Perspective tool changes aspect ratio in darktable

[paulmiller]

This has come up before, there is a discussion here:

Perspective Correction does not respect proportion

Hello, I am an architect, and proportion is a very important issue in facades. When I use the wonderful Perspective Correction module combined with the Lens Correction module, I get truly orthogonal results. The problem is that these are out of proportion. A square window becomes a rectangle. [10006941975_b57b156896_o] [10006941975_b57b156896_o_dt_pc] Is this possible to achieve using the implemented features? Or would that need extra dev work? (other softwares which can achieve the square …

The answer appears to be to select Lens Model = Specific in the perspective module:

Perspective Correction does not respect proportion

Use the “lens model” → “specific” option in dt module, instead of “generic” [Capture%20d%E2%80%99%C3%A9cran%20de%202019-05-22%2017-52-53]