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Projection tracking - Tracking multiple people

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Projection tracking - Tracking multiple people

Postby et395 » Mon Aug 06, 2018 8:08 pm

I would like to ask for advice on a project I am working on.
The system I would like to build should be able to track the actors on stage from above, while the projector shoots contents on the floor triggered by the passage of the actors. The content should follow the actors, while they are moving on stage.

I figured out the system should have a camera that points to the floor, positioned next to the projector.

I am trying to understand if the system would need a simple camera, or an infra-red camera or a Kinect. If I need to define IDs for each actor and what is a solid approach to trigger the passage of each of them.

With regard to TD, I would love to hear what's the experience with Blob Track TOP and motionSense from the Palette.

I would appreciate if you could address me to any good resources and if you want to share your experience.

Thanks everyone.

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Re: Projection tracking - Tracking multiple people

Postby bnRockwell » Tue Aug 07, 2018 4:09 pm

I can't answer all of what you're asking but I have a few questions/suggestions:

How important is tracking which actor is under a camera? In general, this would be very difficult if the actors do not stay in a particular zone, though there are a few potential solutions for tracking them uniquely across all spaces. If you can, keep it to one camera per person or design the projections such that position is all that matters, not necessarily 'who' its tracking. You could also fake it to some extent if you have someone operating your rig.

A regular or ir camera might work in this case but you'd probably be safer using a depth feed. In the end, you'll want to use something like blob tracking/cv and/or difference the image with a calibrated background texture to determine where in the frame the movement is. From there, you'll have to convert the camera coordinates to the ones your projection uses.

Hope that helps. I've seen a few posts on the forum with projection mapping + kinects that may be of use, so try doing some searches around that. I'd consider how much needs to be done programmatically vs by an operator. You could achieve a similar result with significantly less effort if you create an interface for someone to cue and place the projections during a show.
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Re: Projection tracking - Tracking multiple people

Postby kanelau » Wed Aug 08, 2018 12:36 am

This actually is a tricky one when comes to stable ID. for optical tracking, if you’re good on budget the BlackTrax system is the best solution:


You could try RF Locationing system called UWB,which also requires the actors to wear a device but provide a accuracy of centimeters.

Kinect based systems would certainly work but it’s hard to use multiple devices at the same time while the delay is some kind of big considering on a stage.

Hope this helps.
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