Hi SideFX peeps.

IS USD animation curves somthing that might be looked at in the future?

Best. Mark

what do you mean by this vague question?

USD animation curves or splines are part of usd core since 25.08 so I assume they will automatically be supported for Houdini versions using USD 25.08

if you mean if there will be support for import/export between sop Channel Primitives and USD animation splines, I'm sure that will come, and I personally hope for more robust Channel Primitives as well as more robust usd animation splines

since currently they both seem to neglect quaternion channels, or float3 rotation channels marked as quaternion, which is very common in many DCCs, so I was surprised to read this:

https://github.com/PixarAnimationStudios/OpenUSD-proposals/tree/main/proposals/spline-animation
...quaternions aren't typically authored with user-controlled tangents. We believe the only broadly useful interpolation behavior for quaternions is slerp, which time samples already provide.

which I don't believe is true and also pure slerp is useless for smooth animation interpolation as it's discontinuous at keys/timesamples
I have successfully used TCB and TCBS quaternion interpolation types in the past in MAX and XSI which provide a lot of control and can produce both continuous and discontinuous quaternion interpolation and are quite standard in many DCCs

Hi. Thanks for the very detailed response. !

Mark