I've been sandboxing to learn about 3D pictures. Seems extremely powerful. However, I'm struggling with the basics of what the "length" units mean. There's no description in the help files of any of them to give a clue. Googling around doesn't produce and answer either.
What do these relate to? For example, I have a 3D picture control with a content bounds of 400 x 985 pixels. I'm trying to fill the screen with a very flat box (faking a background image) of the same size. When creating the box, it seems I need to set X and Y lengths to both be approximately 3.32 to fill the content bounds. I can't for the life of me see how that relates to pixels or some sort of ratio, or whatever. What do these numbers represent?