Projecting on to an animated Geo

I looked at other posts but they didnt seem to solve this problem i have…

I have an alembic GEO that tracks to an arm which i need to project and track on to. There is also a camera for the scene

As a geo it has hardly any options , ive tried adding diffuse map with the camera paused on one fame but it only tracks to the camera , not the arm geo.

Ive tried using old school projector but every combination i can think of isnt doing it.

Im sure im missing somthing and hopefully someone can sort me out , any ideas???


hi @Mark_Epstein maybe this is what you are looking for:


thanks , yeah i saw that post and tried it but no banana. Im not sure Exactly what should be connected to what . Ive done this using flame surfaces i have warped myself but not with externally provided Geo where the animation is baked in + using a camera.

Im not exactly sure what “stick the image to the geo with UV’s” means?

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can you use an axis to link the projector directly to the geo? that will then move the projector wherever you move the geo.

Take a conection from whatever is the main overall control axis for the geo, connect it to your projectors axis, then postion the projector to get the effect you want.

the axis’s are all at 0. the alembic geo for the arm is animating but it is baked in , there are no transform controls animating that i can actually see

In really simple terms a UV map is how 3D artists attach their textures and materials to a model so it sticks to the surface consistently, wraps around the edges of geometry properly and generally “looks correct.” I’m not a 3D artist at all but my understanding is at creation even primitives like cubes and spheres come with default UV maps and those come across to flame intact (most of the time) and can be read by Flame software to also “stick” images or textures on geo without having to bend or warp it ourselves.

You don’t need to do any parenting or attaching of maps. You do however have to carefully line up an old school projector directly in front of your imported geometry on whatever frame you are parked on and project your image onto it to your liking. Once you’ve done that you mash the button I specified in the linked post and you should be able to scrub through your timeline and watch your image magically stick to the geo no matter the animation. To be clear this works when you want to map an image onto part of the geo (like a logo or texture you painted) this is not a workflow for assigning materials to the entire 3D object.

haha yeah I have used UV’s before It was just the language i didnt totally understand. In this case it is a 3d model and i need to project a still or a surface to it entirely in 3d

Not sure if it helps, but a common workflow is to render a Resting Position pass in a 3d software and the use it to do Camera projections based on Position data. The result is the projected texture sticking to the geo deformation.

This is a common method in Nuke… not sure Fusion

I have always been lucky enough to push this type of thing back to our 3D department but I have been facilitated by this Ls_glue matchbox by @lewis

We have gotten it to work for us yet. The next time we have some breathing space I will try it again but my knowledge of any 3D software is zero.


There you go!

i have never used alembics - i assumed they came into Action the same way fbx models do (with loads of axis linking to every bit of geometry)

I actually tried to follow along with this demo a few months ago and I couldn’t get it to work. Has anyone made a more up-to-date demo of this?

I too have never been able to get this to work!! it would be so useful


Currently i got the CG guy to render a checkerboard mesh and i have done a perspective Planar track on it… and its just about good enough… The actual GEO i have isnt a perfect track so i need ectra contriol of a tracked bicubic to make litlle adjustments

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Got partial success with Ls_GlueP.
Used Blender to generate the Pref position AOV.

Followed the tutorial from @lewis and the were a couple of things I adjusted.

  • Matching the FOV to the original camera didnt quite work… so had to tweak it a bit to get the projection to line up.
  • In Blender Z is UP so had to reshuffle the Pref RGB as RBG
  • Also had to to got into the Space conversion tab, enable Convert View to world and set the World Y rotation to 0.0

Files if you want to play:


Another example linking a separate camera as a projection source.
Camera position and rotation are linked to the GlueP projector values.
Action 3d view/geo is just for reference only.


Nice - I never tried this with Blender or other Z-up apps so didn’t think to add the axis rotation for it to GlueP, the conversion tab in the shader is meant for converting camera-space to world-space really and I’m not sure it will do exactly the right thing :thinking: Looks like you figured it out but if in doubt you can rotate the pixel values using Ls_Vops instead:

I also just took a look at the FOV difference because it should line up exactly really - I think there’s something weird with the way Blender exports cameras to Alembic because if you look at the Film Back tab in Flame on the imported camera, the aspect is 1.5 where you’d expect 1.77777, and that affects the FOV. If you use this calculator: Camera Field of View Calculator (FoV) …to get an FOV number for a 50mm lens on a 36x24mm back set to 16:9 crop the number you get is 22.9 degrees, and if you use that in GlueP it does match exactly. Kinda annoying, haven’t had that issue with Houdini/Maya…

Screenshot 2022-11-19 at 21.41.40

Glad it worked eventually anyway - it’s super handy but there are soooo many things to go wrong setting it up, I usually end up opening the 3D scenes and exporting the camera/rendering the P or Pref passes myself to make sure they’re right :weary:

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here’s a quick demo of using the projector to stick a 2D image onto an animated 3D model. Hope it’s useful!


@lewis Thank you so much so much for looking at the setup… and for making the tool in the first place. Yeah something is of with the way Blender is exporting the camera. Will look into it eventually. I included the blender file (with the Pref setup) in the attachment, in case artists here need it.

@TimC Thank you as well for the clear video. Your approach I guess will work for geo caches with simple UV distribution. It doesn’t work for more complex models and UV sets. Thats where @lewis matchbox magic comes to the rescue.

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Just checking in on this , thanks for the 2 updates Lewis and Tim!

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