Hans,

I have now a case where I see an artefact in Q3 and Q4 but not Q1 and Q2:

http://netcup.bokomoko.de/~rd/sweethome3D/sh3d-artefact5.png

I would have expected the outer wall to be flat, but it seems to have a strange step on the right half.

The rendering is taken with Q4 on the same sh3d file as before.

Do you have any idea what goes wrong?

Thanks
Rainer

PS: I am downloading 4.6 to install it on the side.