I’ve previously tried a form of camera projection modelling/texturing by using fspy to match a camera to a photo, then model against the  camera view and texturing by using Project from View to UV unwrap the object and apply the photo as an image texture. Works pretty well. However I’ve just found a tutorial on CGCookie that shows how to do proper camera projection using the UVproject modifier, which is pretty much the same kind of process as in Garrett Fry’s Gnomon tutorial that I first got inspired by.

Previously I set the image as a background to the camera and modelled against the image. However it is possible to texture the geo with the image by using it as an image texture and using Window as the vector source in the Texture Coordinate node. Later change this to UV once the model is finished. And don’t forget to set the correct x/y ratio in the uvproject modifiet.

I might go back to Garrett Fry’s original tutorial and try it again. It included some photogrammetry, which I’ve done for my scene, and it would be good to finish it off properly. I found it a very inspiring tutorial.