== "Focal point" == 

 This page mentions "focal point" twice, and Camera matrix links focal point to this page via a redirect. I think the author is trying to talk about the camera center. If so, that's misleading at best. In as much as a pinhole camera models a real camera, the focal point would better be the principal point. Either way, I've never heard "focal point" used with precise meaning in computer vision/graphics. Shall we replace "focal point" with more-precise language?