Originally Posted by
not sonic
i dunno dude. theres only so many ways to do motion tracking.
if we focus specifically on vision based tracking there are a few different ways to do it. computer vision is also a relatively newish field and especially when you consider consumer grade applications for high quality video game experiences. you have to consider a large number of factors; cost, reliability, ease of use, different environments, fidelity, etc.
the only negative of the lit ball aside from possibly aesthetics and battery life, is that it can be potentially distracting.
if it were replaced by a reflective ball then there could be issues with differentiating between player 1 and player 2's controller. the reflective balls could be patterned or colored but the effect wouldn't be as easy to determine as a different bright color. reflective trackers would also be subject to problems in low light.
you can do infrared tracking though. it could essentially be the same design but the ball wouldn't be visibly lit. i do not know if you can easily differentiate between various "colors" of infrared to maintain unique tracking. doing ir tracking though would require an ir filtered camera. most webcams are capable of it but then you wouldn't be able to do the simultaneous stuff like eye pets with one camera. so to maintain the same functionality you're increasing hardware, cost, and processing time (now youre dealing with two separate images) and decreasing ease of use as now the two cameras would need to be calibrated properly.
you can use no trackers like kinect too. but with the current consumer grade technologies and to keep costs low youre looking at lowered fidelity and increased lag and processing time.
of course stuff like kinect is the future but in the mean time to provide an enjoyable play experience (low latency, responsive, etc.) trackers are required to keep costs low and the move is probably optimizes the most possible factors.