CCSD3ZF0000100000001NJPL3IF0PDS200000001 = SFDU_LABEL RECORD_TYPE = STREAM PRODUCT_CREATION_TIME = 2001-02-08 OBJECT = TEXT NOTE = "Anomalies and discrepancies in the CD Volume set." END_OBJECT = TEXT END Mission to Mars Mars Mosaicked Digital Image Model (MDIM) Errata This file describes anomalies, discrepancies, and additional updates regarding the MIDM CD collection. The contents of the files in the GAZETTER subdirectory on all volumes have not been updated since the production of Version 1. The tables include feature names approved by the International Astronomical Union up to 1991. Coordinates given for these features are based on the earlier version of the mosaic and so are not completely accurate with respect to the present product. By intention, the design of this CD is as similar as possible to that of Version 1. The following differences in CD contents and layout may be noted. This CD does not include Extended Attribute Records (XARs), which are needed in order to mount the disk and access the data on some operating systems such as VMS. The VMS system is not supported for this dataset. An EXTRAS directory has been added to the root directory and the POLAR directory containing Polar Stereographic projections of the data from 80 to 90 degrees latitude (volumes 1 and 6 only) has been moved to this directory. Also, the ISIS directory in EXTRAS contains a set of directories corresponding to those in the root directory and containing detached ISIS labels for each PDS image file. ISIS programs can be run by copying the detached label file and corresponding PDS image file to the same directory on hard disk and specifying the detached label as the value of the FROM parameter. The interpretation of paths to detached data in releases of ISIS after January 2001 is sufficiently flexible that ISIS programs can be run directly on the detached label file on CD when specified in the FROM parameter. Previous versions of ISIS do not have this capability. If it is the intention of the user to mosaic the ME (16 deg) tiles using ISIS, it is recommended that the user set MIN_VALS = 1 during execution of the GEOM program. Insufficient overlap among the 16 deg tiles results in single pixel gaps between mosaiked tiles when GEOM is allowed to default to a MIN_VALS = 4. The SOFTWARE directory present in Version 1 has been omitted from these disks. Users are directed to the PDS web pages at http://pds.jpl.nasa.gov/pds-cn-homepage.html where they may find the software inventory pages where NASAView display software can be obtained. The file IMGINDX.DBF has been omitted from the directory INDEX. This file contained the same information as IMGINDEX.TAB, formatted for use in the commercial database program Sybase, use of which is no longer supported. The information in the file IMGINDEX.TAB and in the labels of the individual image mosaic files has been updated and is correct, with the exception of the SOURCE_IMAGE_ID fields/keyvalue, which have been copied from Version 1. These fields contain the identifiers for the Viking Orbiter EDR images used to produce each piece of the image mosaic. They are accurate and nearly but not entirely complete. A limited number of additional Viking EDRs were added to this version of the mosaic to fill gaps found late in production, and do not appear in the image labels or IMGINDEX.TAB. The IMAGE_ID values for these added images are as follows: 075B06 079A24 093A56 097A84 248B82 248B84 259S56 350A17 352B69 368S11 368S12 368S13 368S14 368S15 372S43 387X12 387X14 408A12 431B62 444A03 472B14 491B54 494A54 494A56 494A69 519A07 555A23 583A56 583A58 646A26 682A22 682A24 684A42 694A76 694A77 694A78 694A80 729A13 750A20 759A63 829A45 888A03 888A07 888A08 888A09 Change in definition of the Projection offset parameters: We have changed the definition of the X_AXIS_PROJECTION_OFFSET and Y_AXIS_PROJECTION_OFFSET keyword parameters in order to correct a discrepancy with the PDS definition of these keywords. The changed definition of the projection offset parameters results in a slightly modified set of equations relating line and sample with latitude and longitude: line = INT(X_AXIS_PROJECTION_OFFSET - LAT*MAP_RESOLUTION) sample = INT(Y_AXIS_PROJECTION_OFFSET - (LON - CENTER_LONGITUDE)*MAP_RESOLUTION*COS(LAT)) The original Mars MDIM was used to compute line and sample position from latitude and longitude according to the following equations: line = INT(X_AXIS_PROJECTION_OFFSET - LAT*MAP_RESOLUTION + 1.0) sample = INT(Y_AXIS_PROJECTION_OFFSET - (LON - CENTER_LONGITUDE)*MAP_RESOLUTION*COS(LAT) + 1.0) Note that the addition of 1.0 was part of the equation. This means the X_AXIS_PROJECTION_OFFSET and Y_AXIS_PROJECTION_OFFSET are relative to line and sample 0,0 in the image array. Because the direction of positive longitude is to the west for Mars, there is a "-" after the Y_AXIS_PROJECTION_OFFSET in the equation. According to the PDS definition of these parameters the offset parameters are relative to line and sample position 1,1. Thus the addition of 1.0 is no longer required.