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Rendering Advantage for NURBS or Solids or Generic Solids?


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I am in the process of importing some 3D models of relatively complicated collections of NURBS surfaces. These models are going to take a fair amount of cleanup. Obviously, since these are surfaces (imported via IGES/STEP/DWG), the objects are hollow.

 

If I have to clean these up anyway, are there advantages in render times if I:

 

1. Leave them as groups/symbols with hundreds of individual NURBS surfaces?

2. Clean them up and compose them into a smaller (or even one) NURBS surface?

3. Clean them up and make Solids out of them?

4. Clean them up and make a single Generic Solid?

 

Experience or opinions appreciated.

 

 

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  • Vectorworks, Inc Employee

@Pat Stanford A generic solid is just a bag of surfaces, as far as the rendering is concerned.  The only advantage I can think of right now might be trimming of the surfaces that might happen when converted.  Combining several into one could save some triangles, but this depends on what your geometry is here.  A bit flat plane made of hundreds of separate flat NURBs surface tiles would be better as a single flat plane.  Two spheroid shapes being combined into the same geometry but as one generic solid won't save much I think.  If several are combined into one the detail setting of the renderer might be spread out over the whole object, which might reduce the total triangles, in trade for maybe chunkier results compared to when they were separate surfaces.

 

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Something like in this picture.  2669 NURBS Surfaces.  To get the texturing I need I could reduce that down to about 10 objects + replace all the fasteners with symbols.

 

Note that you can see at the bottom front foot of the blue body that there is a missing surface. Many more missing on the underside.

 

If I don't simplify the shapes, what would my best options be to improve rendering?  Full drawing will probably have about 10 object similar to this (but probably simpler) along with hundreds of VW native objects. Dimensions are about 2.5'x2'x1'.  Overall combined object will be about 8'x20'x8'

 

 

image.thumb.png.072cdf702978febd402ac33aee75b879.png

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  • Vectorworks, Inc Employee

If this is just for presentation/rendering purposes I would be tempted to convert to mesh and then use Modify->Simplify Mesh on the parts.  And yes anything not visible can be removed if those internals are irrelevant to the visuals.

 

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  • Vectorworks, Inc Employee
14 hours ago, Pat Stanford said:

There is a hole under each of the fasteners. Would covering those holes help?  Or for the planar surfaces (the bars at the front and top) rebuilding them as a single surface without the holes?

 

If it's not going to visible then it's unnecessary.  Also you could think about it by sizes, an automatic simplification would remove small things first.  Even better small complex things first.

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