Hi all, I'm new to these operators, but it looks like when blend shape or "morphing" is required, the source of the deformed mesh should be processed outside Houdini (in a sculpt software) because KineFX does not have a built-in tool for crazy morphing. So things like facial expression morphing should be created in another software.

And it is contradict to the traditional obj level rigging's blend shape. In this H17 feature video, they shows a blend shape with built-in surface editing. This is not the KineFX pipeline right?

Bone deformation and blendshapes happen in sop context in the traditional and kinefx workflow, so I don't see why you couldn't use houdini's editing and sculpting tools to create blendshapes.
You can even create a facial rig and use the output as blendshapes (cached if you want good performance).

forton
Bone deformation and blendshapes happen in sop context in the traditional and kinefx workflow, so I don't see why you couldn't use houdini's editing and sculpting tools to create blendshapes.
You can even create a facial rig and use the output as blendshapes (cached if you want good performance).

Hi Forton, thanks for the reply. I'm trying to move a group of face vertices. I think in Houdini's sculpt tool only normal displacement function is available.
I export the mesh to Zbrush and use the "move" brush to configure the face.
But when I export it back to Houdini, and use a blend shape, it causes error.

So I tried with the blendshape sop first, and then it breaks..



I think it might be the index of the points has been messed up.
Because when I try to export it to Zbrush, Zbrush reports error and did not convert polys of different materials to different subtools.But I think that blend is only about pushing/pulling points to new positions; and even if we have a in-correct index pairs, and mis-match attributes, that will not affect Houdini's process of pushing/pulling points.

But looks like I'm wrong.

https://www.sidefx.com/docs/houdini/character/kinefx/blendshapes.html [www.sidefx.com]
And I went back to this help document, that just says we do not have a tool for the sculpting, and there are no tutorials on laying down the nodes.

This is the minimum system or the current error.



In short, I cannot find a pipeline to pull a part of the surface, and the current trial in external programs will cause a lost of attributes which causes a faulty blend shape.

You could try to match the existing topology to the newly sculpted one using this tool:

https://www.sidefx.com/docs/houdini/nodes/sop/topotransfer.html [www.sidefx.com]

protozoan
You could try to match the existing topology to the newly sculpted one using this tool:

https://www.sidefx.com/docs/houdini/nodes/sop/topotransfer.html [www.sidefx.com]

Hi Protozoan, thanks for the suggestion I'm looking at it now.

I think it is that wrong point index and missing attribute will cause problems.
If I sculp on the node after the FBXCharimport node, which will not affect attributes other than P and N, the blend shape works
.
The correct title of the thread should be "Is there a pipeline document on using external sculpting tool to prepare for blend shapes without losing attributes in the process"
Well the site don't allow me to type such a long title:/

If you have exactly the same topology but just reordered points, https://www.sidefx.com/docs/houdini/nodes/sop/matchtopology.html [www.sidefx.com] may help to reorder the points on the externally sculpted shape. But yeah, Topo Transfer should also work but it's a more expensive algorithm but without the exact same topology requirement.