VO1/VO2 MARS VISUAL IMAGING SUBSYSTEM DIGITAL TERRAIN MODEL

This digital image map of Mars is a cartographic extension of a previously released set of CDROM volumes containing individual Viking Orbiter Images (PDS volumes VO_1001, VO_1002, etc.). The data in the latter are pristine, in the sense that they were processed only to the extent required to view them as images. They contain the artifacts and the radiometric, geometric, and photometric characteristics of the raw data transmitted by the spacecraft. This new volume set, on the other hand, contains cartographic compilations made by processing the raw images to reduce radiometric and geometric distortions and to form geodetically controlled Mosaicked Digital Image Models (MDIMs). (Because the photometric processing used in this MDIM was oversimplified, quantitative radiometric analysis on this data is not possible.) It also contains digitized versions of an airbrushed map of Mars as well as a listing of all IAU-approved feature names. In addition, special geodetic and photogrammetric processing has been performed to derive rasters of topographic data, or Digital Terrain Models (DTMs). The latter has a format similar to that of the MDIM, except that elevation values are used in the array instead of image brightness values. The Mars DTM exists in its entirety on Volume 7. Finally, Volume 7 has a listing of SPICE files derived for the Viking images used in the MDIM and the DTM. These files contain updated camera orientation matrices for each of the frames. The matrices are by-products of the photogrammetric processing for the control network required to compile the MDIM and the DTM.