Hi, The geotransform parameters are the same than in the ESRI wordfile. I tried once to understand how the parameters behave when the image is rotated and wrote an OpenOffice spreadsheet about that. You can have a try and play with the parameters. I hope I have understood it right. I was not so sure myself and therefore there are some unnecessary cells with forward and backward formulas just to verify the results.
http://latuviitta.org/documents/rotated_worldfile.ods -Jukka Rahkonen- G Seiffert wrote > Hi all from GDLA. > > Thanks for the opportunity to as a question. It's regarding the > Geotransform > Tutorial(https://gdal.org/tutorials/geotransforms_tut.html). Tried to > get info in the web but since this seems a tricky one, my searches failed. > > The tutorial only deals with the ideal case of 'North up' images, for > which GT(2) and GT(4) are zero. However, my images are 'East up' and > potentially 'any direction up' (underwater photomosaic surveys by ROV). > The rotation works with '90' for GT(2, 4). But the scaling seems > completely ignored. Any hint? If it would be easy, I assume your > tutorial would give an example for how to deal with "non-N-up' images, > but ... > > My pics are 1920x1080, with pixel resolution of 0.0015 (yes, 0.15cm per > pixel, we're flying just 3m above the bottom). > > In case I rotate the images prior to geotransform (in Photoshop), > geotransform works perfect, with GT(2, 4) = 0. Scaling spot on. I can > live with that for our last survey but I'm also looking for a solution > in case our survey heading cannot be 0, 90, 180, or 270, but has to be > something like 35° (due to bottom currents etc.). > > Best regards, any hint qappreciated, > Gerhard > > > > _______________________________________________ > gdal-dev mailing list > gdal-dev@.osgeo > https://lists.osgeo.org/mailman/listinfo/gdal-dev -- Sent from: http://osgeo-org.1560.x6.nabble.com/GDAL-Dev-f3742093.html _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev