Hi Martin - the problem is that Keyshot only reads render mesh data from the 3DM files, it does not try to process the NURBS objects directly.
That means that it will not work with 3DM files saved from MoI - MoI will only ever store plain NURBS objects in the 3DM file, unlike Rhino. Rhino tends to be pretty slow when calculating its render meshes for doing a shaded display, so when it finishes calculating them it will store them as extra data in the 3DM file basically attached to the NURBS objects. That's just a kind of data caching mechanism used by Rhino but a few render programs will only look at that render mesh data only and not try to deal with the actual NURBS objects themselves.
MoI does not try to store any additional render mesh data in the 3DM file - it doesn't have to since MoI has a very quick display mesh calculation compared to Rhino and the display meshes can tend to bloat up the file size by quite a bit so it's not great to store them in the file if it is not necessary.
If you are in Rhino and do a shaded view (instead of leaving a wireframe view only), it then calculates render meshes at that point and that will have a side effect of storing that render mesh data in the 3DM file (unless you do a "Save small" from Rhino - that's another reason why it's not so great to depend on this particular piece of data since Rhino does not necessarily write it all the time either itself). So that's what that nag about shading in Rhino is about. But none of that applies to MoI, MoI will never store cached render mesh display data in the 3DM file no matter what kind of display you do in MoI. That's actually a nice feature of MoI that it does not need to bloat up the files with that extra cached display data in them.
So anyway, you might want to contact KeyShot support, and ask them to do a more thorough job of supporting the 3DM format and to actually read and process the real NURBS objects inside the file like they do for other CAD formats like IGES and STEP, rather than only trying to do this Rhino display data cache type shortcut.
Until then you can still use MoI in combination with KeyShot, it's just 3DM format that won't work. Instead I'd recommend using OBJ format for transfer from MoI into KeyShot - in the MoI mesh options that pop up set the option for "Output: Quads & Triangles" instead of the default "Output: N-gons" because I don't think KeyShot likes to handle complex n-gon polygons (polygons with more than just 3 or 4 sides). But if you set "Output: Quads & Triangles" it should transfer to KeyShot just fine.
And actually even if 3DM NURBS were fully supported by KeyShot I'd actually still recommend using OBJ format anyway, since when you do that you end up using MoI's mesher to produce the polygons and MoI actually has a particularly nice mesh generation mechanism.
So it's probably not particularly any great loss to not have the 3DM NURBS import working anyway, you are most likely better off using OBJ format which is the main method that you would want to use for transfer right now anyway.
3DM NURBS format transfer is more valuable for programs that are more focused on dealing with the NURBS models directly like another CAD program, not so much for rendering programs. The first thing that rendering programs do when reading NURBS data is to convert it to polygons and then usually throw away the NURBS data anyway since they are usually only focused on dealing with polygon data. So if you're targeting export to a rendering program, exporting polygon data from MoI is a better fit for that type of thing anyway.
Hope this helps explain what you were seeing.
- Michael
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