Full Version: Importing to Moi3d

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Hi Raven, it sounds like probably the model is made with polygon mesh data, not with CAD surface data.

.3dm files from Rhino can contain different kinds of objects in them, MOI will only read the CAD solids and surfaces and not polygon mesh objects.

.obj, .stl, and .fbx are all going to have polygon mesh objects in them. So something that looks like a sphere is made up of a whole bunch of little triangles and not a single sphere surface like it is in CAD data.

It is difficult to convert that kind of faceted data into structured CAD form. The ImportOBJ and STLImport scripts try to do it in a kind of hacky way by making a trimmed plane surface for every triangle in the polygon mesh. CAD programs are not designed to work on that kind of data, it becomes very heavy and unwieldy.

So it's likely that the model is made up of a pretty dense polygon mesh and that data is not suitable to be loaded into MOI. You would probably need to work with it in a polygon modeling program, not in MOI which does not do poly modeling.

That's why .obj and .stl import are not part of the built in MOI importers.

- Michael

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Thanks for that Michael - yes I kinda suspected that.
Can you suggest some means of converting said file(s) into even a low res version that Moi could use?

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If your object is less than 10 000 polys you can try
the _importObj by Max Smirnov http://moi3d.com/wiki/MaxScriptArchive
But you must convert first your "3dm" file --->OBJ!

or the native SubD / Create ;)

For decimate OBJ itself : Zbrush has a terrific one : Decimation Master

Maybe the free online OnShape can also make that! ;)
https://www.onshape.com

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Hi Raven,

re:
> Can you suggest some means of converting said file(s) into even a low res version that Moi could use?

There is a process called "reverse engineering" (https://wiki.mcneel.com/rhino/reverseengineering) but it's a very difficult process using special and expensive tools to create larger spline patches over top of a dense polygon mesh.

Or also like Pilou writes above most polygon modeling programs have a poly reduction tool. I think there's a free one in MeshMixer you could try:
https://meshmixer.com/
https://www.youtube.com/watch?v=921cDYBpuL4

But in general it's kind of a square peg round hole type thing. It's usually not suitable to work with that type of polygon data in MOI.

You can export CAD models out to a polygon mesh which will dice up the model but going the other direction is difficult.

- Michael

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