Thanks for the replies. I worked out what the issue was in the end. The camera was coming through in the right position and focal length. However, when I changed the size of the render window to match the photograph the focal length of the camera changed. So after fixing the size of the render I went back and changed the focal length back to the original value and it worked perfectly. Thanks again for your replies. Andy

My one-liner posted earlier will 'zero' all selected objects so that their bounds.min.z=0... It will 'destroy' some selected objects like vertical faces, when their edges all get to be 'coincident' on the ground!! Hence the warning about it being best used on groups/component-instances...

Have you already seen this thread? http://forums.sketchucation.com/viewtopic.php?p=360003#p360003 Read TIG's and Didier's posts, maybe it's useful.

Also look for my TextureTools which allow you to Rotate/Scale/Position any texture on a selected face either by typing in an amount OR by using the arrow keys... Search the Plugins Index...

Also instead of going all around, you can halve the whole shape by connecting opposite endpoints that halve the remaining offending face etc. until you quickly isolate the problematic area. Then just delete the unnecessary edges inside.

I don't think that repair_broken_lines.rb will close gaps. It looks like it just replaces collinear connected edges with a single edge. Sounds like an interesting problem. I'm surprised that there isn't a free script to solve it.