8.10. Mars Express High Resolution Stereo Camera (HRSC)¶
The HRSC camera on the Mars Express satellite is a complicated system, consisting of multiple channels pointed in different directions plus another super resolution channel. The best option to create DEMs is to use the two dedicated stereo channels. These are pointed ahead of and behind the nadir channel and collect a stereo observation in a single pass of the satellite. Data can be downloaded from the Planetary Data System (PDS) http://pds-geosciences.wustl.edu/missions/mars_express/hrsc.htm or you can use the online graphical tool located at http://hrscview.fu-berlin.de/cgi-bin/ion-p?page=entry2.ion. Since each observation contains both stereo channels, one observation is sufficient to create a DEM.
HRSC data is organized into categories. Level 2 is radiometrically corrected, level 3 is corrected and mapprojected onto MOLA, and level 4 is corrected and mapprojected on to a DEM created from the HRSC data. You should use the level 2 data for creating DEMs with ASP. If you would like to download one of the already created DEMs, it may be easiest to use the areoid referenced version (.da4 extension) since that is consistent with MOLA.
What follows is an example for how to process HRSC data. One starts by fetching the two stereo channels from:
You may need to download the HRSC kernel files in case using
spiceinit does not work. You will also probably
need to include the
ckpredicted=true flag with
images are large and may have compression artifacts so you should
experiment on a small region to make sure your stereo parameters are
working well. For this frame, the MGM stereo algorithm performed better
than block matching with subpixel mode 3.
ISIS> hrsc2isis from=h1995_0000_s12.img to=h1995_0000_s12.cub
ISIS> hrsc2isis from=h1995_0000_s22.img to=h1995_0000_s22.cub
ISIS> spiceinit from=h1995_0000_s12.cub ckpredicted=true
ISIS> spiceinit from=h1995_0000_s22.cub ckpredicted=true
ISIS> parallel_stereo h1995_0000_s12.cub h1995_0000_s22.cub \
--stereo-algorithm 2 --cost-mode 3 mgm/out