PROJECT NAME Columbia_Hills HIRISE SOURCE IMAGES PSP_001513_1655 PSP_001777_1650 TECHNICAL CONTACT INFORMATION NAME USGS-ASTROGEOLOGY INSTITUTION USGS-ASTROGEOLOGY Products are tied to MOLA elevations. Elevation range for this project: VALID_MINIMUM = -1954.39 m VALID_MAXIMUM = -1833.56 m SOCET SET NGATE was used to extract terrain. Post spacing in DTM is 1 m. Notes: The correct stretch parameters from pre-processing were not retained. In the orthoimages, the values for OFFSET and SCALING_FACTOR therefore do not convert back to I/F pixel values. KNOWN ARTIFACTS These are known artifacts present in some, but not all, HiRISE DTMs. They may not be present in this DTM! Look at the terrain shaded relief to detect these before using the DTM! - Boxes Some DTMs have square areas that are usually about .5-1 m different in elevation from the surrounding areas. These are artifacts of the processing algorithms used in Socet Set ((c) BAE Systems). There may be goups of these boxes. They are almost impossible to edit out, so the user should look for such artifacts in a terrain shaded relief map before using the DTM for analysis. - CCD seams A HiRISE image is made up of 10 individual images, stitched together along their long edges. In a DTM, these seams can be visible as long lines. These seams are difficult to remove from the whole - Faceted areas Areas that were very bland (low contrast) or deeply shadowed with low contrast and low signal may have a "faceted" look to them. Terrain in these areas is not trustworthy.