The setup I've been using lately seems to work very well for me: It's a half-circle arrangement, with the cameras about 2 to 3 meters up, and far back enough to see the full figure of the performer with plenty of space around him. I have to check, but I think the cameras are between 3 to 4 meters from the performer, which is about as far as I can place them in my current shoot space. (I wish I could put them back farther.)
Also, if you're using the PS3 Eye camera, make sure you have the lens set to the wide setting. (I think it's towards the blue dot, but you can check this in Recorder.) Setting the lens to wide gives your performer more space to act in. Don't worry about lens distortion, it's not a problem with this camera and DMC.
When shooting the calibration video, try to keep the Maglite in view for all cameras for the entire duration of the video. This is easy to do in a half-circle camera arrangement, and very difficult in a full-circle because at some point you're body will probably occlude the light. IMO, this is a good argument for sticking with the half-circle arrangement. The half circle arrangement also makes it easier to manage the background, as it is much easier to clear half a room than a whole room.
You can see what my current setup is by looking at this video:
iPi Studio Motion Capture Test: Sword PropI'm using a solid chromakey backdrop and floor tiles here, but a green screen environment is NOT actually necessary for good tracking in DMC. What's important is to have an uncluttered background to help the software matte out and isolate the performer from. Plain walls and simple furniture should be fine, but glass windows and highly reflective picture frames on the walls are not. The more complicated the background is, the more difficult it becomes for iPi DMC to see the performer's limbs clearly.
It's also important to have a clean plate in the first 30 frames of the project; I believe this is how iPi DMC mattes out the background. If you don't have a clean plate at the beginning of your video, you can drag the range to a section of the video that does. (I'm hoping that a future version of iPi DMC will let you load the clean plate video separately so you don't have to worry about setting this feature for every new video clip.)
Finally, when setting your T-Pose, make sure you alternate between Refit Pose and Analyze Actor Appearance several times. This apparently helps DMC optimize the rig and improve its matchmoving ability. Don't forget to save your Actor and Project before clicking the Track button.
When tracking is done, review the motion by clicking Play. If it's a little jittery (and it probably will be,) click the Jitter Removal button. This post process seems to very work well, especially for the feet. Remember to save your project.
Hope this helps.
Greenlaw