Subd to nurbs is incorrect or unclean

subd to nurbs is incorrect or unclean. on almost all of my components.
when i trim, there are often problems with the structure of the polygon areas.

Problems look like this:
torn edges, wavy surfaces, sometimes broken surface elements.

Is that normal with subd to nurbs? is rhino7 still faulty or am I doing something wrong?

I built half of my master’s thesis in subd and have many problems with the converted subd to nurbs surfaces. looks like shit and causes problems.
actually to be thrown away, months of work.

In the file is a subd model at the bottom and the nurbs at the top. in the example the corners are unclean. over there should be a window later, but the frame now touches the window (after converting to nurbs) → rendering is then ugly.

why does converting from subd to nurbs not clean?

regards

nik

Subd to Nurbs Bugs.3dm (10.0 MB)

Hi @nik.mvk
I think what you are seeing is just the render mesh being to loose. Try setting it to custom and leave everything at 0 except for Density=1 and Max Distance, Edge to Surf=0.25 - that should give you a precise NURBS representation. In general, I think modeling something that is ~32 meters long shouldn’t use an absolute tolerance of 0.001mm - that’s almost asking for trouble.
HTH, Jakob

1 Like

Hi, Some of your sud’s are folding back on themselves . I am not making excuses for the software , but those sharp edges on your subd model would never be built in the real world.—Mark

@Normand

Thank you. I am reassured now.surface looks good now. I thought the parts are all bad.
but with all parts in my rhino file the pc struggle a little bit.
to work i just leave the old seetings to work, then the pc runs better with the file.

thank very much. :slightly_smiling_face: