Full Version: XNurbs for MoI

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It's really nice to see some new surfacing tools, either x-nurbs plugin or implementing ACIS kernel into network and n-sided commands to add more features to them.
While it is not completely related to the x-nurbs discussion, I was thinking, Is it possible to make a plugin to connect moi to freecad library to use its surface filling tool inside moi?

I know it's not as powerful as x-nurbs, But, It has these features:
Making a surface with boundary curves/edges
Accepting guide curves/points
G1/G2 continuity

https://wiki.freecad.org/Surface_Filling

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Hi Mo, that could be a possibility but I haven't heard much about how well it behaves.

Have you used this function in FreeCAD very much?

- Michael

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Hi Michael
Actually, I haven't used it that much except for a couple simple surfaces. But here is a test for more complex situations.
To be fair, I tried to use these videos as reference to compare freecad and x-nurbs results. ( I just quickly glanced at the curves in the videos, so it's not exactly the same. )
https://www.youtube.com/watch?v=mGbYDIqt_MM
https://www.youtube.com/watch?v=a1Himxz1C-Q

As already known, using freecad's surface filling tool was challenging. You can't just select all the boundaries at once and get the x-nurbs magical results.
I tried to minimize the patch area to make it simpler for freecad. You can see the results in the attached file.

Results are not perfect for sure and I totally understand if you don't want to put your time on it. :)

Attachments:
Freecad_surfaceFillingTool.zip

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Hi Mo, thanks for the tests of the Freecad surface filling module.

But yeah it does not look promising, it looks like it is afflicted by oscillations which is often a complication with this type of surface fitting calculation.

You can see them particularly in this surface:







The control points kind of wildly spike back and forth to opposite sides of the surface in a small area. This makes the surface have a kind of subtle bumpy shaping to it in those spots.

Some of the other surfaces in there are not so bad as this one but it does not really bode well for being very reliable.

There are kind of opposing forces between maintaining surface smoothness versus accuracy of forcing the surface to pass through curves. It is quite tricky to balance between these.

There will often be either oscillations or inaccurate results that aren't close enough to join up with the existing edges. Or both.

- Michael

Image Attachments:
freecad_filling1.png  freecad_filling2.png  freecad_filling3.png 

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If so, make cars will be more easy here.
You could recover all users that migrate to Plasticity because of Xnurbs.

M

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