animatrix

Temporal Oriented Bounding Box (OBB) [Rigid Transform SOP]

Added 2020-09-01 16:53:31 +0000 UTC

When computing oriented bounding box (OBB), it's very desirable for the bounding box to be robust, i.e. not flip arbitrarily when the input geometry is animated.

Bound SOP doesn't support temporal data. To compute a robust oriented bounding box that takes temporal data into account, we first need to establish a static reference frame, create the oriented bounding box using this geometry and then transform the static oriented bounding box by the difference between the reference and the target geometry.

You can use the built-in Extract Transform SOP to achieve this. Unfortunately this operator does not support non-uniform scales, so it only takes you half-way there, but Rigid Transform SOP does.

Here I didn't create a new operator but rather use the default Bound SOP along with the Rigid Transform SOP, which shows how versatile and powerful this operator is.

https://www.dropbox.com/s/5bd7uftfqr33vhx/RigidTransform_SOP_Animatrix.otl?dl=1

https://www.dropbox.com/s/tgkdpsu50lfxhcq/temporal_bound.hiplc?dl=1