Author Topic: IR results are not stable  (Read 7099 times)

Offline 1ntegr0

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on: January 02, 2012, 01:51:21 PM
Hi

I'm trying to do 3D tracking with my Wiimote, but I have a problem. Got a library working very nicely, it detects LEDs perfectly and passes the locations to my application. Problem is that the devices have A LOT of jitter and variance: if I keep my Wiimote perfectly still, my LED positions go up and down like crazy. it's as af my Wiimote is vibrating all the time, while it's actually lying still on my desk. The movements vary between 1 and 5 pixels in either direction and all LEDs seem to move independently. Because of this, the algorithm that I use in a virtual scene is completely ruined and gives false results!

Has anyone had this problem before? How did you fix it? I trid averaging several frames, seen as the update rate of a Wiimote is very high, but that didn't seem to give me any better results



Offline 1ntegr0

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Reply #1 on: January 02, 2012, 05:21:44 PM
Added a video on youtube to illustrate my problem:

[youtube]http://www.youtube.com/watch?v=jNvJTpM6nGM[/youtube]



Offline boonjin

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Reply #2 on: January 02, 2012, 07:07:26 PM
How are the IR LEDs placed?

How far are the IR LEDs from the Wiimote?

Placing the Wiimote on the table by itself may also cause the Wiimote to move by itself from the vibrations.

Regards,
boon Jin


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Offline 1ntegr0

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Reply #3 on: January 03, 2012, 05:39:10 AM
The IR LEDs are mounted on a cardboard sheet, which was placed on a table. The LEDs cannot move at all, so they can't be causing the movements, especially since all leds move independently

The distance between the Wiimote and the middle LED (the red one in the video) is 80cm, give or take

How can the Wiimote move by itself? The vibrations of the Wiimote have been turned off at all time.



Offline boonjin

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Reply #4 on: January 03, 2012, 08:11:19 AM
The IR LEDs are mounted on a cardboard sheet, which was placed on a table. The LEDs cannot move at all, so they can't be causing the movements, especially since all leds move independently

The distance between the Wiimote and the middle LED (the red one in the video) is 80cm, give or take

How can the Wiimote move by itself? The vibrations of the Wiimote have been turned off at all time.

Any small vibration on the table may cause the Wiimote to move. From the video, it seems to be moving quite a lot. Maybe it is due to the library used which amplified the error.

It is common for the IR LEDs to be detected at around a certain value with deviation of several pixels as the IR LED itself is not a single point but a large blob.

Maybe you want to try to take a look at the IR points, via another library or you may use Smoothboard to see the points.

Regards,
Boon Jin

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Offline 1ntegr0

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Reply #5 on: January 04, 2012, 05:11:05 AM
I did another test: when I keep my Wiimote very close to my LEDs (30cm), only one LED is moving. The movements are also limited to one pixel max, though they are constant and uncontrollable. Could this mean that the distance between my Wiimote and my LED setup is causing this issue? Seems reasonable to me seen as small errors tend to increase with distance.