[GRASS-user] Reverse i.rectify

[Dwight Needels]

I have a historic map that I georeferenced using i.rectify. To help me
compare features to modern maps, I have overlaid a 1¹ lon/lat grid.

I would like to display the undistorted original XY map with the lon/lat
grid back-projected on top to show the geometric distortion. In other words,
I want the originally straight lines of the grid displayed as curves based
on the reverse of the i.rectify transformation.

Is there any way to extract the transform parameters and use them to reverse
the i.rectify transformation? Are there other ways to accomplish something
similar?

Thanks,

-Dwight
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