#6560 closed defect (fixed)
ASRP polar arc zone images are not correctly georeferenced
Reported by: | steveb | Owned by: | warmerdam |
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Priority: | normal | Milestone: | 2.1.1 |
Component: | GDAL_Raster | Version: | 1.8.0 |
Severity: | normal | Keywords: | ASRP Polar Zones Azimuthal Equidistant Projection |
Cc: |
Description
When ASRP polar arc zone images are opened the affine transformation coefficients are not set correctly. The cell size is always set to 500m and the image origin to (-1152000, 1152000).
The following method can be used to calculate the affine transformation coefficients for polar arc zone images:
if( ZNA == 9) { // North Polar Case padfGeoTransform[0] = 111319.4907933 * (90.0 – PSO/3600.0) * sin(LSO * PI / 648000.0); padfGeoTransform[1] = 40075016.68558 / ARV; padfGeoTransform[2] = 0.0; padfGeoTransform[3] = -111319.4907933 * (90.0 – PSO/3600.0) * cos(LSO * PI / 648000.0); padfGeoTransform[4] = 0.0; padfGeoTransform[5] = -40075016.68558 / ARV; } else if (ZNA == 18) { // South Polar Case padfGeoTransform[0] = 111319.4907933 * (90.0 + PSO/3600.0) * sin(LSO * PI / 648000.0); padfGeoTransform[1] = 40075016.68558 / ARV; padfGeoTransform[2] = 0.0; padfGeoTransform[3] = 111319.4907933 * (90.0 + PSO/3600.0) * cos(LSO * PI / 648000.0); padfGeoTransform[4] = 0.0; padfGeoTransform[5] = -40075016.68558 / ARV; }
The method used is based on a sphere of radius 6378137m in accordance with the ASRP specification. In addition the polar zone coordinate system definitions will need to be modified as follows:
if( ZNA == 9 ) { osSRS = "PROJCS[\"ARC_System_Zone_09\",GEOGCS[\"GCS_Sphere\",DATUM[\"D_Sphere\",SPHEROID[\"Sphere\",6378137.0,0.0]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433]],PROJECTION[\"Azimuthal_Equidistant\"],PARAMETER[\"latitude_of_center\",90],PARAMETER[\"longitude_of_center\",0],PARAMETER[\"false_easting\",0],PARAMETER[\"false_northing\",0]]"; } if (ZNA == 18) { osSRS = "PROJCS[\"ARC_System_Zone_18\",GEOGCS[\"GCS_Sphere\",DATUM[\"D_Sphere\",SPHEROID[\"Sphere\",6378137.0,0.0]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433]],PROJECTION[\"Azimuthal_Equidistant\"],PARAMETER[\"latitude_of_center\",-90],PARAMETER[\"longitude_of_center\",0],PARAMETER[\"false_easting\",0],PARAMETER[\"false_northing\",0]]"; }
The attached zip file contains 3 ASRP polar test datasets. The cell size and origin of the test images are given in the following table.
Dataset | Cell Size X | Cell Size Y | Origin X | Origin Y |
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TEST0101 | 100.0914539 | 100.0914539 | -307480.946 | -179363.885 |
TEST0201 | 100.0914539 | 100.0914539 | 115305.354 | 153740.473 |
TEST0501 | 100.0914539 | 100.0914539 | -307480.946 | 153740.473 |
Attachments (1)
Change History (4)
Changed 15 months ago by
Attachment: | ASRP_Polar_Test_Data.zip added |
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comment:3 Changed 15 months ago by
Component: | default → GDAL_Raster |
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Milestone: | → 2.1.1 |
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ASRP Polar Test Data