Dave, You said that you have lat/lon values for each pixel. Can you explain?
On Fri, Jul 20, 2012 at 8:44 PM, David Hoese <dho...@gmail.com> wrote: > I'm attempting to put aircraft scan data into geotiffs (1-3 scanlines > each) and then use gdal_merge.py to combine them into one large geotiff > that has the entire aircraft's path. The scan lines are 15 pixels wide and > taken every 10 seconds, the geotiffs are wgs84 lat/lon, and I have lat/lon > values for each pixel. To handle the case when the aircraft isn't flying > straight north I think I have to use the 2 rotation parameters in the > affine geotransform, is that right? I don't have any test cases, but I > think if I don't use rotation anything that reads the geotiff will think > that the image is square(aligned) in lat/lon space. > > Whether or not I need to use this, can someone explain to me how to use > the rotation coefficients? What are the actual values of the coefficients > supposed to be? I couldn't find a good example and I couldn't get any > basic situations to make sense, like a 2x3 array turned 45 degrees. I used > these equations: > > Xgeo = GT(0) + Xpixel*GT(1) + Yline*GT(2) > Ygeo = GT(3) + Xpixel*GT(4) + Yline*GT(5) > > > And lastly, does gdal_merge.py handle rotation? I checked the source and > it doesn't ever seem to use elements 2 and 4 in its calculations. > > Thanks for any help. > > -Dave > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev > -- Best regards, Chaitanya kumar CH. +91-9494447584 17.2416N 80.1426E
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