Randy's Black Belt Camera Projection

As discussed on today’s Patron’s Chat, and as I foolishly promised to post, here is a fun trick for texture extraction and reprojection using a 3d track and action cameras. It’s a bacon saver.

  1. Get yourself a good 3d track of your scene. Locators at points where you’d like to place surfaces are nice, but you can always use Find-A-Point to get them after the fact.

  1. Attach a surface to a point on the plane where you’d like to do your work, and make sure your surface is aligned to the same plane

  1. With your background selected in the action media list, attach a diffuse map to the surface, and set its mapping mode to Projection: Camera1 (or whatever your hero tracked 3d camera is called)

  1. Attach a camera to the axis of your surface. Frequently the camera is on the bottom looking up, you may have to flip your surface around to have the camera looking down at the surface. You’ve just created a downshooting camera that will capture a static version of whatever it’s pointed at, which is very handy. Much more handy than what I used to do, which was track perspective grids to geometry like a fucking animal.

  1. Create a second action output, make sure your surface and diffuse map are active (I typically just hit All Objects out of sheer laziness, but you can actually make as many cameras and outputs as you want from a single action, which is also quite handy).

  1. Notice that on output 2, you now have a very stable (or as stable as your 3d track, I suppose) image/plate/texture, onto which you can place, say, a picture of @andy_dill or do whatever paint work you desire.

  1. Duplicate your first action node (I like Duplicate With Connections for this, because it saves you a bunch of tapping and reconnecting. Connect the output of whatever work you’ve done on the flat image to the input layer formerly occupied by the color source.

  1. Delete the diffuse map and camera from the surface.

  1. You are done!

Some things to keep in mind: The orientation of the original surface is pretty key, so fiddle with that while you scrub around on the camera2 output to make sure your texture is staying perfectly stable. Only after you’re satisfied with that orientation should you duplicate your action setup to reproject, because the source and destination surfaces need to be identical. You can scale and rotate the surface to make it work for your purposes, but you should make sure it’s pinned to the origin axis for the background, xyz should all be 0.

Finally, and most importantly, I got this from @p2FX so thank you again for that, Patrick. I don’t know where he got it, probably Dill, who no doubt discovered it on some manga forum somewhere. It’s my understanding that this is similar to something @DannyYoon has placed on the portal, but I haven’t tried that one and frankly have been too dumb to comprehend most of what Danny has told me for about 20 years now. I stand on the shoulders of giants, in case that’s not clear.

If I got any of that wrong or skipped any steps, I hope they will drag me mercilessly for it.


Rotate the projected-upon card to negative 90 degrees and the camera hanging off it will point down at it. Usually.

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Thanks for posting this!


Thanks Kirk, that is awesome. This by the way is the feature request from the Feedback Forum. Don’t know if you can still upvote it, as it got accepted, but whatever helps…




FYI most of the time when someone posts a procedure they name the topic after the person that developed the procedure, not the whiny asshat that requested it.

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Where’s the fun in that?

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Thank you for that!

@p2FX also showed me this trick a while back, which had me tickled… Attaching a camera directly to the surface… Who’da thunk? I always thought it’d be a lot more complicated voodoo to get the camera frustrum aligned to the surface.

It also works well with the new Camera Analysis but again, sticky plane is only as good as the track. YMMV.

Used it to extract a ground plane texture at edge of frame from a really distorted wide angle lens. Regular track wasn’t solving, but the Camera Analysis gave me something I could at least work with.

Thanks for posting @kirk!

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One thing I do cos I rarely get a perfect track is do a secondary 2d stabilize using planar tracking, uvs, 1pt, whatever, and then un-stabilize it before plugging it into the second action.

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Yeah, 100%.

Stabilize the stabilized.


One thing I’d like to play around with is using this within an undistort/redistort workflow via syntheyes or similar, but my grasp on that process is still iffy at best.

Right! Using @bryanb ’s excellent UV stabilizing gag from yesterday is a great intermediate step for fixing all kinds of evil shit before reprojecting.


Nice one Kirk! Would love to see a video of this!

Try to keep warm out there!