matt.feemster <matt.feemster <at> ga-asi.com> writes:
> So my question involves three steps: > > 1) Is it possible to store only corner coordinates as a way of telling > GDAL/GeoTiff what the geo information is for a GeoTiff? Again, > transformations will not work here. Yes > 2) If it is possible, how to go about it? For example for a 10000x10000 pixel image gdal_translate source.tif output.tif -gcp 0 0 285113.632 6713217.584 -gcp 10000 0 284658.101 6703227.690 -gcp 0 10000 295103.322 6712761.873 -gcp 10000 10000 294647.828 6702772.378 Note that the anchor point of GDAL gcp is the top-left corner of the pixel and counting X and Y starts from zero. Therefore in this example X and Y values 10000 are used even that means binding gcp to a pixel that is just outside the image. If you have measured control points from the centers of pixels you may need to calculate also half a pixel shifts here and there. > 3) When assigning the GCPs, what exactly do the 'x' and 'y' members of the > GDAL_GCP structure mean? Per the documentation: X position of GCP in > georeferenced space. Are x and y a lat/lon pair? ECEF x/y? UTM > easting/northing? What exactly should I be assigning these values. X is easting or longitude, Y is northing or latitude. -Jukka Rahkonen- _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
