Being a complex composition, a thorough preparation had to be done before filming.
we shot the film and we shot a clean plate in the exact position.
I used this clean plate to remove what was not necessary during the composition.
To clean the shirt, I had to hold frame a part of the shot where the shirt was good enough and rotopaint it.
I then use this rotopaint along with a tracker to hide the parts I needed to. then I added a grain on top of it.
I lighted the maya scene of the arm to match the lighting scene of the shot. I rendered it with different passes
including occlusion. I comped it on the shot and used a grade node in nuke to match the black point and white points.
I then played with the gamma to make sure the robot arm matches the scene.
After that I did an overall gradation of the scene.
every shots had approximately the same process with new and different challenges.
in shot 2 I had to use a technique called multiple frames grid warp to fix the part of the arm witch was lost, basically frame hold
parts of the arm at different frames, track it, and place it where it needed to be place to fill up the lost part when removing the grey arm.
I should add that the modeling, surfacing, rigging, lighting, animation and composition has been done by myself