Hi! I am new to GIS and polar projections and can't get my head around the GeoTransform of GDAL yet. >From an old post of Sean Gillies (http://sgillies.net/blog/39/gdal-warping-mola-topography/) a map projection info for a non-polar MOLA label like this: OBJECT = IMAGE_MAP_PROJECTION ^DATA_SET_MAP_PROJECTION = "DSMAP.CAT" MAP_PROJECTION_TYPE = "SIMPLE CYLINDRICAL" A_AXIS_RADIUS = 3396.0 <KM> B_AXIS_RADIUS = 3396.0 <KM> C_AXIS_RADIUS = 3396.0 <KM> FIRST_STANDARD_PARALLEL = "N/A" SECOND_STANDARD_PARALLEL = "N/A" POSITIVE_LONGITUDE_DIRECTION = "EAST" CENTER_LATITUDE = 0.0 <DEGREE> CENTER_LONGITUDE = 180.0 <DEGREE> REFERENCE_LATITUDE = "N/A" REFERENCE_LONGITUDE = "N/A" LINE_FIRST_PIXEL = 1 LINE_LAST_PIXEL = 720 SAMPLE_FIRST_PIXEL = 1 SAMPLE_LAST_PIXEL = 1440 MAP_PROJECTION_ROTATION = 0.0 MAP_RESOLUTION = 4.0 <PIXEL/DEGREE> MAP_SCALE = 14.818 <KM/PIXEL> MAXIMUM_LATITUDE = 90.0 <DEGREE> MINIMUM_LATITUDE = -90.0 <DEGREE> WESTERNMOST_LONGITUDE = 0.0 <DEGREE> EASTERNMOST_LONGITUDE = 360.0 <DEGREE> LINE_PROJECTION_OFFSET = 360.5 SAMPLE_PROJECTION_OFFSET = 720.5 COORDINATE_SYSTEM_TYPE = "BODY-FIXED ROTATING" COORDINATE_SYSTEM_NAME = "PLANETOCENTRIC" END_OBJECT = IMAGE_MAP_PROJECTION END
leads according to Sean to a GeoTransform of: <GeoTransform>-180.0,0.25,0.0,90.0,0.0,-0.25</GeoTransform> but I can't figure out how he gets to these numbers. Could somebody please give me a jumpstart and get me the 6 numbers out of this polar label information and hopefully also explain how to get to the numbers? OBJECT = IMAGE_MAP_PROJECTION ^DATA_SET_MAP_PROJECTION = "DSMAP_POLAR.CAT" MAP_PROJECTION_TYPE = "POLAR STEREOGRAPHIC" A_AXIS_RADIUS = 3376.2 <KM> B_AXIS_RADIUS = 3376.2 <KM> C_AXIS_RADIUS = 3376.2 <KM> FIRST_STANDARD_PARALLEL = 'N/A' SECOND_STANDARD_PARALLEL = 'N/A' POSITIVE_LONGITUDE_DIRECTION = "EAST" CENTER_LATITUDE = -90.0 <DEGREE> CENTER_LONGITUDE = 'N/A' REFERENCE_LATITUDE = 'N/A' REFERENCE_LONGITUDE = 'N/A' LINE_FIRST_PIXEL = 1 LINE_LAST_PIXEL = 12288 SAMPLE_FIRST_PIXEL = 1 SAMPLE_LAST_PIXEL = 12288 MAP_PROJECTION_ROTATION = 0.0 MAP_RESOLUTION = 512.0 <PIXEL/DEGREE> MAP_SCALE = 0.115 <KM/PIXEL> MAXIMUM_LATITUDE = -73.15 <DEGREE> MINIMUM_LATITUDE = -90.00 <DEGREE> WESTERNMOST_LONGITUDE = 'N/A' EASTERNMOST_LONGITUDE = 'N/A' LINE_PROJECTION_OFFSET = 'N/A' SAMPLE_PROJECTION_OFFSET = 'N/A' COORDINATE_SYSTEM_TYPE = "BODY-FIXED ROTATING" COORDINATE_SYSTEM_NAME = "PLANETOCENTRIC" END_OBJECT = IMAGE_MAP_PROJECTION END If someone has a link to some background literature i should read to find out myself, I also would be very thankful. Thanks and best regards, Michael
