After importing a client’s type 186 IGES file into MoI, a weird extra surface shows up. In the snapshot below it is the large “ring” surface that I’ve selected. Looks like it was used to make a surface on the grid pattern of the object.




Here is a closeup. The surface is weird because there are no selectable edges on those yellow rectangles.



Does anyone know what is going on here? The original model was created in SolidWorks. Is this ring surface something that MoI can’t translate? Thanks for any help you can provide!

– Randy

Hi Randy - that could be either just a display problem where the display mesher is not working right on that particular surface, or it could be a problem in the trimming information of that surface (like the edges are garbled somehow) which then makes a bad display mesh as a result of a messed up trimming boundary.

I'd need to examine the model to know exactly what is going on - is it possible for you to post the IGES file or e-mail it to me at moi@moi3d.com if you want to keep it private?

You might also try exporting from SolidWorks using IGES type 144 individual surfaces instead of as IGES type 186. I think it's possible that the type 186 only contains 3D trimming information and that makes MoI need to do some additional calculations for bringing those 3D curves down into the UV parameter space of each surface during the import, and that's a fairly complex process that can potentially go wrong. If I remember right, the type 144 IGES entities contain the UV parameter space curves in the IGES data so that could avoid some bug or difficult-to-process situation that is making the current problem.

Also if the rest of the model imported fine and the problem is just that 1 surface that has a messed up trimming boundary, it should be possible to repair the surface by untrimming it and then re-trimming it. I can do that for you if you can send me the model.

- Michael