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I've nearly completed a Blender composite which has taken much longer than it should have. A lot of the problems have stemmed from the motion tracking not matching when the 3D work was done in Maya, then brought back into Blender for compositing, pre rendered image sequences seem to jitter/move in a skittish manner. I have managed to get around it somewhat by having to scale/translate in x/y to try to make the pre rendered geometry to match to the background plate.

My question is this, I have certain elements which are more problematic than the rest, I've created motion tracks for the background plate which track good. How do I setup the composite nodes to attach a pre rendered image sequence to anchor to a motion track marker, I also need to be able to offset the x and y and possibly scale the image sequence so that they fit and match the background plate. Each element will have a mask or two to mix into the factor of an alpha over node too.

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In the compositor you can connect an Input "Track Position" node to a Distort "Transform" node, interposing two converter "Math" nodes set to Add, to offset X and Y. Transform node has a scale slider also.

In the track position node, select the image sequence to be composite, set the object as "Camera" and choose the desired tracker (give them an appropriate name for easy selecting).

enter image description here

Another approach can be to perform the composite in the 3D world: use the Image as planes function to create the plates, set the material as pure emission with strenght 1; in the Color management set the view transform from "filmic" to "standard", set look to "None". In the Movie Clip editor select the tracker and press "Link Empty to track" and "Set As Background". In this way the background plate is set as Camera background, and an empty is attached to the camera and moved by the tracker's data, and can be used as parent of an emissive "image sequence as plane" object.

enter image description here

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  • $\begingroup$ Thanks I tried the former method. Due to the rendered image sequence already having a tracked camera providing the render output, and attaching it to a tracked marker it is effectively double transforming causing more jittery movement. The plate has slight roll in it so I can't use a static image attached to a track marker, looks like I'll have to keyframe it by hand. $\endgroup$
    – Helpme
    Commented Jun 10, 2022 at 21:03

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