I made it and sections seems very good. No crashes on surfaces, daylights comes fine with project's ground surface. If the problems is shaded views, why I get the shaded view result in my rendering? I tried to make some changes in 3dconfig, but everything what I could get from that was not only crash of surface, but also of definition sections... BUT rendering seemed the same as it was... It seems that contours (edges) for triangle surface are drawn all right, but the surface doesn't follow them the way he should.