Hi,

I have a Maya to Houdini workflow that I am trying to figure out. I have a number of objects with pivots placed in a specific place in Maya. I export these to Houdini as either Alembic or FBX, run a RBD simulation and then export the results.

I want to export the results back to Maya, with pivots and object names intact.For now, I am just exporting the final frame, and using the RBD to create a pile of objects, but it would also be great to export objects with transform animation from the RBD sim.

Thank you,

Adnan Hussain

Have you tried the using the “Build Hierarchy from Path Attribute” feature on the ROP RBX node? That should export the animated pieces to FBX. I don't know if you can preserve the same pivots though.

Thanks for the reply Edward. Ok, I am still working this out, but I made some progress, including using your tip.

I can confirm that the pivots come in correct when I use fbxcharacterimport and just grab the rest pose.

However, I have tried each fbx export method and failed. 2 methods, character and anim out give the missing 'name' point attribute in animated pose error and rop_fbx never gets the pivot correct, after trying every combination of options on that node that I could think of.

I feel I am close, but not quite there. The names export correctly thanks to Build Hierarchy from Path Attribute when I use name as the path attribute in rop_fbx, but the pivots are incorrect.

Thanks,

Adnan Hussain

Not following. There are specific required attributes when using the KineFX FBX exporters (ie. ROP FBX Animation Output and ROP FBX Character Output), that the old ROP FBX Output node does not require. So what I'd expect is that you can only use the KineFX ones to re-export FBX files that you imported with FBX Character Import. For the initial RBD sim export, use ROP FBX Output.

Thanks Edward,

yes, that makes sense. My point is just that I am trying everything that I can think of to get the pivots out correctly. ROP FBX Export has the most options and is what I need, but I have not been able to get it to keep the pivots as they were, or export transform animation.

Ok, so the best results I was able to get were with the setup seen in the image below. No checkboxes checked in the rop_fbx fbx settings. This setup gives me transform animation on each object, with correct naming. The scale of these boxes was set to 10 in the source fbx, so that was lost along with the original pivot locations, but other than that it looks good.

So, I can take this into Maya, and parent constraint the source objects with correct pivots to the ones (using a python script) with incorrect ones and rbd sim from Houdini and bake them out to get what I need in this instance.

That's as far as I could get with this process. If anyone has a better way, I'd love to hear it, but this will get me by for now.

Thank you,

Adnan Hussain