evp_uk wrote:
So am I correct in thinking that with the ps3 cam in monochrome mode I can capture using 4 cameras on a single dual core laptop with 2 usb buses at 60 fps? Is 60fps the max frame rate of Ipistudio or is it video dependent? (incoming video rate dictates capture rate)
thanks in advance!
Alex.
You can't capture monochrome PS3 in iPi Studio, and you wouldn't want to because DMC needs the color data for separating the background from the performer and also for tracking the performer's body parts.
With the dual core laptop you may be able to capture 640 x 480 at 30 fps, which is fine if your motions are not too quick. You need 60 fps to reduce motion blur and to get this frame rate you will need a quad core system and probably a very fast drive. Also, you need to be sure your laptop actually gives you two controllers for the cameras. If indeed you have two available USB controllers, you can use two cameras with each controller for a total of four. At this point, however, your bottleneck will probably be your capture drive. (This is where I gave up using a laptop for motion capture.)
FYI, I'm now using a quad core system with an internal SATA3 drive dedicated to video capture, and it easily captures 4 synchronized streams of 640 x 480 at 60 fps with no dropped frames. The best I could do with my old dual core laptop was 320 x 240 at 30fps with no dropped frames; I was still able to get good results with this, but it wasn't as precise as what I'm getting now with the quad core system.
It's a hassle to lug this bigger computer and keyboard from the studio to the shoot location and back again for tracking, but the improved calibration and motion capture quality I'm seeing now is definitely worth it. FYI, I still bring the laptop to the location; it's handy for video and music playback during capture to help keep multiple character performances synchronized.
G.
Edit: Yes, 60fps is the current max rate. So far it seems to be fast enough for the motions I'm doing. In a recent shoot, we had some some fairly fast arm movements (simulated guitar playing,) and I was a little surprised that DMC was able to track this. Unfortunately, DMC's Jitter Removal completely removes this subtle but significant motion, so I had to stop using Jitter Removal. Same was true for the harmonica and cowbell performances, which both featured small but important hand movements.
However, not using Jitter Removal has its own issues since Jitter Removal actually does a lot to help stabilize the feet. To solve this problem, I had to come up with a different solution for the feet using my 3D app, but I understand that the iPi team is looking into this problem.