[Greg McKaskle]

A white paper is or should be posted on the NI site before too long that explains some approaches to processing images.

There are a number of techniques for calculating distance, but the straightforward one is to use the known width of the target and the information about the camera lens optics. You can find the optics view angle on the Axis web site.

Basically, if a target width is known, camera resolution is known, and lens info is known, you can calculate distance pretty accurately to a target located at any of the heights.

Greg McKaskle