RBD retime rotation problem

[Polyxion]

Hi everyone,

 

I´m fairly new to houdini and this forum already did a fantastic job answering my questions just by reading through all of these posts. But now I got a little stuck and haven´t really found a clear explanation for my problem.
I have done a RBD Simulation, which is prefractured, simulated in DOPs and cached out as bgeo. Afterwards I created a time blend and time shift node to retime the simulation (not linear, maximum is about four times slower). The slowdown of the translation data is fine, but the rotation has some strange jumping artifacts. It seems that the rotation data is not interpolated properly by the time blend and just keeps flipping between the original frames. Does the time blend also work with rotations?
The original simulation has some very fast rotations and movements, especially when the impacts happen. Maybe I need more substeps in DOPs but this will change the look and speed of the whole simulation? Is there a better workflow of doing this retiming stuff, especially when it also includes particles and smoke sims?

Thanks in advance.

[ranxerox]

Hi everyone,

 

I´m fairly new to houdini and this forum already did a fantastic job answering my questions just by reading through all of these posts. But now I got a little stuck and haven´t really found a clear explanation for my problem.

I have done a RBD Simulation, which is prefractured, simulated in DOPs and cached out as bgeo. Afterwards I created a time blend and time shift node to retime the simulation (not linear, maximum is about four times slower). The slowdown of the translation data is fine, but the rotation has some strange jumping artifacts. It seems that the rotation data is not interpolated properly by the time blend and just keeps flipping between the original frames. Does the time blend also work with rotations?

The original simulation has some very fast rotations and movements, especially when the impacts happen. Maybe I need more substeps in DOPs but this will change the look and speed of the whole simulation? Is there a better workflow of doing this retiming stuff, especially when it also includes particles and smoke sims?

Thanks in advance.

 

 the interpolation you are doing between frames is probably just a straight linear interpolation,  which isn't strictly correct for rotations..  one thing you might do is output your rbds as points (on the dopimport use the import style "create points to represent objects")..  this will give you points with an orient attribute.  You can then create subframe orientations using a quaternion slerp in a point vop or wrangle.

 

 -G