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PRP  
#1 Posted : Tuesday, September 04, 2018 4:45:50 PM(UTC)
PRP

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Joined: 2/28/2009(UTC)
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Man
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Hello Tim,

I have cases where a Skin Surface operation over multiple profiles (meant to be exact cross-sections of the generated surface) are approximate but the surface skips over particularly steep portions of the profiles.

None of the choices in the Options popup seem to help the precision of the surface in following the profiles.

Is there a parameter in the calculations for generating the surface that could be accessed (say in Options) to increase the precision of the calculations? I'd expect a penalty in the calculation time, but in many cases that would be acceptable. One (say default setting) could be used for coarse calculations, then a higher precision set if necessary.

I use the surfaces to generate 3D printed prototypes, and the solids of course include the discrepancies in the surfaces.

In the image, all the curves are continuous, where they seem to have breaks is where the surface isn't tracking closely and covers over the profile. Likewise there are places where the surface is underneath a part of the profile so it's not obvious in the image.


This occurs in all recent versions of ViaCad including Pro 11.

Thanks,

Paul
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Tim Olson  
#2 Posted : Tuesday, September 04, 2018 8:10:49 PM(UTC)
Tim Olson

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Joined: 2/2/2007(UTC)
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Hello Paul

Is it possible that what you are seeing is display resolution? The actual Skin NURB (math definition) is displayed to the user via approximate facets (surface) and line segments (curves). STL uses the triangular facets so it is an issue to be concerned about.

Can you change the resolution to Edit : Change Resolution: Super Fine: Precise and see if that makes a difference?

Tim

Tim Olson
ViaCAD/Shark Development Team
Links to ViaCAD Resources
PRP  
#3 Posted : Wednesday, September 05, 2018 8:02:27 AM(UTC)
PRP

Rank: Senior Member

Joined: 2/28/2009(UTC)
Posts: 129
Man
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Tim,

Bingo!

Funny, I almost always set the profiles to Superfine and then the surface to superfine also. The case shown had superfine profiles but not the surface. Below is image with all superfine.

That seems to solve it, see image.

Regarding 3D printing, I always take the stl defaults and adjust Normal Deviation lower and lower until I reach close to the Shapeways limit in number of triangles (<1,000,000), then check to insure the file size is below their limit of 64MB.
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