Digital photogrammetric analysis of the IMP camera images: Mapping the Mars Pathfinder landing site in three dimensions

This paper describes our photogrammetric analysis of the Imager for Mars Pa thfinder data, part of a broader program of mapping the Mars Pathfinder lan ding site in support of geoscience investigations. This analysis, carried o ut primarily with a commercial digital photogrammetric system, supported by our in-house Integrated Software for Imagers and Spectrometers (ISIS), con sists of three steps. (1) geometric control: simultaneous solution for refi ned estimates of camera positions and pointing plus three-dimensional (3-D) coordinates of similar to 10(3) features sitewide, based on the measured i mage coordinates of those features; (2) topographic modeling: identificatio n of similar to 3 x 10(5) closely spaced points in the images and calculati on (based on camera parameters from step 1) of their 3-D coordinates, yield ing digital terrain models (DTMs); and (3) geometric manipulation of the da ta: combination of the DTMs from different stereo pairs into a sitewide mod el, and reprojection of image data to remove parallax between the different spectral filters in the two cameras and to provide an undistorted planimet ric view of the site. These processes are described in detail and example p roducts are shown. Plans for combining the photogrammetrically derived topo graphic data with spectrophotometry are also described. These include photo metric modeling using surface orientations from the DTM to study surface mi crotextures and improve the accuracy of spectral measurements, and photocli nometry to refine the DTM to single-pixel resolution where photometric prop erties are sufficiently uniform. Finally, the inclusion of rover images in a joint photogrammetric analysis with IMP images is described. This challen ging task will provide coverage of areas hidden to the IMP, but accurate ra nging of distant features can be achieved only if the lander is also visibl e in the rover image used.