Deborah R. Fowler
Houdini with
Mocap
Posted on April 11 2016Updated on Feb 5 2017
Refer also to the Houdini Documentation http://www.sidefx.com/docs/houdini15.0/character/motioncapture
Using fbx motion capture data out of Vicon Blade or from Motion
Builder is easy. Import the fbx. Be aware that Houdini does
exactly as you tell it. You need to set the fps on your import to
override your data - if you do not, it will come in as 120
fps. You can use merge or import (import will override what
is there, merge will add the fbx to your existing contents). The
examples are show for an fbx from Blade. (If you were to do an fbx
that had Geometry/Materials or Cameras you would change the Filter
Options).
For speed, you can change the option from Every 1 frames to say
8, but be sure to override the FPS.
(NOTE THIS WOULD BE FOR PREVIS - if you need accurate data use
every 1 frame.
TIP: Cleaning up your fbx in Mobu before bringing it in to Houdini will also speed up the fbx load, ie. system, unlabeled markers etc.
TIP: If for some reason you create an abc to go from
Houdini to Maya with this data - don't. Okay, go ahead but be
careful since fbx data is not designed to be renderable usually
you will have to create the alembic, click off visibility and
then create another alembic container.
For your first exercise, to add geometry to the skeleton you can using parenting with the skeleton parts.
Alternatively you can put them inside the nodes - you will then have to make the node renderable (it is off by default). Simply
- lasso select the node tree
- select the misc tab
- deselect the root/spine (hold shift, and de-select (top level solving/solving_hips/solving_spine) ie. until you see renderable appear)
- click renderable.
If you forget to change the Override FBX
Frame Rate, your data will come in at 120 fps (Maya converts it
automatically, Houdini trusts you to change it). You can change it
in the Global Animation Settings.
However, be aware that this works correctly if you are using Every 1 frame. If you use the Override FBX Frame Rate you can use a higher frame rate and still get accurate data, however if you use say 8 and change it after the fact in the Global Animation Options it will result in a different interpretation of data as seen in the cartwheel example below.
Image: on the left in Maya, compared on the right in Houdini
- 1) with frame 1 and overridden fps on import
- 2) with frame every 1, not overridden and changed in animation options
- 3) with frame 8 and overridden fps on import
Below
- compared to frame 8 and not overridden and changed in the animation options
