How to separate a polysurface?

[Anonymous]

I've imported an FBX file into Maya. The model had a skin and skeleton with animation. The skeleton (joints and bones) was imported with a detailed hierarchy. However, the surface was imported as one polysurface which I could separate into 2. When I view the hypergraph hierarchy for one polysurface it shows only 1 entry.

Looking at the wireframe of the model it's obvious it's constructed from many polygons. I tried using Separate but got an error that the "polysurface has one piece". Here is only one of the 2 polysurfaces

How can I "create" a hierarchy or have it imported correctly. The result should be a .ma file. In practice, I need to select some of the polygons on the surface and group them. I attached the file.

[Anonymous]

Look like Edit Mesh > Extract does something like what I'm looking for, but I'm still getting different behavior for the extracted and original meshes.

[trevor.adams]

Hi @Anonymous,

The 'Separate' operation in Maya is intended to separate geometric shells from one another (when they're all part of a single object in Maya), resulting in 2 separate objects.  For example, if you create 2 spheres and you combine them using 'Combine', you now have 1 object with 2 geometric shells (2 separate islands of polygons, in other words).  And then if you use 'Separate' while one of those spheres is selected, it will separate both spheres as separate objects once again in Maya.  In short, Separate works on isolated groups of polygons that are part of a single object.

The 'Extract' operation is indeed more along the lines of what you're looking for - to 'extract' selected faces from an object and create them as a separate object in Maya.  For example, if you create a sphere, then select a few faces on it and run 'Separate', you will end up with 2 separate objects - the selected faces, and the original sphere with those faces removed.

Now what can be confusing (and is something I would like to improve on in the future), is the result you get from either operation - it can be a bit of a mess in the Outliner.  So a quick tip would be to simply delete history once you run your Separate or Extract operation; i.e. select faces on a sphere, run 'Extract', hover over the meshes and hold A+LMB and choose 'Delete History' (or choose it from the Edit menu).  You will now have a group node with 2 objects - don't want them in a single group?  Simply Select the group node and select Edit > Ungroup.

Hope that helps!