After Effects 3d Camera Tracker Scale Definition

The new After Effects (CS6) 3d Camera Tracker/Solver is very accurate! But it lacks a way to define the scale of the scene. My feature request would be: let us draw a line on top of the footage, and define it's real life length, so the tracker's feedback is in the right scale!

Why?
Because in vfx, scale is very important. E.g. when compositing a 3d model of a car on a road, it's good to know that the scale ratio's are the same. In the current situation, the road can be 12000 meters wide, and than it's not easy to make the car the right size.

We want virtual sliders througout the suite!

We want virutal sliders to change type size and leading!

Just like in Photoshop:  press CMD (Mac) and slide the mouse to increase/decrease size.

This should be enabled througout the suite!