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Old 06-18-2007, 02:31 PM
ruddle ruddle is offline
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Join Date: Jun 2007
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How to load multiple LEDs into PPT

Hey,

I need to set up a simple VR tracking three LEDs, one on the head and two in both hands. Is there loading sequence I have to follow so that these LEDs can be indentified. The following possibilities are my guess:

1. Turn on all the LEDs before running the script, each light at a different height. And initialize them at the beginning of the script based on height.
2. After starting the script, turn them on one by one, for example, from the one with the highest altitude to the lowest.
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  #2  
Old 06-18-2007, 02:40 PM
mspusch mspusch is offline
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Which version of the PPT are you currently using?
The newer versions allow to select the number of lights tracked in the PPT interface (i.e. select 1-8 lights).

also, are you using a PPTX2 (with 2 cameras) or a PPTX4 (with 4 cameras)?
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Old 06-18-2007, 03:03 PM
ruddle ruddle is offline
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I'm using version 2.17, PPTX4.
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Old 06-20-2007, 12:21 AM
mspusch mspusch is offline
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thanks for this info.
we don't fully understand your question.

with PPTX4, version 2.17, you should be able to select up to 8LEDs in the PPT user interface.

if you select three LEDs, PPT will always search for three LEDs and send their position coordinates. if you have the LED's positions, you can do with this data whatever you want to do.

Please make sure to follow the PPT instructions for setup and calibration, and specifically so the 1-point calibration as described in the manual.

this will give your PPT the info about how you are moving in the space and allow to optimize tracking for your individual movement speeds.

PPT is generally pretty good with holding on to individual LEDs, however the LEDs do not have an individual identification (i.e. from the PPT-s perspective look all the same). Therefore, if you are tracking head and hands and you only use three LEDs, then you will need to introduce certain criteria to distinguish.

Please have a look at thread

http://www.worldviz.com/forum/showthread.php?t=175

for some sample algorithms.

Another option that works quite well is to use two LEDs on a stick with a fixed distance for at least one of the hands.
This allows to distinguish left and right hand even after rotation.

hope that helps.
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