Optical Flow?

[ivan]

any way to compute optical flow in Houdini?

anybody ever played with opticla flow?

[edward]

Looking at this paper, I don't see an easy way oft-hand as you need to solve a least squares problem from the image sequence. There isn't an easy way to use the HDK's matrix solvers from Houdini. I think the HDK probably has a matrix solver that could do this (UT_MatrixIterSolver?). One idea is perhaps to create a custom HDK CHOP that let's you do this.

You could probably do the various partial derivative estimation in COPs though by just shifting the image sequence and applying the formulas you see in the paper (like in a VEX COP). So depending on your needs, those may or may not be good enough.

As for importing into Houdini, could probably just create a 32-bit floating point tiff and stuff your vector data into the RGB components. You would just treat data the like velocity and could use it for pseudo-motion blur like in the Velocity Blur COP.

I'm assuming that your images aren't computer generated. Otherwise, you could get Mantra to render to your world-space velocity field and have it projected into screen space. Just a thought.