For context: I need to convert a STEP file into a polygon model to import into blender. From what I can tell, the best free solution would be to export the Model from FreeCAD. The problem I’ve been having is that the tesselation is angle-based and this specific model has a curved surface that would need a very high poly count to make it sufficiently smooth and the polygon distribution is extremely inefficient, because some areas have way too many polygons while others have too few.
So my questions are:
Is there maybe a better way to control the tesselation of the mesh in FreeCAD?
Are there other free or cheap solutions that may be better for this?
Is there anything I can do to the CAD model to make the tesselation better? The angle-based tesselation seems problematic for my model. (I know virtually nothing about CAD modeling).
Is there another method for getting a CAD model into blender or is remodeling it the only way to get better geometry? (To be clear, I don’t need perfect topology, it can be triangulated, as long as the surfaces look good, the shape is accurate and the polycount is manageable)
This depends totally on the used topology and what “looks” good means for you… for example some cylinders “crossing each other” might look even good if not using any booleans at all but simply rendering them while the origianl CAD data was meant to “produce” them.
For example on Polycount…
there are lots of “solutions” which does look good in games and even product presentational videos when a CAD’ler might go crazy on the used topology…
I don’t need good looking topology (in the sense of clean topology), I just need it to be shaded correctly. Here are some images to better illustrate the problem:
These are three versions of the same model at different tessellation factors. You can see how uneven the geometry distribution is. Although now I think the problem may actually be with the CAD data and not the tessellation method? I’m not sure and I don’t know how to check tbh.
@RobWu Do you know wether the Step importer addon tesselates meshes differently? In case you are familiar with the addon, do you know wether this is something that might work better with the addon?
What you’re seeing in inherent of getting CAD/curve based objects into a 3D application. Sometimes you don’t get it working properly and need to rebuild parts of the polygon geometry.
And no, I don’t have any experience with the addon. You might contact the creator of the addon to see if he can answer some question on this.
The step importer addon works pretty decently a lot of times. Sometimes it does not work, skips objects or imports them as weird blown up bubbles.
Anyway, one nice thing about the step addon is that after you import you can select specific obects and reimport these selected objects with less or higher tesselation.
Could be an issue with Custom Split Normal Data. For example when importing with STEPper add-on the model has an applied Custom Split Normal Data. Which could be fine for some things and not others. You could check if that’s there, clear it, and re-smooth to see if that helps.
But as has been stated, sometimes going from NURBS to polys does weird and unexpected things.
