Looking for a little 3d camera halp

I have a dolly shot tracking left to right. mid way through the shot a grip cart shows up from behind a bush that the client wants gone.https://f.io/hF8jKqjx
Projections and such have never been my strong suit. looking for any advice, or opinions.

What specifically are you looking for advice on? The camera tracking? Setting up the projection?

I think that this will be a perfect case example for you to use 3D camera track and projections on. I’ll try and break my process down. It might be hard to explain in just words. I’ll see if I can dig up a tutorial for you from the Flame learning channel.

Analyse mono inside action will get you a 3D camera track. I suggest turning on forwards and backwards tracking. F7 will show you your tracking pointers and you can clean up any that track the walking actors by selecting those points and deleting.

The points you want to keep are the ones near to the object you are trying to remove. Select the ones in and around that area and select create axis. You now have axis creating a point cloud in 3D space.

You should now switch your action camera to the 3D camera that you have just tracked. Change from default to the 3D camera.

Now you need to find how many clean plates/layers/planes you need to create to remove the object. Obviously a background of the houses. Maybe the area around the trolly.

Anyway you should choose a frame and paint up a couple of clean plates. Do this for the background and any other planes you think you might need.

The trick now is to place an image surface into the point cloud. This can be anything like a solid white input. Do this for the background houses. Get the solid white surface the correct distance from the camera and the correct angle using the distance axis the camera track has provided you. Use the top view, side view and any other views that might help you get the perspective right.

The frame that you have painted up needs to be projected onto this surface. Duplicate the 3D camera and call it projectionCamera. Go to the same frame that you painted the clean plate and keep just that single key frame on the projectionCamera. This is the significant part. If you painted a clean frame on the last frame make sure you use a projection camera with only the last key frame. You can use as many different projection camera for as many different clean frames you need.

Use the diffuse map as a surface texture and change the texture to projection and chose the projection camera to the projectionCamera you have with only a single key frame.

Now when you look through the 3Dcamera you should see your clean plate move in convincing 3D space.

Now you just need to layer up any more clean plates on their various depth to finish the job. These projected clean plates can have mattes to help the comp. Be mindful of z-depth or turn it off entirely.

I hope that helps start you off. I’d love to hear how other people approach this.


You should totally see this LOGIK live breakdown. Some incredible use of projections here:
Logik Live Episode #03: Hyundai Spot Breakdown with Inti Martinez

These are some more basic intro tutorials from Flame learning channel.


Personally, I’d look for a 2D solution before going the projection route. That track is probably harder than it seems, especially since the objects you want to replace are occluded for a significant amount of time so you’ll run into a problem figuring out where in 3D space to place the geometry to receive the projection. Also, you might need multiple projections to accurately create the parallax and depth in that area. Also, it’s at the edge of the frame of a wide-ish angle lens, so there will be a fair amount of lens distortion to deal with.
I would start just seeing if you can do a planar track for the whole cart and see if you can track in a still for the sidewalk.


Or just cover it up with some green bushes





Personally I would try a motion warp track. A painted frame of the buildings based on the last frame of the clip projected should get you there with a little gmask tracer restore for the trees and the bush. The motion warp track process is explained very nicely in https://youtu.be/L7lRjsngKUQ.

Honestly, I would suggest Mocha Pro and a painted still depending on the resolution. A motion vector pass on big footage can become… long.

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@eversondigital is not that crazy setup a cam_projection. i usually use Difusse map on the Geo or big layer on the exacly Z you need.

made this exemple for you, You have Flame batch archive here: https://f.io/b9z1zXmM

** You will need to re-track camera, but you get idea on the Action setup how it works


When I am trying to learn a new technique, or improve on one that I am a little unclear, I just try it on everything.

My indulgent use of the perspective grid have become legendary at my company.

It helps to have an alternative technique up your sleeve but this way I get to know the limitations and sometimes surprise myself.

When I am under time constraints I will pick the approach that I think will be the fastest but one of the pleasures I get from my job is trying something new and different.

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