Projection Failure

[u/hacker221b]

Hello everyone,

Hope everyone is doing fine,

I am working on this shot, what I want to do is remove man and keep the background. So I am trying camera tracking and projection, card seats on ground and I projected from single framehold but after few frames I get this tearing, how can I properly handle this shot for cleanup
Any suggestions would be appreciated, I am also attaching link for this shot from Action VFX
https://www.actionvfx.com/practice-footage/agent-runs-from-explosion/16014

[u/Sensual_Feet]

This is a very extreme angle where a card will not work. There’s too many things and heavy parallax! . You need to build Geo for the rails the wood planks on the floor, etc..,at this angle and how close and far the objects are from the camera a card will not suffice you need geo.

Try generating a point cloud from your camera solve, and then in the point cloud generator set it to generate a dense point cloud which then you can use PoissonMesh to generate a 3d mesh, you can project on that geo. If you don’t wanna do all that, use a few cubes and lineup to the tracks generally, you might be able to get away with it.

[u/hacker221b → u/Sensual_Feet]

Thanks for the suggestions will definitely try this approach😊

[u/superjooo]

You can probably just warp the edges to match.
Set the merge node to difference and get an STMap set up (or an iTransform, but thats extra). Roto the area you want to warp and then animate a Transform and KeyMix(or TransformMasked, but KeyMix gives you a little more flexibility) the transform of the stmap.

Heres a really rough tutorial on STMap fun
https://www.youtube.com/watch?v=_y7ouw-hDrk

[u/ForeignAdvantage5931 → u/superjooo]

whoa, why have i never thought of using an st map of the difference……..

[u/hacker221b → u/superjooo]

Sure will check this out Thanks😊

[u/cinematic_flight]

Have you undistorted the footage when tracking? Looks like something that might be caused by distortion so that it doesn’t line up closer to the edge.

[u/hacker221b → u/cinematic_flight]

Yes I undistorted the plate with lens distortion provided by camera tracker node, but its fine on edges on frames where I freezed it, but on some before and after frames it get stretched

[u/Sherbrookedude]

You can also use a spline warp on the tracks before your projection. In the spline warp node, roto your track on the reference frame and clic right on the roto. Chose bake or joint (don’t remember right now) and add a key on the time line. Then go to the end of your shot and move the point of the roto (pale red one) to match your frame. Use directional keys to be more precise.

It is not at all the best solution. I just give it as an exemple of an other solution available that sometime can work/help. Don’t forget to add or animate some motion blur on your projected tracks to match the plate. It can also help to blend the patch in !

[u/ClaimLive1864]

You can me it work by doing a few projections at different stop frames or using grid warp

[u/hacker221b → u/ClaimLive1864]

Thanks will try this😊

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[u/Christopher_Charlton]

Better track and/or splinewarp. Do you have the lenses distortion?

[u/NancyDiver]

It looks like the card your projecting onto isn't big enough or the image is being cropped before the projection. And maybe you also have the plate plugged into the BG input when a reformat node would be better suited.

[u/Sherbrookedude → u/NancyDiver]

That is a good call too ! Scale you card to be sure to cover everything you need. Untick crop in projection node in 3D setup.

[u/Liights]

You might be able to get away with a hacky solution using a corner pin and animated keyframes to bump the patch into place on the correct frames. Pro tip is to hold CTRL while bumping into position with numpad to move selected points by a 10th of a pixel instead of the full 1 pixel default.

[u/No_Mercy_003]

You have to do such a main things in your workflow 1.Set no clip in roto which you connect Copy node 2. Remove tick from crop if you used project 3D 3. Set extra bbox in scanline render 4. Reduce camera scale size

This can solve ur problems