Here is a little motion control scaling test I worked on at MAKE as a proof of concept for doing scaled shots. There is no tracking or fudging going on in either of the two composited shots, they are just garbage keyed and laid over each-other. Using some simple math, and a plum line we were able to scale the camera move to match the same subject, just 1/6 the size! The motion control setup we were using is the super lite and configurable camblock products.
Here are a few of my chicken scratches from when I was figuring out where to scale from, and where the focal points were going to be for the shot.
It ended up being pretty easy to lay out, I just measured out a right triangle from a fictional origin on the ground, that origin point was behind Sam, and everything got scaled from there. Just multiply the distances by 6, and make sure the second triangle is aligned with the first, and you are most of the way there. After taking into account the height of the sensor on the camera, to the the origin point, subtracting the original height, and adding back on the multiplied distance, we just had to raise Sam up a bit to get it to match.