maximizing capture volume by using only 1 marker

[dgraham]

Hi,

I'm very close to deciding if I want to buy the 3 camera rigid body toolkit package. I only need to track 1 marker. Basically, I just want to track the position of a single marker in the maximum capture volume I can with 3 cameras (preferably more length by width area, not much height is needed). I'm not doing any motion capture, just want the realtime xyz position of a single marker.

So, because I only want to track 1 marker, can I capture in a larger capture volume....the xyz position of a single marker in a 15'x15'x6' ft capture volume? (I have plenty of space in my warehouse to setup the cameras)

Thanks,
David

[VincentG]

And that would be the capture volume, not the setup volume correct?

What size marker are you looking at using?

[dgraham]

Yes,

I want to maximize the capture volume. 15'x15'x6' would be a suitable capture volume, but more would be even better. I have plenty of room to setup the camera, so I have plenty of 'setup' room to work with, but what can I do to maximize the capture volume? I only need to track one marker. As I understand it, you guys supply the markers right? I did not know that we could use different markers? But if there is a better, or bigger marker that would help increase capture volume, then that's great.

Basically, what I want to do is attach a stick to someone's back, and put the marker at the top of the stick, so it appears above the subject's head, and will never be obstructed by the person's body (even if the person kneels down). Then I only want to track that one marker's xyz position. So essentially, I know where the person is and can send the xyz to a game engine. This subject will also be wearing VR goggles to track head movements, so I have no nead for 'motion tracking', just location tracking of the single marker.

So, what max capture volume do you estimate 3 cameras and 1 single marker (no risk of marker confusion, etc) can achieve?

[dgraham]

Vincent? did you read my post? I'm ready to buy, I just need the question in the above post answered.

Please help.

Regards,
David

[VincentG]

The cameras currently have a maximium setup area of approx. 20ft., so the camera range is going to be a limiting factor, along with the calibration needing the cameras to point toward the center.

The 15 x 15 volume may be difficult achieve. It might be a little easier since you won't have to deal with occlusion. Perhaps you could put your cameras in a ring, higher up and angle them pointing further down than we would normally recommend. This could stretch the capture volume size a little. Keep in mind that the cameras would all still need to be aimed toward the same central region of the capture volume in order for the calibration to succeed. But, you will need more than 3 cameras to do this right (if possible). Unlikely with 4 cameras, 8 would increase the chances.

[esslaee]

Hi grahamchilla,

I was able to achieve your specs 15'x15'x6' using 6 cameras. The cameras are setup such that they form a slight arc facing a common point. Oh, and one of the cameras is placed on top of another one, so it looks like ..:..

I made some figures using 3 cameras and 6 cameras (units are in meters) (copy link then paste into address bar; don't click):

3 camera ring setup:
http://img.waffleimages.com/d9ae98de3fa ... 20area.PNG
6 cameras spaced 1.5m apart:
http://img.waffleimages.com/f82015f50d5 ... apart).PNG
6 cameras spaced 2.0m apart:
http://img.waffleimages.com/18b1f43f208 ... apart).PNG

As you can see, THEORETICALLY you can achieve more than 15'x15' base area with 3 cameras. I haven't tried it myself, but it looks very doable. I am currently using the 1.5m spacing of 6 cameras with one on top of the rest.