This really simple shader let you combine 2 inputs channel into a new one. There is already something like that in AE, but I believe it is only working in 8 or 16 bits. This one is working in 32 bits (thx pixel bender). I just did it because sometimes I do need to combine map datas (as normal map & height map) for my shaders, since Pixel Bender is limited to 2 inputs.
If you are doing Matchmove, you probably bumped into Lens work-flow issue, where you have to un-distort the footage in your matchmove software, then track it, and export a new undistorted footage, so your client can compose the 3d rendering on top of it and then distort it back.
I don’t really like this work-flow, since for instance AfterFx do not have Cubic Lens Distortion FX and it would be really hard for the client trying to match the distortion back.
Thanks to Jerzy Drozda Jr (aka Maltaannon) for his great tips about Pixel Bender.
So now, you can create a new comp with your distorted footage > pre-comp it > undistorted it with the shader > track it in syntheyes > export the camera to a 3d package > render the scene > import the render into your pre-comp > desactivate the shader. Should match perfectly
(yeah I know, PFTrack grid with Syntheyes … not cool ! :p )