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I'm reading GeoTIFF and GDAL documentations and I'm trying to understand what type of transformations are supported.

transformations

GeoTIFF documentation says you can use ModelTransformationTag to define a transformation matrix, but later adds:

For Baseline GeoTIFF, the model space is always 2-D, and so the matrix will have the more limited form

And then goes on to describe a matrix that only supports 2D affine transformations.

Later in the document it seems to imply that non-affine projections are only supported via use of tiepoints, and still would not work with Baseline GeoTIFF images.

Case 5: The raster data cannot be fit into the model space with a simple affine transformation (rubber-sheeting required). Use only the ModelTiepoint tag, and specify as many tiepoints as your application requires. Note, however, that this is not a Baseline GeoTIFF implementation, and should not be used for interchange; it is recommended that the image be geometrically rectified first, and put into a standard projected coordinate system.

This seems to be confirmed in GDAL documentation, which describes SetGeoTransform, which is used to "set the affine transformation coefficients".

Does that mean there is no way of describing non-orthorectified images using GeoTIFF?

Is there some non-baseline GeoTIFF that supports non-affine (i.e. projective transformations)? If so, what software supports it?

Is there any other image format that natively supports projective transformations?

  • GDAL supports GCPs, see: gdal.org/gdal_datamodel.html#gdal_datamodel_dataset_gcp, not sure if that is what you are looking for though. – user10353 Mar 4 '16 at 22:55
  • I know, I mentioned it in my question, but referred to them as tiepoints (using GeoTIFF terminology). However, as I've also mentioned, it strangely says that "Baseline GeoTIFF" does not support using tiepoints with non-georectified images. So that takes me back to my questions. – naktinis Mar 5 '16 at 1:10
  • What exactly are you trying to do? Do you need to store the GCP info, or just use it for warping? – user10353 Mar 8 '16 at 23:27
  • @kyle, I have images which are taken from an aircraft. They are not necessarily taken orthogonally to earth's surface, but I know camera's orientation angles and position w.r.t. to earth. I have no GCPs (think images covering hundreds of kilometres). I want to take an image like that and save it as GeoTIFF (or any other georeferenced format) so that all georeferencing information is stored inside the image file and I can, for example, simply open that image in Google Earth, or any other common mapping software and it would be overlaid and stretched at the right location. – naktinis Mar 9 '16 at 10:17
  • Did you solve this, and if so, how? – Helen Oct 31 '17 at 19:05

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