Newly added in our recent 2.3 release of ASP is the utility ‘pc_align’. This utility implements the iterative closest point (ICP) algorithm through the use of libpointmatcher library. This allows users to align their ASP created DEM against previously trusted dense sources like SRTM, USGS NED, or GMTED. This same utility can be used to align a DEM to sparse source like GLAS, LOLA, or MOLA via input from CSV. The example shown right aligns a DEM created from World View 2 imagery (2 m/px) of the Cathedral Range in California to a prior existing USGS NED map (30 m/px). The top left slice is the ASP created DEM while the bottom right is the trusted reference. Processing Earth Observing images with Ames Stereo Pipeline [email protected] http://irg.arc.nasa.gov/ngt/stereo Affine Script: > stereo <image1> <image2> \ <camera1> <camera2> \ <output prefix> \ --alignment affineepipolar Get Ames Stereo Pipeline Aligning Output to a Trusted Source Science Accomplished with ASP Methods of Ingestion Map Projecting Script: > mapproject -t rpc <dem prior> <image1> <camera1> <mimage1> > mapproject -t rpc <dem prior> <image2> <camera2> <mimage2> > stereo <mimage1> <mimage2> \ <camera1> <camera2> \ <output prefix> <dem prior> Script: > pc_align --max-displacement <meters> <dem prior> <asp dem> \ --save-transformed-source-points -o pc/pc > point2dem -tr 2.0 -t_srs "projection" pc/pc-trans_source.tif Script: Reference against geoid > dem_geoid <dem> Reference against ellipsoid > dem_geoid <dem> \ --reverse-adjustment Vertical Datum Support Script: Follow QR code in top right corner or go to: http://irg.arc.nasa.gov/ngt/stereo to find download link for your specific OS. > Download StereoPipeline.tar.bz2 > tar xf StereoPipeline.tar.bz2 > export PATH=$PATH: \ StereoPipeline/bin Read the Manual! > open StereoPipeline/*.pdf or > gvfs-open StereoPipeline/*.pdf Ames Stereo Pipeline (ASP) has for a long time been able to create dense elevation models for Planetary Science on non-terrestrial bodies. Now we’ve adapted our tools for Earth Science and can process imagery from Digital Globe, GeoEye, Astrium, and anything else with an RPC model readable by GDAL. You can download ASP to perform your own work from our website by following the instructions bellow. ASP is Apache 2 licensed (free as in beer) and operates on most forms of Linux and OSX. It is suitable for operation on your computer, the head-less server, or your university cluster. Processing satellite imagery into a point cloud is performed with ASP’s ‘stereo’ command. It requires two images with different perspectives in NTF or any other image format. It also accepts XML metadata that describes a rigorous camera model that is often shipped with Digital Globe data. The stereo command will by default try to correlate, match all pixels between images, without modifying the input imagery. However that can take a lot of time and will possibly fail if there is a rotation or scale difference between images. Instead it is recommended that the input images be epipolar rectified using the “--alignment affineepipolar” option. An example of its effect is shown right. Alternatively, for difficult stereo pairs, ASP can use prior existing low resolution DEM for map projection. The stereo command is smart enough when generate its point cloud to reverse the projection arithmetic and then triangulate with the more rigorous camera model. By default, all data created by ASP is referenced against an ellipsoid model. For Earth data this is usually WGS84. However this is not ideal for watershed analysis as an ellipsoidal model does not correctly model the changes in gravity across the surface of the Earth. Instead the solution is to use geoid, a lumpy model that describes mean sea level in the absence of weather and tides. ASP provides a utility, ‘dem_geoid’, which can be used to reference data against the commonly used EGM96, NAVD88, or if processing Mars data, MOLA MEGDRA. Our team desires to make elevation products for all imagery. However we don't have the time or experience to apply ASP to all applications. This is why NASA offers ASP completely free. We hope to enable the scientific community access to additional measurements that couldn't be had otherwise due to cost or data volume. For examples of ASP used by the community, please follow the sources on the right. Check out "Monitoring changes in polar ice sheets and sea ice using airborne and satellite remote sensing" by Shean et. al. Friday morning, C51A-0498. Samantha E. Peel, Caleb I. Fassett, "Valleys in pit craters on Mars: Characteristics, distribution, and formation mechanisms", Icarus, Volume 225, Issue 1, July 2013 N.P. Hammond, C.B. Phillips, F. Nimmo, S.A. Kattenhorn, "Flexure on Dione: Investigating subsurface structure and thermal history", Icarus, Volume 223, Issue 1, March 2013 Watters, W. A., L. Geiger, and M. Fendrock. "Shape Distribution of Fresh Martian Impact Craters from High-Resolution DEMs." LPI Contributions 1719 (2013): 3081. Lefort, Alexandra, et al. "Inverted fluvial features in the Aeolis-Zephyria Plana, western Medusae Fossae Formation, Mars: Evidence for post-formation modification." Journal of Geophysical Research: Planets (1991–2012) 117.E3 (2012).