Thanks jeff for your efforts. I know there is lots of layers, and also I tried moving everything to a Layer0 which is sketchup default layer I believe but nothing changed in that model that you tried. Well I realize something I'm not sure about it but, SU automatically smooths some edges I think? I mean each Height Level (contours) was COMPONENT when I imported from autocad anyway, yesterday I exploded them to make it GROUP to get rid of components, and to make it just single geometry. Maybe that causes such behaviour like this.. Now I think, SU changes or soften some edges in every "make component/explode" situation in bigger geometries, models. [image: ss4.png] This is the model that Im talking about. I didnt tried on this before, shame for me If you still interesting you may check this model with unexploded height contours components. Looks like problem solved spontaneously for me . fyi, this 2nd model that I upload have much more edges than other. Thanks for your time.