8 Camera setup: height of lower cameras? Pointing?

[tvining]

The setups for the cameras don't have height dimensions, so I was wondering, for 8 cameras set in 4 places in an 18' circle with the upper cameras at 7.5', what height should the lower cameras be set at?

Also, when pointing the cameras, should the upper and lower cameras be pointing to cover about the same area so that all cameras overlap for the whole figure at all times, or can the upper cameras be set to look a little high, and the lower cameras look a little low? In other words, can the upper cameras sometimes lose the feet, and the lower cameras sometimes lose the head and still get clean capture, or should each camera try to see the whole figure at all times?

Thanks--Tim

[VincentG]

I would mount the lower cameras at about 5'6", and rotate them 90 degrees.

As far as aiming goes, I would set a single marker, in the middle of the capture volume (waist high), and aim all the cameras at that one point. You want to try and get the cameras to see the tracking object all of the time.

[Jim]

Hello:

If you can get the upper cameras to be at 8', it will help, height is your friend.

You can have the upper cameras more towards the head, and the lower cameras more towards the toes, but you do want a healthy level of overlap, 50% minimum. You can play with the positions and see how the calibration comes out, if it is good, then you are probably okay, if not, then probably not enough overlap.

[tvining]

Thanks! Unfortunately 7.5' is all I have for the space I'm working in. I'll try it with the overlap--I was planning to just cheat them a little high/low to give me a little more play with the hight since I know I'm not at optimal hight or distance. I'll let you know how it works out.

Thanks again--Tim

[artoo]

i only use 6 cams, but think of getting some more..

should the lower cameras not be as low as possible ?
(like 5-10 inch)

[Jim]

It could be a good idea to place the lower cameras at the floor level, looking up, but the camera calibration will not work well for this type of arrangement.

The cameras need to have 50% or more overlap in their field of view in order to calibrate properly. Of course, you can experiment with the camera placements, and maybe some good new arrangement will come out of that.

[digitizer]

Hey Tim,

How did your capture go? Did you manage to get good results at 7.5'?

(I'm facing the same height issues as well...)

[tvining]

Hey Digitzer,

I'm still learning the system, but overall I think the captures show promise. For a standing/walking figure, I think the 7.5 height is fine, but I think I may need to lower my lower cameras for certain shots. I was trying to capture a sitting figure, and I kept losing the front hip marker, so I am going to try to lower my lower cameras (that are at about 5.5) to get a better shot at it.

In general, the system seems to do a better job at a figure that is moving than one that is standing/sitting still, so I'm finding that I do more cleanup for small motions than large ones since with a larger motion, the system fills in the short gaps, but small motions can sometimes occlude a marker for longer, so that needs manual cleanup.

[elbundi]

why would you rotate the lower cameras 90 degrees?
we're using the 8 camera setup and having difficulty getting good capture space.
the lower cameras see each other

[VincentG]

The cameras can be rotated to help with vertical capture in the smaller volumes. As the cameras have a resolution of 640*480.

How do you have your upper and lower cameras setup?

Height?