I made this simple animated thingy in c4d:
It's a recursive scene - think infinite zoom, like zooming into a picture that contains a smaller version of itself, and that smaller version also contains a yet smaller version, etc. - just in 3d.
Read the clip description on YT if you don't get it, or watch the clip.
It's not the final product or anything, just a test.
The ratio of the bigger scene to the smaller scene is 10:1. Meaning, each consecutive level of zoom is 10 times smaller, for simplicity sake. The camera zooms in. At frame 0, it has a keyframe that points its zoom level to, say, 1. And the last keyframe of each zooming makes the zoom level, say, 0.1.
Problem is perspective, though. If the F-curve connecting the two keyframes was set to linear, it would look like the zoom speeds up and then suddenly stops when it reaches the next zoom level, and repeating that pattern, instead of a relatively smooth-looking camera movement you see in the clip. I am not sure how I achieved that, but I set the F-curve to spline and fiddled about with the curve shape until I was like "Guess that has to do, I can't possibly do a better job", which took me a while.
But look at the blue car. It too has keyframes at 0 and the last frame of 1 zoom sequence: for position and size. Position changes in this fashion: 10 + 1 + 0.1 + 0.001 + ... etc, each level of zoom "adding" a 1/10th of its actual coordinates - since every consecutive iteration is 10 times smaller, right? Thus its size decreases from the factor of 1 to 0.1 to 0.01 to 0.001 ... etc. Since the camera's APPARENT movement is linear (while its ACTUAL movement, to zoom in, is this fucking spline that took me forever), the blue car's size should stay roughly the same throughout the whole animation. But with its F-curves set to linear (size & position), it doesn't look to smooth.
How do I compensate for the camera's movement?