Power Mesh & hold-out w/ Nuke

Ran into a problem w/ Power Mesh. I have a mesh on a background, that’s occluded by the foreground. I’m using the mesh to to place additional footage onto the background in Nuke. For that I’m exporting the tracking data as .amb file, and create a geo node in Nuke from that.

That works really well. But the geo node in Nuke is automatically cropped by the mesh boundaries, which makes sense.

In this case, the placed geometry and mesh should be ducking underneath the foreground object. So ideally the mesh would overlap, but be held out by the hold out mask. But with an overlapped mesh the tracking gets really wonky (not surprisingly). Without the overlap I have a gap.

Any ideas?

image

This show the mesh with away from the hold out for proper tracking, but the shape imported into Nuke has a gap between the mesh and the holdout on the face.

I tried tracking with a tighter mesh, and then changing the layer just prior to export, but that didn’t work.

Create a larger shape to create your PowerMesh at first, then before you start tracking, make the shape smaller and constrain to the area you need to track.

Also, make the holdout shape for the foreground objects MUCH larger than you think you should and keep them visibly on for the track so you can see if they impede your track as it runs. When I say larger than you think you should, I mean something like 20-30 pixels outside the edge of the object. That will help a lot.

Can you try that and let me know?

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Thanks. That worked. I was on the right track, but had the order reversed.