# Bind Skeleton to Asset
This document outlines the Multiverse workflow to “bind” USD skeleton animation to a USD Asset that contains a (static) skeleton along with mesh and skin weights.
As a result you will write a USD or USDZ composition where the skeleton animation will dive the skeleton.
The final data can be read again in Maya viaMultiverse, or read by other DCC apps or used for preview as USDZ in Apple macOS and iOS.
- Write USD Asset explains how to write static data properly for skinning
- Write USD Composition explains how to write a composition, which you will use for the final step of outputting combined data (staic + anim).
- Write Preview Materials to USD and Write Display Color to USD explains how to setup preview materials and/or display color.
- USDZ output for AR explains how to write output to USDZ.
# Preparing the data
Let’s Start with the Maya setup: a skinned mesh + rig. Make sure that your rig is separate from you geometry, e.g:
/root/ /root/mesh (...) /root/rig (...)
# Write static asset
Then select the root node and Multiverse Write a USD Asset with
joints on and
skin weight on. You are writing a static (non-animated) file, so set the time
settings to current frame:
# Read the data
Either make a new scene or simply hide the Maya asset, then:
Read the USD data you just wrote in the previous step (skinned static mesh + skeleton)
Read the USD data coming from your motion capture application. In this example we are using an animated skeleton data coming from Vicon Shogun.
The skeleton hierarchy in the skinned mesh has to match the animated skeleton hierarchy imported from the mocap application — they must have the same number of joints with the same names and the same structure (same children for each matching joint).
As a result here you basically have two Multiverse compounds in the Maya scene.
# Establish skeleton⇆animation relationship
Group the two compounds together:
/group/ /group/compound1 /group/compound2
Select the Compound with the animated skeleton: open MEOW and find the animated skeleton item, then RMB and click “Use animated skeleton as source”:
Select the Compound with the static asset: open MEOW and find the static skeleton item, then RMB and click “Apply animation source”:
You should now see a glowing icon on MEOW indicating that you have established a relationship.
# Write a composition
Select the group node and perform a Write a USD Composition (because the source data here are Multiverse compounds and groups, not Maya data).
Remember that the composition is animated, so we are using the same frame range length as the Vicon animation (500 frames) in the time settings:
# Read the animated character
Once the data has been written, create a new scene (or hide everything in the current one) and Read the USD/USDZ file you just created to playback in Maya.
Note that if you have written a USDZ file you can see it in the usual Apple ways (macOS quick look, iOS…)
USDZ reading via Apple Quick Look on a Mac Mini (with Intel graphics) does not display the skinned animation, however a proper machine with GPU such as a MBP with Radeon or a Mac Pro will display it.