts the look factor and thus selects the optimal balance between radiometric accuracy and geometric resolution. This methodology is applied to two dual-co-polarized TerraSAR-X acquisitions over the RAMSAR testsite "Upper Rhine" in order to generate value-added products that help to map land cover and land cover changes in consequence of water level changes. The first results are very promising although the interpretation of the observed polarimetric changes is not yet validated. The aim of this paper is to present a further application of the (Differential) Kennaugh matrix which will be the kernel of a polarimetry and change detection processor to be implemented in the coming years. 1. INTRODUCTION This paper addresses the use of TerraSAR-X data in order to determine the extent and the spatial as well as the temporal variability of open water and flooded vegetation surfaces in wetlands. 1.1 Background Previous studies use either single- or quad-polarized (Brisco, 2011) data for wetland mapping. Single-polarized data is always available because it is still the standard mode of the common space-borne SAR sensors. Open water surfaces can be identified in SAR images by their low backscattering like it is done generating the water indication mask of the TanDEM-X mission (Wendleder, 2011). Flooded vegetation is expected to show a strong double-bounce backscattering. Unfortunately, the backscattering mechanism cannot be identified in single- polarized data sets. Therefore, the extent of flooded vegetation areas can only be estimated by their stronger backscattering in each (co-pol) channel (Hess, 1990). Quad-pol data enables the identification of several backscattering mechanisms. But, quad- pol data is not easy to acquire. Most SAR satellite sensors do not support the polarimetric mode at any user-defined time. As the quad-pol mode always effects a reduction of the imaged area and the resolution as well, this method is not suitable yet for large-area applications. Hence, we focus on dual-co- polarized data. The combination of the complex HH and VV allows the identification of two scattering mechanisms: surface and double-bounce. The reduction of image size and resolution is lower than using quad-pol data. Additionally, dual-co- polarized data is available at any time and in almost any mode with TerraSAR-X and several other sensors. 1.2 Methodology The two complex layers of the TerraSAR-X dual-polarized SSC product cannot directly be interpreted and have to be decomposed and geocoded. As all common polarimetric decompositions only concern quad-polarized data, a new Kennaugh matrix like decomposition has been developed (Schmitt, 2012). The decomposition produces four layers. The first comprises the total intensity of both layers, which is very low over open water surfaces. The second layer gives the intensity difference between surface and double-bounce scattering. Thus, high values in the second layer indicate a dominant double-bounce scattering while low values indicate a dominant surface scattering. The third layer includes the co-pol diattenuation which is represented by the intensity difference between the two measured channels. The fourth layer is negligible only holding complementary correlation information. All layers are normalized by the total intensity or the so-called Hyperbolic-Tangent-Normalization respectively so that their value range is reduced to ]-1,1[. Having a closed range the values can be saved in an integer format without clipping information at the upper or lower end. The chosen bit depth then only fixes the sampling which reaches its maximum near the centre and decreases towards higher deviations in both negative and positive direction. For display and interpretation reasons the Hyperbolic-Tangent-Scaling of Kennaugh elements can directly be transferred to the common unit decibel via the Inverse Hyperbolic Tangent function. The first layer represents the total intensity independent of the polarization state while the other layers represent the polarized contribution to the total intensity. Hence, intensity and polarimetric information can be evaluated separately.

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