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moving dancer
Martin Hug from Spain  [6 posts]
4 years
Hello.
Id like to capture a dancer in a space of 12m*12m. The camera is mounted in 5m height in the middle of the stage, so that I get a perfect top-view.
I made some experiments with the RGB filter (with a red had) to get a center of gravity and sending the results with OSC to another program. But as the dancer moves fast the center of gravity gets lost quite often and it depends a lot of the light (it will be theater lightning).
Could I use IR LEDs and is there a filter for it? Or is there a better way. It would be nice to get the x-axis, y-axis and if possible a z-axis or a result of mass.
Martin
EDV  [328 posts] 4 years
You could use motion detection for such task:
http://www.youtube.com/watch?v=Rmxb0tE7MIw

Implementation in AVM Navigator:
http://www.youtube.com/watch?v=4uywp5TNrZk#t=92

Output:
NV_OBJECTS_TOTAL - total number of recognized objects
NV_ARR_OBJ_RECT_X - left-top corner X coordinate of recognized object
NV_ARR_OBJ_RECT_Y - left-top corner Y coordinate of recognized object
NV_ARR_OBJ_RECT_W - width of recognized object
NV_ARR_OBJ_RECT_H - height of recognized object
Martin Hug from Spain  [6 posts] 4 years
I can't find the AVM navigator.
Thanks Martin
EDV  [328 posts] 4 years
It's additional module (plugin):
http://www.roborealm.com/help/AVM_Navigator.php
Steven Gentner from United States  [1370 posts] 4 years
Do you have a sample of your video that you can post?

If the red tracking didn't work, perhaps there is another feature that you can use.

STeven.
Martin Hug from Spain  [6 posts] 4 years
1. I can't find a link to download/purchase and install the Plug-In.  The above link points to a page with a lot of examples, but no instruction to install the Plug-In,(or a least I can't see it).


2. No, there is no video it will be a live performance.

Thanks Martin
Steven Gentner from United States  [1370 posts] 4 years
Martin,

If you look on the home page there is a radio button next to the AVM module that you can select and then press the purchase button to purchase it. This assumes you have already purchased RoboRealm (which you have) as the module needs RoboRealm to run.

I'm not convinced that this will be the solution you are looking for. You have to understand that machine vision is very much in its infancy so being able to detect a dancer in all directions an in any position is not yet possible. You typically find a shortcut like using color or motion to work around the need to entirely understand the position of a human in order to track them.

So the questions above are about finding that shortcut ... which if you don't know exactly the environment that the dancer will be performing in this will be next to impossible. You even experienced this with the red filter, change the light and nothing works anymore. There are ways to mitigate this (i.e. lighting) but there are limits. The more you know about the environment that will be used the better the detection will be.

Its probably better to augment this solution with an active sensor like the Kinect. Its built to detect people and even from an overhead shot will nicely show a bump on the floor that can be assumed to be the dancer (assuming a flat floor here). Are you able to position a Kinect to look down on the dancer? Or perhaps you can put two calibrated cameras overhead to be used for stereo?

At least using these kinds of sensors would provide you a solution that assumes the dancer is dancing on a flat surface (again, see, you still need to know the environment). If not, i.e. there are props around the dance,  then perhaps combining depth and movement would solve that issue.

STeven.

Anonymous 4 years
Steven.
Thanks for the detailed answer.  Probably the "simple" color tracking is the way I'm going for as I could create interesting sound simply knowing the dancers x/y position in a space.  
As the ip-camera will be mounted on top of the stage I thought to experiment with a IR-LED cap (20 IR-LEDs), so the dancer could  even be seen also in darkness.
Do you think this could work?

Martin
Steven Gentner from United States  [1370 posts] 4 years
Martin,

The IR camera is worth a shot. What you probably want to do is tape over the little light sensor that switches these types of cameras from regular to IR. This will prevent the camera from switching out of IR mode which would cause the image to radically change.

Can you try this and see how that works? Its possible that without any other IR source that the highest object would be the brightest which combined with movement would probably get a good tracking of the dancer ... tough to know without running a couple experiments. The IR leds are powerful but will diminish in brightness quite quickly so it can be used as a primitive depth sensor ... but if another IR source is active and contributing to the image this fails. (i.e. sunlight)

STeven.
Anonymous 4 years
Ok, this will take a couple of days. I will inform the forum with my, hopefully successful,  IR-LED light source tracking a dancer.
Thanks Martin

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