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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > Step 2: tuning FT, the cam, and the visible light filter

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JayPeeII #1 02/09/2013 - 20h19

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As a result of this topic http://forum.free-track.net/index.php?showtopic=3931&page=1#19291

I am now in the process of tuning the webcam and visible light filter.

What I am experiencing:

If I move my treshold almost all the way to the left, my LEDs are seen pretty well. I have a 1/30s exposure and max (10.000) gain. However, when I move my head, FT sometimes loses track of the LEDs for a very brief moment but enough to have my virtual head stutter. When I stop moving it picks up the LEDs again immediately. The faster I move, the higher the chance it loses track during movement.

What could cause this? Filter too strong? Webcam settings not adjusted well enough? RGB24 vs I420?

I'm using 5 layers of photo 'negatives'. Take note, this is not the same as a fully exposed film roll you normally put in a camera. 'Negatives' are like the blue print you need if you want to make another copy of the photo. It's what you get from your photo production shop after your film roll has been developed into photos.

Again, thanks for helping me out. Especially Steph and Stormrider for constantly updating me in my previous topic.
Steph #2 03/09/2013 - 07h07

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Try out several daylight filter solutions.
It has to be just enough to block visible part of daylight that's all.
It can be a little bit tricky to find a good compromise but allows you to decrease exposure and threshold.

Other filter solutions:

Scotch like this:

Posted Image

Multiple layers off coloured plastic sheets.

Posted Image

Some remote controls or older electrical equipment got real daylight filter in the front-plate to cover the IR-receiver diode. I do recover one on an old VHS-recorder. It works really good.
Edited by Steph on 03/09/2013 at 07h08.
JayPeeII #3 03/09/2013 - 15h36

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I'm working on the filter as we speak.

However, I cite the Software FAQ

View panning stutters.

It is important to ensure that the setting Global -> Interpolation -> Average webcam fps is set to the actual webcam frame rate reported in the Cam section.

Make sure Jitter isn't too high and FreeTrack is minimized. When FreeTrack is not minimized the webcam frame rate is not controlled so some stuttering is to be expected.



Under "Global" there is no such thing or category as interpolation, nor can I give in webcam FPS else than at the "Frame Rate" tab under "Cam".
Edited by JayPeeII on 03/09/2013 at 15h37.
Steph #4 03/09/2013 - 16h53

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Handbook is from Freetrack 2.1.
Now you find this settings under -->Cam --> Framerate.

It means that you have to set up the same framerate like in the -->Cam -->Stream section
Posted Image
Posted Image

Here are my settings, that are probably identical to yours, as I use a Quickcam 5000Pro.

Posted Image
Posted Image
Posted Image

As you can see I do decrease exposure and gain.
JayPeeII #5 03/09/2013 - 18h04

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Pray it doesn't change, but I got stable tracking with no stutters and constant 30FPS!

No I'm going to toy around with the FT settings. I'll report back when I have trouble configuring. Currently my cam is aimed upwards as its about 30cm below the left and right LED on my cap so I have some corrections to do.
Stormrider #6 03/09/2013 - 20h32

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have fun :D
JayPee #7 03/09/2013 - 21h13

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Well, seems I have to ask for help again...

This is my situation (notebook simmer):
Posted Image

The green line is about 60cm to 65cm, the blue line is about 25cm to 30cm. Should I change anything besides the dimensions of the LED model itself to match the actual set up?

I have a feeling the height difference between the cap and the cam is causing
- RL head yaw: virtual head yaw + pitch down
- RL head pitch down: virtual head limited pitch down
- RL head pitch up: virtual head limited pitch up
- RL head roll: virtual head roll + yaw

Using tangens to calculate, the angle between the green line and the cam's centre line of sight is rhougly 24 degrees. So I would think I have to set pitch to +24 degrees. However, my cam is tilted upwards to look straight at my LEDs, do I still need to set pitch +24 deg. or does that only apply when the camera would be horizontally placed and looking along the green line?
Edited by JayPee on 04/09/2013 at 10h18.
Stormrider #8 08/09/2013 - 18h26

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I think the first thing I would try to do, is put your webcam on a higher place.
If you move your head up, do you still have three green dots?? :huh:
I think because of the height difference, if you move your head up the middle led will be less visible.

Maybe you can try to place your webcam higher and see what happens.
Keep an eye on the green dots in the bottom right corner of freetrack.For good tracking you must keep all the time three green dots.
JayPee #9 12/09/2013 - 13h31

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Will placing the reference point LED 10cm in front instead of back be a workaround for this problem?

Frankly, this is how my laptop is set up, and I don't have the means to change it since it don't feel like making all kinds of odd constructions to get the cam placed 30cm higher.

Btw, I continuously have 3 green dots this way, even when pitching up. However, read my previous post on the effects I'm experiencing right now (yaw gives pitch, roll gives yaw, etc.)
Edited by JayPee on 12/09/2013 at 13h33.
Stormrider #10 13/09/2013 - 09h42

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Will placing the reference point LED 10cm in front instead of back be a workaround for this problem?


If you keep having three green dots there is no need to change someting in your set-up.

I have a feeling the height difference between the cap and the cam is causing
- RL head yaw: virtual head yaw + pitch down
- RL head pitch down: virtual head limited pitch down
- RL head pitch up: virtual head limited pitch up
- RL head roll: virtual head roll + yaw



Your problem is caused by settings in freetrack.I think if you read this post it may will help you (I hope).Especially the part about the deadzone.
http://forum.free-track.net/index.php?showtopic=3669&page=1#18665

If yaw is pitch you can also change it.
At the profile tab go to advanced and then take a look settings.There you can change for example yaw for pitch and so on.But I don't think you have to change there something.Because as I understand you move your head and it makes two movements.
Posted Image


So I would think I have to set pitch to +24 degrees



My cam is looking down on me, I just kept it on zero degrees without any problems.So if you have to change it to 24, I don't think so but I don't know for sure.

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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > Step 2: tuning FT, the cam, and the visible light filter

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