I have a small video tutorial for this question at youtube. [video:youtube]http://www.youtube.com/watch?v=KIb4LTtqy9Q[/video]

In this video I use the marine reference model, a floor and a wall with textures from dexsoft. The textures are 512x512 pixels large. If we define that the marine model is about 2m in height including boots and helmet, this would also define that 256 px equals 2m and 512 px is about 4m.

If you play unreal tournament you will notice that the doorways are always very large compared to the players size.
Why is this the case? Because this game needs room for action and if you want to avoid some hits, you have to dodge (jump and jump again in mid air).

I hope the visual quality of the video will improve during the youtube post processing. It is a highres video (1200x800) but currently only the lowres is avaiable.

It is my first video tutorial, so please relax and ignore the noisy background.