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A Closer Look At The AimTrak (with video goodness)

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brandon:

You guys may find this interesting..  :)

http://muonics.net/blog/index.php?postid=26




a webcam tracking a laser pointer.

RandyT:


--- Quote from: AndyWarne on October 24, 2009, 04:10:45 pm ---Dont understand at all. The camera cant always see the center area, it moving with the gun...If its pointing at the top of the screen it loses the bottom emitter and vice versa. The cameran can only see both when the gun is aimed near the center of the screen.

--- End quote ---

Correct.  Right now, the system works pretty well with only one emitter in view.  The only time it would ever see two is of the camera were pointed somewhere in the middle of the screen.

The reason one needs to be so far back is because a single top mounted emitter gets lost, at close distances, as soon as one starts moving downward.  This wouldn't matter with a dual emitter system, because the gun would have switched over to the bottom emitter by time the upper one was lost off image, and vice versa.

With some calibration tricks, this arrangement would not only let one get closer, but should be more accurate, as each half of the screen has a reference which is more local to the actual position of the gun.

RandyT

AndyWarne:


--- Quote from: RandyT on October 25, 2009, 04:21:18 am ---
--- Quote from: AndyWarne on October 24, 2009, 04:10:45 pm ---Dont understand at all. The camera cant always see the center area, it moving with the gun...If its pointing at the top of the screen it loses the bottom emitter and vice versa. The cameran can only see both when the gun is aimed near the center of the screen.

--- End quote ---

Correct.  Right now, the system works pretty well with only one emitter in view.  The only time it would ever see two is of the camera were pointed somewhere in the middle of the screen.

The reason one needs to be so far back is because a single top mounted emitter gets lost, at close distances, as soon as one starts moving downward.  This wouldn't matter with a dual emitter system, because the gun would have switched over to the bottom emitter by time the upper one was lost off image, and vice versa.

With some calibration tricks, this arrangement would not only let one get closer, but should be more accurate, as each half of the screen has a reference which is more local to the actual position of the gun.

RandyT

--- End quote ---

The sensor is angled upwards so that there is approx the same amount of leeway top and bottom.
If the gun needs to work with either a top or bottom LED bar, it needs to know which one its looking at. You mentioned reversing the lower one. Determining which bar is which, using the reversal, means that both the left and right hand LED group of each bar needs to be visible at all times. This means the horizontal field of view would be worse than at present because in the current design only one LED needs to be visible and this one LED is located approx in the center of the overall field of view. The other led is used only when it can be seen, and is not used for the main X-Y tracking but only for correction purposes.

Endaar:

I have to say all this back and forth on the technical workings of a system like this and the considerations that go into a product's design are fascinating.

bkenobi:


--- Quote from: brandon on October 24, 2009, 06:23:05 pm ---BTW, What if you had an extra AimTrak facing the user that tracked the GUN?  add an IR LED to the gun that was in a position that could only be seen by the AimTrak facing the users and wouldnt interfere with the sensors in the gun.. 

--- End quote ---
If I understand your suggestion, there is already a gun that does this.  I don't think it was received well though.  I can't remember what it was called, but it basically had a web cab sitting on the monitor and the gun had a big growth on the top.  I think there was an LED in the tip of the gun and another in the tumor.  Supposedly, it could work with multiple guns.  I just wish I could find a link.

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