I don't know much about picking terrain (sorry) but I can help you out with your PS question. First off, I interpret your question to mean you want the screen pixel dimensions of the object (your question is a little unclear.) Assuming that, there is no built-in command but in the Code Archives there are example codes to find the bounding box around an object, what you need.
how do i pick terrain with mouse
Blitz3D Forums/Blitz3D Programming/how do i pick terrain with mouseThe forum is locked. These are the original blitzbasic.com forums, kept so they can still be read. No new topics, replies or edits can be made here. To join in, head over to the Blitz3D+ forums.