I have some low-quality vector data and I'm trying to align some higher-quality raster images with it so that I can improve the vectors. Unfortunately the rasters have no control points or coordinates, so I have to align the images by matching up two identifiable points that exist in both the raster and the vector:

Raster at left, vector at right, with corresponding points identified

In my 3D software, I can align to these two points without distortion simply by locking the aspect ratio, to get this result:

Desired alignment

But using the Qgis Georeferencer with the same points, I get a distorted result (note that the raster is now considerably less wide left-to-right than the vector):

Distorted output from Georeferencer

I tried different transformation types in the georeferencer and none of them gave the desired result. I kept the CRS set to the same one as the project (WGS84).

How can I align the raster in QGIS with a simple rotate and scale, without altering the aspect ratio?

1 Answer 1


Problem resolved. As it turns out there were a couple different things going on:

  • The rasters seem to be projected with a different CRS than my project. I set the project CRS to the appropriate UTM zone and found that the vector distortion was less pronounced, allowing for a better alignment.
  • Additionally, the raster I was working from was just not very good, as I found when I started trying to align it with satellite imagery.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.