How do I convert a set of moving objects to a set of relative static objects

[stevesideas]

I have a tank driving down a road and a camera that sweeps past it and also rotates around it always looking at the tank. All keyframes are baked. How do I keep all the relative animation but make the tank static at the origin? Basically I need to negate all world space movement.

[stevesideas]

Well, I managed to work this out. If I create an expression on a secondary position and rotation layer that negates all the original values of X,Y & Z it will become static. This is the expression I used: [original_posX,original_posY,original_posZ]*-1 where 3 new controllers were applied to each of the same nulls x,y & z. Same for rotation and hey presto

[stevesideas]

ok. This works perfectly for position but for rotation it removes most of it but not all. Very odd. These are the two rotation graphs of x,y & z. They match but the expression values are inverted. Not sure why this isn't working.

[stevesideas]

Okay. For some reason the axis order need to be changed for the float expression layer. Working perfectly now.