I'm matching 3D layers in AE to footage shot with camera. When I try to work with this I seem to work with sizes that AE can't cope with. In real life a layer should be 20 meters away from the camera. When I try to set these settings it jumps back to about 12 meters. ALso the camera can't be offset more than about -12000 mm (12 meters). That's no good. After Effects seems to work with tiny sizes. (you can't use meters or even cm as units, just mm). When I look in top view in my windows everything is out of reach. can't find the camera, can't find the layers. So...of course it's me doing something wrong and AE should be set differently, but how?
AE thinks in pixels and assumes 72DPI. Therefore you'll run out of valid pixel values pretty quickly and it's unrealistic to work that way. Simply scale your scene/ measuremnts accordingly.
Working with footage from a camera and matching CGI gives us the possibility of adding the lens settings like filmsize, focal length and angle of view to the camera settings. That way we can mimic the camera in AE to the actual camera.Also using real life distances like the distance to a table can be used to create correct perspective, especially if something generated in AE changes from z depth. Therefor I use known sizes and distances. I'm happy After Effects lets me since it has the option of using milimeters. A small size, but still a true real world size. Using this kicks everything off the screen though. Scaling everything 10 times, so thinking a mm is actually a cm would make the real life sizes and camera settings unworkable I'd think. I can imagine I'm doing something wrong, but don't know what. It just doesn't seem right to me having to scale everything when real life sizes are used. What else are they there for?