Opened 11 months ago

Closed 11 months ago

Last modified 11 months ago

#6560 closed defect (fixed)

ASRP polar arc zone images are not correctly georeferenced

Reported by: steveb Owned by: warmerdam
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.

DatasetCell Size XCell Size YOrigin XOrigin Y
TEST0101100.0914539100.0914539-307480.946-179363.885
TEST0201100.0914539100.0914539115305.354153740.473
TEST0501100.0914539100.0914539-307480.946153740.473

Attachments (1)

ASRP_Polar_Test_Data.zip (459.6 KB) - added by steveb 11 months ago.
ASRP Polar Test Data

Download all attachments as: .zip

Change History (4)

Changed 11 months ago by steveb

Attachment: ASRP_Polar_Test_Data.zip added

ASRP Polar Test Data

comment:1 Changed 11 months ago by Even Rouault

Resolution: fixed
Status: newclosed

In 34457:

ASRP: fix georeferencing of polar arc zone images (patch by steveb, fixes #6560)

comment:2 Changed 11 months ago by Even Rouault

In 34458:

ASRP: fix georeferencing of polar arc zone images (patch by steveb, fixes #6560)

comment:3 Changed 11 months ago by Even Rouault

Component: defaultGDAL_Raster
Milestone: 2.1.1
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