Hi Ingmar, that fSpy add-on is very nice. I first saw it in Louis du Mont’s https://cgcookie.com/tutorial/capturing-a-simple-environment-map-for-compositing-cg-elements and that got me interested in trying it out for this project as well.
My results were similar to yours. Although, the focal length value came out to 31.14 mm in my experiment. I have only started the block-out phase, but the cubes seem to be lining up very nicely.
I like how you were able to set the height/scale of the doorway in fSpy. I will have to try that next.
