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Christos #1 19/03/2009 - 09h27

Class : Apprenti
Posts : 18
Registered on : 18/11/2008

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Hello. I am using a 3 point clip (SFH 485P, 100 Ohms, 9V battery, serial assembly, ~45mA) and a MS VX-1000 (modded, removed the IR filter and put a negative film in front of it). I have some trouble though..
If I look the clip en-face (straightly looking at the LEDs) the LEDs seem a little off-set. The dimensions are correct (although the bottom LED is 95mm away and not the default 80mm. I have entered that in freetrack) but each LED points at a slightly different angle. One is "looking" slightly on the right, another sloghtly on the left. Only by a few degrees. Is this a problem?
The main problems are though, that the field of view is pretty small.
Also, the webcam tracks the LEDs only at a very close distance. I must put my clip right in front of the webcam at 15cm in order to track. When I move to the back, the red dots become smaller and finally, they fade away. This is a big problem, as the distance between my head and the camera is going to be larger than 15cm of course...
Any ideas? Maybe I need to put a smaller resistor? (smaller than 80 Ohms).
I dunno what to do so help me please.
babasior #2 19/03/2009 - 10h40

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Class : Webmaster (admin)
Posts : 930
Registered on : 09/07/2007

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three things :

- Remove all camera filters !
- use your model tracking in black room ! (for test, and for understand if the problem is a filter problem or a low level of LED alimentation ....)
-  use threshold to maximize led point size ...

Is it your tracking is better ?

I think there is, perhaps, not enough power for your leds ...

I use a 3 dots cap, and my distance between camera and model is more than one meter ... all work good !
Camera must be perpendicular to your model do not have picture distortion ...


/o
o                               <-----------   Webcam
\o

Good for tracking !

if

/o
o
\o                     <------------
                                          \
                                           \
                                             Webcam

that's bad for good tracking ....

more you have distance between Webcam and Model, more you must have Led power (or less Webcam Filter - or a mix of these two suggestions ....   (see tracking point size in cam tab preview ...))
Christos #3 19/03/2009 - 21h13

Class : Apprenti
Posts : 18
Registered on : 18/11/2008

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I use a 9V Battery, 3 SFH 485P LEDs, connected serially and a 60 Ohm (or 70) resistor now, and the maximum distance is about 60-70 centimeters.
I tried in low light but it is the same. According to the the wizard the current is about 70-80 mA which is high! I have a 50 Ohm resistor which will force a 90mA current.
I dont think these make any sense. With a modded cam, it is supposed that 50 mA are more than enough!
Whatever the threshold is, 70 cms is the best I can get off my build...
And the webcam is modded. IR filter removed and negative film in front.
Edited by Christos on 19/03/2009 at 21h15.

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