track rigid body

[pvdkrogt]

Hi we just got our Optitrack with 3 OptiTrack FLEX:V100R2-FS cameras,

we now want to track a HMD,

what is best, just 3 markers or more?
on top of the head?

camera position; what is recomended, a triangle or three in a row with an angle? (which distance between?

we want to be able to move arround in an area of 2x4m

[VincentG]

With you looking to move around, I would go with the cameras mounted 8 feethigh, triangle shape. 6meter*8meter setup area, but for that large of a capture volume 3 cameras will be tight.

4+ markers would be better

[pvdkrogt]

Thanks!

We build a 5point marker and placed it on to of the HMD (so it is visible) we used the small round markers that came with the our 3-camera set, but it does loose tracking when turning

any hints?

regards

[VincentG]

Are the points being lost out of the camera view itself? Try mounting a little higher, to give more of a downward angle for the cameras to work with, or add more cameras.

[pvdkrogt]

what happens is that in some occasions we see 5 points in 2 cameras but 3 or 4 in 1 camera

[VincentG]

If it is only loosing one marker, it should still be able to track the rigid body object.

[travisj]

I work in a lab that has implemented just what you are describing. In our old building we had 20 foot ceilings and mounted cameras at about 16 feet, using 8 cameras. however, we could probably have done just fine with 4 at that distance.

we are now in a facility with only 12 foot ceilings and what a difference it is.

here are a few things we have done to track an HMD, maybe it could help with your problem

- we used 4 markers, all on a flat plane (we are looking to try non-planar rigid body shortly)
- the markers are mounted to the hmd, and are on rods that extend 3 inches above a users head to reduce occlusion
- as vincent mentioned, you want the cameras to be high. and as high as you can get them so they are pointed down and can see a large volume of space

not sure of your application, but in ours we have a bluescreen that goes around our capture volume, which creates all kinds of fun situations for us to overcome, and we also incorporate DMX lighting. this makes it more important for us to check our exposure and threshold settings on each camera. perhaps thats something that could cause the drop outs for you

good luck!

[pvdkrogt]

Hi,

we are now trying to build a trackable area of
1)1.5x 3.5 meters and
2) 1m x 11.5 meters

the HMD will move around at a height between 1 and 2 meters

how much cameras and setup will be best?

Regards

[VincentG]

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