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Vector tracking with TrackClip PRO

Posted: Sat Aug 04, 2007 12:54 pm
by ppalmer

I'm using the OptiTrack SDK to track the player's head for 6 DOF in my first-person shooter.

Using the vector cap, this is all starting to work properly.

Naturally I want to support TrackClip PRO. Does OptiTrack provide vector tracking support for TrackClip PRO, or do we have to implement this ourselves?

1. If TrackClip PRO is supported, how do I switch the vector tracking into this mode?

2. If it isn't supported, would someone be willing to share with us the code/maths involved in tracking it manually?

Many thanks,

Re: Vector tracking with TrackClip PRO

Posted: Mon Aug 06, 2007 12:53 pm
by Birch
The TrackClip PRO is not supported in the OptiTrack SDK. Since it does not recognize the different shape and orientation, it cannot track and properly extract the 6DOF information from it. We don't have plans to add support for it right now, but will also keep the feature request in mind.

Re: Vector tracking with TrackClip PRO

Posted: Sat Aug 11, 2007 4:31 pm
by ppalmer
Thanks for the reply I'm now tracking the TrackClip PRO manually and this is working well.

Of course, correctly tracking the clip requires totally accurate measurements. It would be a great help if you could share these with us:

1. The exact 3D measurements of the TrackClip PRO (ie. where the lights are positioned on it);

2. The exact vertical and horizontal field-of-view angles of the TrackIR 4 camera.

Thanks again,

Re: Vector tracking with TrackClip PRO

Posted: Tue Aug 14, 2007 4:01 pm
by Birch
Here are some rough measurements which should work, if you want more precise ones you will need to take them.

1. dist01 = 50mm, dist02 = 94mm, dist12 = 111mm

2. 46 degree horizontal FOV for the TrackIR 4 PRO

Re: Vector tracking with TrackClip PRO

Posted: Wed Aug 15, 2007 5:31 pm
by ppalmer
Thanks very much!

In case it helps anyone else, here are the light coordinates derived from those distances:

0, 11.141, 0

0, 8.4210383269006372857014630643569,

0, 0, 0

Here are the measurements I got for the FOV:

At 50 cm:
X range: 39.5 cm
Y range: 32.7 cm

Degrees horizontal: 43.1080398409576852872964212771
Degrees vertical: 36.21548948455846324572206414806
(I can't bear to throw-away decimal places!)

Thanks for the help,

PS - Would it be ok/good/bad for me to share my TrackClip PRO tracking code once I'm completely happy with it? This would make it easier for other non-commercial projects to make use of the device.

Re: Vector tracking with TrackClip PRO

Posted: Wed Sep 12, 2007 12:28 pm
by pdenbrook
I would also like support for the TrackClip Pro to be added to the OptiTrack SDK. In the meantime, I would very interested in trying out your tracking code, Phil, should you have the opportunity to make it available. (We also have a non-commercial project which uses the TrackIR.)


Re: Vector tracking with TrackClip PRO

Posted: Tue Nov 13, 2007 1:49 pm
by ppalmer
Hi Patty, sorry for the late response - I only just saw your post!

I've dumped the relevant C++ code here:

Although it's actual working code, you'll have to piece it together yourself to make it compile and to make it usable (see readme.txt).

I hope this might be useful for you.

Good luck with your project :)

Re: Vector tracking with TrackClip PRO

Posted: Fri Sep 05, 2008 3:10 pm
by ppalmer
Hi again,
I've greatly improved my unofficial TrackIR support now, so it's clean & accurate, and I'm pleased with it.
I'm using the equations from the paper "3D Pose from 3 Corresponding Points under Weak-Perspective Projection" by T.D. Alter (AIM-1378). I'm also using adaptive smoothing to filter-off pixel jitter without introducing lag on the movements.

All the source code is now included in the game install at (see OptiTrack.cpp).

The style of headtracking in the game makes the screen a 'virtual window' into the game world, and it also enhances stereoscopic modes by cancelling-out the usual problems of screen parallax and head tilt. If the game is played with a head-mounted display, the TrackIR is used for 'VR headset'-style headtracking instead.


Re: Vector tracking with TrackClip PRO

Posted: Sun Sep 07, 2008 2:41 am
by electrikcar
I assume you need a SM3.0 or higher for your neat program (Le Cauchemar) because all I can get on an ATI SM2.0 is a black screen with a crosshair and white diamonds when looking around (representing the light sprites I presume). Can you elaborate on the system requirements?

Re: Vector tracking with TrackClip PRO

Posted: Sun May 03, 2009 7:57 am
by ppalmer
Hi electrikcar, sorry for the late reply.
Shader Model 3 is required to run my demo, but as far as I know that's the only real requirement. I have a feeling the latest version misbehaves on nVidia Quadro cards though.

In December I tested the game's head-tracking using a FLEX:V100 camera and that works nicely. The demo now includes an options profile for that camera.

Given the right settings in the config file, the demo allows OptiTrack equipment to be used for 6 DOF headtracking at the same time as an HMD is used for stereo viewing (native off-axis stereo). This starts to give almost a 'holodeck' experience, letting you pace around on virtual ground, duck behind walls and peek around corners. I've tested this with a Z800 HMD.

If anyone has more questions, feel free to contact me any which way :)