Hi Colin, well here you're running into an issue that's more than just translating between different file containers, you're also trying to translate between very different data types.

The data that is generated from 3D-Coat and saved into OBJ format is polygon mesh type data, where there are not any curved spline surfaces in the data, instead the data is made up of a whole lot of little tiny flat polygon facets.

IGES format on the other hand, is meant to contain smooth NURBS surface data, where surfaces that look like they are smooth are actually made up of larger spline patches instead of a whole lot of little flat facets.

MoI is only designed to work on that kind of NURBS surface data and is not set up to work on polygon mesh data. So it's not really feasible to export from 3D-Coat into MoI, you are using a much different kind of data there in 3D-Coat than what MoI uses.

It's kind of like saying you want to make a graphic in Photoshop and then bring that into Microsoft Word to spell check it, or something like that.


There are some tools you could use to try and recalculate the data into NURBS form, but that can be a tricky reverse engineering process.

If you have a relatively small number of facets, you could use the MeshToNurb command in Rhino to convert each facet into a trimmed NURBS plane. But be aware that this behaves poorly for converting a very dense mesh, as NURBS are designed to have smooth surfaces as larger spline surfaces and not as a zillion little fragments.

If you have something that is supposed to be used as the control hull for a subdivision surface, then you could try using the T-splines plugin for Rhino to convert it to a smoothed NURBS result.

Otherwise, you could try some of the fancy and expensive reverse engineering solutions that fit NURBS surfaces to polygon mesh data, check out this previous post for some links to that:
http://moi3d.com/forum/index.php?webtag=MOI&msg=2469.3


Also see here for some previous discussion:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3332.9

 

It works much easier to start with NURBS and then export to polygons - that would be like starting in MoI and then exporting into 3D-Coat, instead of the other way around like you are trying to do here.

That's because MoI can generate polygon data from NURBS data by producing all those little facets. But starting with a ton of facets it is hard to go back the other direction. It's kind of like how you can take apples and smash them up into applesauce, but if you start with applesauce it is pretty difficult to make apples from it.

So for the most part that opposite direction of starting in 3D-Coat and then trying to go into MoI from there is not really feasible.

- Michael