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Dense DSMs from Stereo Imagery. IMAGE. Dr. Philippe Simard President SimActive Inc. About SimActive. Founded in 2003, SimActive is the developer of Correlator3D™ software, a patented end-to-end photogrammetry solution
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Dense DSMs from Stereo Imagery IMAGE Dr. Philippe Simard PresidentSimActive Inc.
About SimActive • Founded in 2003, SimActive is the developer of Correlator3D™ software, a patented end-to-end photogrammetry solution • SimActive has been selling Correlator3D™ to leading mapping firms and government organizations around the world • Correlator3D™ is the fastest commercial software to perform DSM generation DSM DTM Mosaic 3D Features
Correlator3D™ Software PROCESSING MODULES IMAGERY EO Refinement Satellite Aerial DSM Generation GeoEye Microsoft Ultracam DTM Extraction Worldview Intergraph Z/I DMC DEM Editing ALOS Prism Applanix DSS Cartosat-1 DiMAC Orthorectification Ikonos ADS80 Mosaic Creation Quickbird VM A3 Mosaic Editing SPOT Scanned Films Feature Extraction
DSM Generation What is it? • A Digital Surface Model (DSM) is a representation of ground topography • Main Processing Steps: • 1. Correlation • 2. Triangulation • Bottom-up approach DSM Example
Triangulation • Correlation DSM Generation Traditional approach: How does it work? P P Epipolar P11 P12 P13 Y Y’ Focal point Z’ Z X X’ Image 1 Image 2
Dense DSM Generation What is it? • A dense DSM has a grid post spacing approaching the ground sampling distance (GSD) of the input imagery SimActive has just released its next generation DSM engine capable of producing dense DSMs DSM Dense DSM
Challenges For dense DEM generation 1. Correlation • Process more difficult 2. Sensitivity • Radiometry differences between images • Camera calibration • Exterior orientation 3. Density • More points leads to longer processing time
Comparison SimActive Traditional • Top-Down • Test solutions • Grid-Based • High density in all areas • GPU • Hundreds of cores • Bottom-Up • Derive solution • Feature-Based • High density in some areas only • CPU • Few cores
Top-Down Idea: test solutions and check whether they solve the correlation problem P15 P14 P P11 P12 P13 Focal point Image 1 Image 2
Grid-Based Grid-based DEM is dense everywhere • No interpolation • Correlation performed on all points in the grid • Adjacent solutions assist each other
GPU Possible Solutions Processing Results GPU Cores P11 P21 ... Pn1 P12 P22 ... Pn2 ... P1n ... P2n ...Pnn 1 2 3 • Many possible solutions are prepared to be tested 1 • These solutions are processed by the GPU simultaneously 2 • When a match is found, the problem is solved 3
Results Close to 3x more points generated Resolution: 15 cm Accuracy: 5 cm Resolution: 25 cm Accuracy: 5 cm Dense DSM DSM
Benefits • World’s fastest commercially available DSM engine • Direct DSM result removing the need to convert from a point cloud • More points in low texture areas • DSM precision is consistent and homogeneous Dense DSM
Applications True Ortho Dense DTM 3D Features
Thank You Official Reseller Groupe SCE India Mahesh Nagendra J Mobile: +91 9900095741 mahesh@sce.co.in Dr Philippe Simard President SimActive Inc. psimard@simactive.com www.simactive.com