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Hello.

I have a big question about camera setups. If this information is listed clearly somewhere and somehow I have failed to find it I would be very grateful if you could point me in the right direction.

I know the standard camera setups presented on : http://www.naturalpoint.com/optitrack/p ... n-capture/.

What I am interested in is setting up a non standard volume for getting the most out of a small space.


I understand that in all camera setups all cameras have to point towards the center of the capture space ( they can be slightly off, but not by much), and also they should not " see" each other directly. This limitation is caused by the fact that each camera has an active source of IR light.

I understand that forinstance the most common set-up for 12 cameras is : cameras being placed on vertical tripods, on a hexagon. For instance on a six meter diameter hexagon, if one were to place two cameras on each tripod (one mid-height and one at the top) one would get a capture volume of about two by two meters in the center, and at most 2 meter height. ( The capture height is never specified inthe provided schematics.)


It seems to me that if "cameras not seeing one another" limitation could be somehow mitigated, then by simply adding more R2 cameras to a a small available volume (using 24 instead of 12 on a 4/5 meter area and 2.5 meter height, BUT with ACTIVE markers and the camera's own light source turned off) the setup could produce a maximized capture volume.. Am I correct in making this assumption ?


I mean ,if IR light source from the camera is completely shut off, and the suits are all built with active markers ( IR LED's) would it be possible to set 24 cameras in a small space (4/5 meter area and 2.5 meter height)with a placement different from the standard ones to make much more use of the space then using passive markers.

The use of passive or active markers aren't going to effect the actual capture volume of the setup. Part of that is limited to the camera view itself, and the FOV of the lenses.

Also using Active markers can also be a little limiting, as the light being directed out of the LED itself is directional, where the passive markers allow for a more spherical IR source, from multiply angles.

Generally recommend setting the upper cameras at 2.6 meters -> 3.3 meters, with the lower cameras .6 ->.8 meters below them.

With the new 3-marker camera calibration released this year the camera overlap requirement has been eased up. You'll still need some overlap between cameras to calibrate and ensure coverage of the same markers from different angles (especially if you're using a lower camera count), but you have more freedom to experiment and optimize your volume.

Thank you Vincent. So the only limiting issue is the camera FOV ? So there is not a limiting issue with cameras seeing or not seeing each other?


I mean for instance, if instead of using a hexagon layout with a 6 meter diameter (6 tripods x 2 cameras=12 cameras) I were to use twice as many cameras on a smaller area, (12 tripods x 2 cameras= 24 cameras) but a a smaller diameter (5 or 4 meter) circle, would I get roughly the same capture volume as I did on a 6 meter hexagon with 12 cameras due to the higher redundancy ?

setup area is going to be a big factor in the actual capture area. When using a smaller setup area the capture volume will be smaller, although it can be possible to increase the usable portion of the capture volume with more camera coverage. Using more cameras without trying to increase the capture volume size will typically allow you to get better camera coverage and reduce marker occlusion.

Understood.
A 12 camera setup, using 6 tripods on 20' circular shape would yeld a 10' circular capture volume, with a height of about 6'12" meters, or that is what I understand from the diagrams presented on the site. Is that correct ?

Is there any way to estimate how large would the usable capture volume would be (floor radius and height) if doing the same as above, but with 24 cameras instead of 12 ,(12 tripods instead of 6) placed on 16' circular shape?


At this time we are considering going with.
http://www.naturalpoint.com/optitrack/p ... undation24

I would also imagine that aside the bundle we should add the motion capture suits (at least 2) and marker sets (at least 2).

The tripods and joints will probably order locally as it makes little sense of having that shipped overseas.

Are there any other materials typically purchased with a mocap bundle? (I am especially interested if there are parts that tend to wear out over the course of a year or two and might need periodic servicing or replacing.)

Conservatively speaking a 16' setup is going to give you an 8' capture circle, you may get a 1-2' incease using wide angle lenses