i like it. it looks like it would work. but what if i was on its side so that safety glasses could be easily modded across the top rim. so it's right, middle, left. instead of top, middle, bottom.
Projection of a custom IR beacon with four LEDs in a non-planar arrangement onto the Wiimote camera's image plane.
So to track 3/4 points we need a way to "know" that when a point moves to a new location where it moved from so we know that it's the same point. I don't have my wiimote yet so maybe I'm off base and maybe the wiimote libraries already help coordinate this information.
Also is there any reason why it says you need 4 points (not in the same plane) to track a 3D object.
I personally, since having seen Johnny's and Olivers videos, have been thinking of a way to track a sword in 6DOF. That's
Oliver Kreylos: "and predicted target point projections are matched with camera observations on a nearest-neighbor basis"If the ID by radius does not work I think it is impossible to solve the problem with WiiMotes in 6 DOF. One would always have to make restrictions, guess or take the brute-force approach.
Oliver has a rudimentary light saber demo.
Oliver's predictive method seems pretty good.
In Johnny's video on the automatic projector calibration, he mentions that they use predictive modelling when one of the sensors (fiber optics in this case) falls outside the view of the system.
There are oodles of mathematical papers at his site:http://www.cfar.umd.edu/~daniel/
FreeTrack uses a version of DeMenthon's POSIT algorithm. I can't help but think that FreeTrack could be adapted by throwing out the initial image analysis step that finds the LEDs and just substituting the output from the wii.
As for identifying the LEDs, how fast is the refresh rate on the WiiMote's CCD? Would it be possible to chirp each LED with a unique time signature? Or continuously blink them each with a different blink frequency?
Myself, I'm interested in something like a 6DOF mouse for the analysis of 3D image data. I want to be able to move the wii around and have my 3D data rendered following my motion. There are expensive solutions out there. This is the first cheap solution that looks practical.
Quote from: HighDesert on January 21, 2008, 08:47:42 PMOliver has a rudimentary light saber demo.I know, but the direction of his sword is very restricted, the WiiMote must be pointed at his beacon for 3D tracking.
Quote from: HighDesert on January 21, 2008, 08:47:42 PMFreeTrack uses a version of DeMenthon's POSIT algorithm. I can't help but think that FreeTrack could be adapted by throwing out the initial image analysis step that finds the LEDs and just substituting the output from the wii.Yes, this might work. As I understand it the Wii implements the image analysis in hardware which is a great advantage.
The issue is really just point identification. If we assume that the refresh rate of the CCD is 100Hz (which I sincerely hope it is), then Nyquist[1] says the freq of the LED chirp (50% DC) needs to be less than 50 Hz. Most remote-control IR diodes can handle 40 kHz[2], so no problem there. Some error will occur, but as long as the chirp frequencies are known, it can work. A simple micro mounted inside a sword (I really like that idea) or on the back of a glove[3] can handle this easily.
Unfortunately, the "geometric LED curtain" doesn't work with the wiimote. The device is limited to exactly four points of detection. We should consider this lucky since Nintendo had no reason to detect any more than two.