Target Z of Camera Target

How exactly does this function work?

I created a test map: I placed a knight on the map. I made a trigger than locked the cam on the knight. Every second, I would display the "Target Z of Camera Target." On the map, put some noise in one area, then a series of cliffs in another area. I'm not getting correct values. It gives the terrain height at base level as 0 (I think it's cliff level 2, maybe 1).

It seems to be getting an average Z value for a region centered at the target. Anyone know how big this region is, or does it somehow depend on the camera? I know that it doesn't depend on the angle of attack, but maybe field of view?

Ok, I just tested field of view, far z, and distance from target. Changing z offset just increases the value returned by (z offset) amount.

I'm pretty sure that it's returning the average terrain height in a circular region with the diameter approximately the width of the screen.