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Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
Gamma software introduction
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Gamma software introduction

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Brief introduction of Gamma software

Brief introduction of Gamma software

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  • 1. Documentation – User’s Guide GAMMA Software Introduction Version 1.0 – November 2006GAMMA Remote Sensing AG, Worbstrasse 225, CH-3073 Gümligen, Switzerland tel: +41-31-951 70 05, fax: +41-31-951 70 08, email: gamma@gamma-rs.ch
  • 2. GAMMA Software - Introduction Table of contentsINTRODUCTION ................................................................................................................................................... 3HARDWARE REQUIREMENTS ............................................................................................................................... 5GETTING STARTED WITH THE GAMMA SOFTWARE ........................................................................................... 5CONTACT POINT .................................................................................................................................................. 6PACKAGES OF THE GAMMA SOFTWARE ............................................................................................................ 7MSP.................................................................................................................................................................... 7ISP...................................................................................................................................................................... 9DIFF&GEO...................................................................................................................................................... 10LAT .................................................................................................................................................................. 11IPTA................................................................................................................................................................. 12DISP ................................................................................................................................................................. 12BIBLIOGRAPHY ON GAMMA SOFTWARE ......................................................................................................... 14 -2-
  • 3. GAMMA Software - IntroductionIntroductionThe GAMMA SAR and Interferometry Software is a collection of programs that allowsprocessing of SAR, interferometric SAR (InSAR) and differential interferometric SAR(DInSAR) data for airborne and spaceborne SAR systems. The software supports the entireprocessing from raw data to high level products such as digital elevation models,displacement maps, point target analysis and landuse maps. The software is arranged inpackages, each dealing with a specific aspect of the processing (see Table 1). Table 1. GAMMA Software packages and field of application.Name of package Acronym Field of applicationModular SAR Processor MSP SAR processingInterferometric SAR ISP Interferometric SAR processingProcessorDifferential Interferometry Differential interferometric SAR DIFF&GEOand Terrain Geocoding processing and terrain geocoding Classification, filtering, extraction of sub-Land Application Tools LAT regions, statistical toolsInterferometric Point Target IPTA Point target analysisAnalysisIn addition to the MSP a motion compensation package (MOCOM) is available for rangecompressed data.For visualization of intermediate and final image products the GAMMA Software offers a setof tools included in the DISP package. The DISP package also offers the possibility togenerate overview images in SUNraster (*.ras) and bitmap (*.bmp) format.The packages can be purchased singularly or be combined depending on the user’s needs andapplications. A set of combinations with respect to specific processing chains, data productsand applications can be found in Table 2.Binary as well as source code licenses are available. For Universities a 40% discount on thetotal price applies. An evaluation license of the software is available upon request.Maintenance of the software includes software updates and technical support by e-mail.Ad hoc training can be ordered, either on an individual basis or for groups. In addition,training courses on SAR interferometry and on the use of the GAMMA Software are offeredon a regular basis. Training is held by GAMMA personnel. -3-
  • 4. Table 2. Recommended combination of GAMMA Software packagesProcess Package Combination Input Main Products Singe Look Complex (SLC) dataGeneration of SAR data MSP Raw data Multi-look intensity (MLI) data SLC dataTerrain geocoding and image registration GEO MLI data Terrain geocoded data (Digital Elevation Model) Interferogram Coherence mapGeneration of interferometric SAR data SLC data Multi-look intensities ISP + DIFF&GEO(including terrain geocoding) (Digital Elevation Model) Height map Differential interferogram Displacement map Interferogram Coherence mapGeneration of SAR and differential Raw data Multi-look intensitiesinterferometric SAR data (including terrain MSP + ISP + DIFF&GEO (Digital Elevation Model) Height mapgeocoding) Differential interferogram Displacement map LATAnalysis of data products, conversions, data Image data of enhanced quality, plots, (together with any of the previous Any datafiltering classification. value added products combinations) IPTA SLC dataPoint target analysis (highly recommended together with Point target height history (Digital Elevation Model) ISP + DIFF&GEO)
  • 5. GAMMA Software - IntroductionHardware requirementsThe GAMMA Software runs on any Unix or Linux system as well as on Win32-basedplatforms (W2K, Windows XP).Recommended OS is Linux. Any distribution should work as long as the GTK toolkit isversion 2.8.12 or higher. A nice free distribution is Ubuntu. Both 32- and 64-bit processorsare supported on Linux. On Windows and Solaris a 32-bit environment is needed. TheGAMMA Software is also known to run on OS-X and other *IX systems. However, at themoment OS-X binary versions of the software are neither shipped nor maintained. ContactGAMMA if you have special needs.All PCs purchased with a 3 GHz+ clock today will run the GAMMA Software. It isrecommended to have one or preferably two sufficiently large hard disks (recommended: >200+ GB). Serial ATA disks allow much faster access than the older IDE disks. More RAMincreases the efficiency too. The software is designed to run with little RAM but at least 2-3GB are recommended especially for the memory intense processing steps (phase unwrapping,geocoding of large areas etc.). A video board with enough RAM (128 MB +) helps to speedup the visualization of large images.Getting started with the GAMMA SoftwareThe procedure to follow to install the GAMMA Software depends on the operating systemand whether source code or binaries have been delivered.• For the installation under MS WIN32 OS systems (NT4, Win2000, XP) follow the instructions described in the file INSTALL.WIN32 delivered with the software.• For the installation of BINARY SOFTWARE DISTRIBUTIONS follow the instructions described in the file INSTALL.BINARY (Linux/Unix) delivered with the software.• For the installation of SOURCE CODE SOFTWARE DISTRIBUTIONS follow the instructions in the file INSTALL.SOURCE delivered with the software.The GAMMA Software consists of executables that are started on the command line by theuser, by typing in the name of the specific program and using command line arguments asrequired (data files, metadata files, parameter values, external files). Each program performs aparticular step of a processing sequence. Programs can be arranged into scripts, which havethe advantage of automating the processing operations. Several scripts to carry out typicalprocessing steps are provided with the software. Demos including documented examples ofscripts to perform typical SAR and interferometric SAR processing are also provided.For an overview of the functionality of an individual program and its syntax, the user can typethe name of the program on the command line. More information is provided in the softwaredocumentation.For each package of the GAMMA Software the documentation consists of a User’s Guide anda Reference Manual. The User’s Guide provides a brief description of the processing -5-
  • 6. GAMMA Software - Introductionpossibilities offered by the package, the programs available in the package and examples oftypical data processing. The Reference Manual is intended to help the user with specificdocumentation on individual programs. It also clarifies the metadata structure adopted forimage data description.The data files produced by the GAMMA Software are mostly raster files of data in float orshort format. Related metadata are stored in text files. GAMMA data formats are kept assimple as possible for easy exchange between GAMMA Software and auxiliary software.Overall, the design philosophy has been to achieve accurate processing of the data, while stillpermitting processing of the data on a workstation computer in a reasonable amount of time.Contact pointFor questions or comments, please contact us:gamma@gamma-rs.chGAMMA REMOTE SENSING AGWorbstrasse 2253073 Gumligen, SwitzerlandTel: +41 31 951.70.05FAX: +41 31 951.70.08or visit the website http://www.gamma-rs.ch where you can also find further information onthe software, examples of processed data and value-added products, related technicaldocuments, recent news and information on forthcoming training courses. -6-
  • 7. GAMMA Software - IntroductionPackages of the GAMMA SoftwareIn the following a brief introduction to the functionality of the individual GAMMA Softwarepackages is provided. For more details please refer to the documentation obtained along withthe software.MSPThe Modular SAR Processor (MSP) is a system for deriving synthetic aperture radar imagesfrom raw SAR data from both airborne and spaceborne sensors. The MSP calculates from rawdata single look complex (SLC) and multi-look intensity (MLI) images in radar slantrange/Doppler coordinates. The processing includes radiometric calibration and is phasepreserving for interferometric processing.The main packages of the MSP are• preparation of raw SAR data in the GAMMA Software format for processing• pre-processing and data conditioning• range compression with optional azimuth prefiltering• autofocus• azimuth compression• multi-look post processing.A flow chart for the MSP is shown in Figure 1. For motion compensation of airborne data theadvanced motion compensation is required. -7-
  • 8. GAMMA Software - Introduction Data carrier with raw data and leaderfile Preprocessing and quality control • Raw data and leaderfile transcription • Extraction of parameters from leaderfile • Processor parameters definition • Range spectrum estimation • Missing line detection and correction • Doppler ambiguity resolution • Doppler centroid estimation • Radio Frequency Interference (RFI) filtering • Time dependent processing parameters for the processing of long stripsRaw data Sensor Processing Quality control (fixed) parameter file parameter file data & plots Antenna diagram Range Doppler processing sequence • Range compression - Receiver gain variation compensation - Azimuth presum (for quick-look generation) • Autofocus (iterative application possible) • Azimuth compression - Secondary range migration - Relative calibration (incl. antenna diagram) Single look complex (SLC) SAR data Display tools multi-look intensity SAR data Figure 1. Flow chart of the MSP package. -8-
  • 9. GAMMA Software - IntroductionISPThe Interferometric SAR Processor (ISP) package encompasses a full range of algorithmsrequired for the generation of interferograms, height maps, coherence maps, and differentialinterferometric products. The ISP allows:• baseline estimation from orbit data• precision registration of interferometric image pairs• interferogram generation (including common spectral band filtering)• removal of flat Earth phase trend• estimation of interferometric correlation• adaptive filtering of interferograms• phase unwrapping• precision estimation of interferometric baselines from ground control points• generation of topographic height• image rectification and interpolation of interferometric height and slope mapsThe flow chart for a typical interferometric processing is shown in Figure 2. Quality controlprograms complement the main processing sequence. Data carrier with slc data and leaderfile or SLC data processed by MSP Preprocessing, quality control and image co-registration Interferogram generation • Common spectral band filtering in range and azimuth Complex interferogram Registered intensities • Optional baseline estimation from fringe rate and/or Coherence map registration offsets • Coherence estimation Phase unwrapping and height map generation • Optional adaptive filtering of interferogram • Phase unwrapping Unwrapped phases • Refined baseline modeling using height control points Heights in SAR geometry • Computation of heights and true ground-ranges Transformation of heights and other products Topographic height and to orthonormal coordinates other products in orthonormal geometry Figure 2. Flow chart of the ISP package. -9-
  • 10. GAMMA Software - IntroductionDIFF&GEOThe Differential Interferometry and Geocoding (DIFF&GEO) package is a collection ofprograms designed to support the differential interferometric processing of SAR data as wellas geocoding between range-Doppler coordinates and map projections. The reason forinclusion of these quite different processes into one package is that geocoding capability isrequired for 2-pass differential interferometry.Geocoding is the coordinate transformation between the coordinates of an imaging system, inthis case range-Doppler coordinates of the SAR, and orthonormal map coordinates.Geocoding is necessary to combine information retrieved by the imaging system (e.g. theSAR image and products derived from it) with information in map coordinates (e.g. a digitalelevation model, a landuse inventory, geocoded information from optical remote sensing,etc.). In addition inverse geocoding, i.e. the coordinate transformation from orthonormal mapcoordinates to the range-Doppler coordinates, is required for 2-pass differentialinterferometry, namely for the simulation of the interferometric phase (in range-Dopplercoordinates) from the DEM in map coordinates.Figures 3 and 4 show the flow chart of respectively the geocoding part and the differentialinterferometry part of the DIFF&GEO package. The selected approach is very flexible as itallows calculating the geocoding lookup table based on a DEM in map coordinates as well asbased on an interferometric height estimate in range-Doppler coordinates. A variety ofapproaches for 2-, 3-, and 4-pass differential interferometry are supported. The processingscheme showing the different approaches to differential interferometry is summarized inFigure 4.The DIFF&GEO package extends the functionality of the ISP. It is therefore recommendedthat it is used in combination with the ISP. DEM, dem_par DEM segment DEM products: (user defined resolution) • Local incidence angle • True pixel size • Layover-shadow map Initial geocoding lookup table. Simulated SAR intensity image. refinement step forward transformation SAR coordinates: SAR to MAP MAP coordinates: • Intensity, Coherence lookup table • DEM • Derived products backward transformation • DEM Products • InSAR products • Landuse inventory • Differential products inversion • GIS Layers • ... backward transformation • ... • Transformed products MAP to SAR • Transformed products from MAP coordinates lookup table from SAR coordinates forward transformationFigure 3. Flow chart of the geocoding part of the DIFF&GEO package. The topography may either be known in map or range-Doppler coordinates. - 10 -
  • 11. GAMMA Software - IntroductionFigure 4. Flow chart for differential interferometry processing methods. The selection of the appropriate method depends on the availability of a digital elevation model (DEM) and on the capability to unwrap theinterferometric phase (cpx stands for the complex interferograms, unw for the unwrapped phase image, sim_unw for the simulated unwrapped topographic phase calculated from the DEM). The processing chains for 3- and 4- pass differential interferometry are identical except that no additional registration step is required in the 3-pass approach if both interferometric pairs use the same scene as reference geometry.LATThe GAMMA Land Application Tools (LAT) package is a collection of programs designed tosupport data processing in the context of using SAR and SAR interferometry for landapplications. The LAT includes special programs for filtering, parameter estimation, and datavisualization. There are programs to select test areas, and to extract the correspondingsignatures. In addition, the LAT supports simple classification schemes and image mosaicing.More in detail, the LAT package includes programs for:• parameter estimation• test-area analysis• filtering• classification• data format conversion• visualization• mosaicing - 11 -
  • 12. GAMMA Software - IntroductionIPTAThe Interferometric Point Target Analysis (IPTA) package is a collection of tools to exploitthe temporal and spatial characteristics of interferometric signatures collected from pointtargets to accurately map surface deformation histories, terrain heights, and relativeatmospheric path delays. The analysis can be summarized as an iterative improvement of themodel parameters to achieve an optimal match to the observed interferometric phases. Theanalysis is done for a selected list of points which correspond to point target candidates,which dramatically improves efficiency and storage requirements. The flowchart of a typicalIPTA processing sequence is illustrated in Figure 5.The advantage of using point targets is that these do not exhibit geometric decorrelation suchas distributed targets, permitting a more complete use of the data as even pairs with very longbaselines can be interpreted, resulting in improved accuracies and temporal coverage. Animportant element of the IPTA is the analysis across the data stack, respectively in the timedimension. The IPTA is fully compatible with the other GAMMA Software packages -identical phase models are used and programs to convert between the raster and vector dataformats are included. Therefore it is easy to use IPTA in combination with traditional InSARtechniques and use in a synergetic way the strengths of the two methods combined.DISPEssential for making full use of the GAMMA Software is a set of tools that can display resultson the screen and produce raster image products for documentation and archive purposes. Theprograms within the Display Tools and Utilities (DISP) package are organized by data typeand display functionality. The DISP package is bundled with any of the individual GAMMASoftware packages. Supported input data include:• raw SAR data and byte images• single look complex and detected multi-look intensity SAR images• interferograms, unwrapped phase, and interferometric correlation• DEMs and interferometric height maps, showing both geographic and map-projection coordinates• differential interferometric products such as subsidence maps• display and editing of phase unwrapping flag files• 8- and 24-bit SUNraster and bmp image format filesWithin the DISP package there are also programs for display of multiple data sets, either bymerging the data, such as combining intensity and interferometric phase, or rapidly flickeringbetween images of the same type. Each screen display program can access the original datafiles to extract the data values at the cursor position. The cursor coordinates are calculated inmap projection coordinates when DEM or raster data are in a map projection format such asUTM. Graphical editing of the files used to support phase unwrapping is also supported.The screen display programs were developed using the open source GTK+ toolkit(http://www.gtk.org) that can be compiled to run both under the X or Win32 2000, XPgraphic environment. Therefore the user has the same display functionality if running either aLinux or Win32 operating system on an X86 compatible platform. - 12 -
  • 13. GAMMA Software - IntroductionThe screen display and raster image generation programs are parallel in terms of functionality.For example, the program for screen display of detected intensity images is called dispwr,while the program for generation of a raster image of the same data set is called raspwr. Mostof the raster image programs support multi-looking in both range and azimuth. The imagesproduced can be displayed using either the DISP programs or any other raster image fileviewer such as xv or Photoshop. Figure 5. Flow chart of a typical processing with the IPTA package. I1 and I2 stand for first and second iteration respectively. - 13 -
  • 14. GAMMA Software - IntroductionBibliography on GAMMA SoftwareWegmüller, U., and Werner, C. L., "GAMMA SAR processor and interferometry software,"Proceedings of 3rd ERS Symposium, Florence, 14-21 March, pp. 1687-1692, 1997.Wegmüller, U., Werner, C., and Strozzi, T., "SAR interferometric and differentialinterferometric processing," Proceedings of IGARSS98, Seattle, 6-10 July, pp. 1106-1108,1998.Werner, C., Wegmüller, U., Strozzi, T., and Wiesmann, A., "GAMMA SAR andinterferometric processing software," Proceedings of ERS-Envisat Symposium, Gothenburg,16-20 October, 2000.Werner, C., Strozzi, T., Wegmüller, U., and Wiesmann, A., "SAR geocoding and multi-sourceimage registration," Proceedings of IGARSS02, Toronto, 24-28 June, 2002.Werner, C., Wegmüller, U., Strozzi, T., and Wiesmann, A., "Processing strategies for phaseunwrapping for INSAR applications," Proceedings of European Conference on SyntheticAperture Radar EUSAR 2002, Cologne, 4-6 June, 2002.Werner, C., Wegmüller, U., Strozzi, T., and Wiesmann, A., "Interferometric point targetanalysis for deformation mapping," Proceedings of IGARSS03, Toulouse, 21-25 July, 2003.Werner, C., Wegmüller, U., Wiesmann, A., and Strozzi, T., "Interferometric point targetanalysis with JERS-1 L-band SAR data," Proceedings of IGARSS03, Toulouse, 21-25 July,2003. - 14 -

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