Hi Jim, even though Maya and Houdini both support NURBS and the IGES format, they are not really very focused on handling it. In practice Maya users for example use OBJ format and polygon data much, much more frequently.

So even though they technically support it, it is an underutilized and less refined area of those programs, and it's probably best not to rely on it.

NURBS data is something that is more strongly supported in CAD programs, and it is not as well supported in animation programs just in general. In various animation programs their NURBS support is old and has not had many resources devoted to fixing it up over the years. They've been much more focused on sub-d modeling for quite a while now.

Maya, Houdini, Softimage, and 3DS Max are all kind of similar in this aspect.

For these particular programs you should get better results if you export polygon data in OBJ format (or FBX for Max) instead of trying to use their native NURBS functionality. For Modo or LightWave use LWO format.

- Michael