Depth estimation from live video stream in matlab
Since you have two webcams you can reconstruct the video scene using the frame sequence. If your webcams happends to be stereo pair (with known extrinsic parameters aka rotation and translation) your task becomes pretty easy. On the other hand if webcam locations are unknown the problem gets a little trickier, but it can still be solved using matlab's computer vision toolbox.
In both of the above cases the scene reconstruction is accurate up to a scale factor. In order to calculate the depth in real units you need length knowlegde about an item in the scene. i.e the edge of a tracked square is 15cm.