How to keep file hierarchy when exporting from Rhino?

We are evaluating Rhino for converting CAD step files to fbx for import into Maya.

We are very happy with the quality of the polygon tesselation of the converted NURBS surfaces and quality of surface normals, but so far we have been unable to maintain the file hierarchy when exporting from Rhino.

We get a file with full hierarchial organisation when using MODO for converting step to fbx, but the quality of the geomety is bad compared to Rhino, so we much prefer to use Rhino, but really, really need the hierarchy.

I have explored options using the blocks in the file, but so far without achieving any kind of hierarchial organisation.

How can I do this with Rhino?

Best Regards
Morten - HTZ

Hi Morten - what hierarchy are you referring to? Is it the block hierarchy that comes with the step file you are converting?


Hi Pascal,

Thank you for a quick reply.

The STEP files we receive from our client are created in Solidworks. When we open them with Modo and export as FBX, then import to Maya, we have full logical hierarchy, which we can inspect in Modo as well as Maya.
The hierarchy is a logical scene organisation where all parts for logical collections of objects are gathered under a parent node, in structural parts. An example would be all parts of a wheel, door, lid or similar, which need to be able to move or rotate together. Naming is kept from the STEP file to Maya which is sometimes helpful if the CAD modeler has been a bit organised.

This hierarchy appears to be interpreted as blocks in Rhino. Blocks seem to have no hierarchial informatoin, but only provide some from of grouping of objects
I have tried exporting from Rhino exploded blocks as well as non exploded blocks,but when I import the FBX from Rhino in Maya the hierarchy is gone, and every part is in a flat hierarchy under one parent node.
Obviously this creates a lot of tedious work reorganising parts in new groups in Maya before the model is useful for our purposes.

The reason we are evaluating Rhino is because Modo produces inferior tesselation of the STEP files, resulting in bad shading and a lot of manual clean up work. The polygonal surfaces from Rhino look a lot better. Rhino also retains the correct scaling of the items, which is important, and Modo apparently does not.
So we would really like to use Rhino, provided we can keep the hierarchial information in the scene.

I have attached screenshots of the hierarchial tree in Modo and Maya as well as the Block Manager in Rhino. They are displaying the contents of the same STEP file.

I am hoping Rhino is capable of keeping this kind of information so we can make good use of it :slight_smile:

Best regards

Hello - so, if I understand, FBX export supporting Rhino blocks might be the thing that would help, correct?


Hi Pascal,

Blocks might be helpful, but it depends on what they actually support.

The important thing is to support the full hierarchy tree structure as it comes from Solidworks. It is an invaluable tool when handling complex models.

  • Morten

Hi Morten - well, Rhino does not have any such hierarchy. Blocks or layers are are what we have - it is possible the block structure can be supported in fbx export, I really do not know, but that seems like the best bet; otherwise, maybe you can pester Maya to support opening Solidworks files…

The item we have open for fbx instance support is aspparently not an easy thing to fix:
RH-57258 Figure out instance reference/definitions for FBX I/O


Bummer - Hierarchy is all important in this kind of work. It is indispensable as it is instrumental in organising complex objects.

It will however be helpful if we can get blocks as a sort of groups or siimilar in Maya. Is that possible?

  • Morten