ULTRAHIGH RESOLUTION TOPOGRAPHIC MAPPING OF MARS WITH HIRISE
STEREO IMAGES: METHODS AND FIRST RESULTS
R.L. Kirk1, E. Howington-Kraus1, M.R. Rosiek1, D. Cook1, J. Anderson1, K. Becker1, B.A. Archinal1, L. Keszthelyi1, R. King2, A.S. McEwen2
1 - U.S. Geological Survey, Astrogeology Program, Flagstaff,
Arizona, USA
2 - University of Arizona, Lunar and Planetary Laboratory,
Tucson, Arizona, USA
rkirk@usgs.gov
The Mars
Reconnaissance Orbiter (MRO) arrived at Mars on 10 March 2006 and began its
primary science phase in November. The
High Resolution Stereo Imaging Experiment (HiRISE) on MRO is the largest, most
complex camera ever flown to another planet.
Plans call for this scanner to image roughly 1% of Mars by area at a
pixel scale of 0.3 m during the next Mars year.
Among the thousands of images will be ~1000 stereopairs that will
provide an unprecedented three-dimensional view of the Martian surface at meter
scale. These stereopairs will provide a
tremendous amount of information for focused scientific studies, landing site
selection and validation, and the operation of future landers and rovers. In this paper, we describe our approach to
generating geodetically controlled digital topographic models (DTMs) from such
stereopairs, our first results, and plans for future DTM production.
Our
approach to the photogrammetric processing of HiRISE images follows that which
we have previously described for the MOC and the Mars Express High Resolution
Stereo Camera (HRSC). We use the USGS
in-house digital cartographic software ISIS to do initial processing, including
ingestion, decompression, and radiometric calibration of the images. "Three-dimensional" photogrammetric
processing steps, including control and DTM creation and editing, are performed
on a photogrammetric workstation running the commercial software SOCET SET (®
BAE Systems). Noteworthy departures from
past practice are the use of ISIS 3, the object-oriented successor to the older
ISIS 2 system, and pre-processing in ISIS to correct geometric complications of
the HiRISE images that cannot be modelled in the SOCET sensor model: multiple
CCD detectors in the focal plane, optical distortion around an axis far from
the detectors, and (ultimately) the small "jitter" motions of
spacecraft pointing that distort the images and hence the DTMs.
The first
HiRISE stereopair analyzed covers the location of the Opportunity rover near
the 750-m crater Victoria in Meridiani planum.
This scene is extremely unfavorable for automated stereomatching, with
extensive areas that are almost featureless, extremely steep, or both. These problems are offset by the high quality
of the HiRISE imagery, permitting us to obtain a 1 m/post DTM that required
only limited interactive editing. Future
mapping of the Spirit rover site, potential landing sites for the Phoenix
mission, and a variety of scientifically interesting targets, all of which have
much more surface texture that will facilitate stereomatching, are likely to
proceed even more successfully.