On 21 November 2012 12:06, Even Rouault <[email protected]> wrote: > Selon David Strip <[email protected]>: > >> The GDAL API tutorial describes this array as: >> >> adfGeoTransform[0]/* top left x */ >> adfGeoTransform[1]/* w-e pixel resolution */ >> adfGeoTransform[2]/* rotation, 0 if image is "north up" */ >> adfGeoTransform[3]/* top left y */ >> adfGeoTransform[4]/* rotation, 0 if image is "north up" */ >> adfGeoTransform[5]/* n-s pixel resolution */ >> >> The GDAL Data model page says >> Xgeo = GT(0) + Xpixel*GT(1) + Yline*GT(2) >> Ygeo = GT(3) + Xpixel*GT(4) + Yline*GT(5) >> where the GT[i]are the coeffs described above. >> >> From this I conclude that the rotations are not sin/cos of the rotation, but >> rather the sin/cos times the >> appropriate pixel size. Is that right, or did I miss something? > > Yes, for a pure rotation. If the [1], [2], [4] and [5] have no particular > relation, the matrix can represent a combination of scaling, rotation and > shearing. See http://en.wikipedia.org/wiki/Transformation_matrix
Isaac's "Improving the Documentation of Get/SetGeoTransform" post is worth checking too: http://lists.osgeo.org/pipermail/gdal-dev/2011-July/029449.html Best regards, -- Mateusz Loskot, http://mateusz.loskot.net _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
