Vision: Object Identification

[omalleyj]

Originally Posted by Greg McKaskle

There should be a vision white paper on the NI site later today, and it is currently on FIRSTFORGE in the documents section.
Greg McKaskle

Greg, Which documents section? I have access looked in the 2012 Beta and Community projects and didn't see it.
EDIT: Never mind, it is on the NI site now, I did not hit refresh :-/

Thanks

BTW, we did not have issues in either Lunacy or Breakaway using vision, though the (Java libraries were a bit behind C++ IIRC). Most of the time I saw people trying to use too high a resolution and too high of a frame rate. 320x240 and 10FPS was plenty and did not bog things down.

[Greg McKaskle]

I agree that it is better to run the camera resolution and framerate at values needed to control the robot, and not much higher. The paper does a little analysis of the distance where the targets cannot be processed for a given resolution. It doesn't do anything with rate, but this year, I suspect it will be most common for both target and robot to be stationary in most situations.

Greg McKaskle

[baronep]

What color of LEDs should one use? I believe IR was used in the vision example from last year.

[Greg McKaskle]

The white paper last year used a string of indoor LED Christmas lights inserted into foam. They were red LEDs. This year, the paper points out some products from SuperBrightLEDs.com, which, while designed for cosmetic purposes, work quite well as ring lights. I've tested green, red, amber, and blue. All colors can be made to work provided you get the white-balance and exposure settings such that the reflected colors are very saturated.

If you choose to avoid the color masking and simply go with a brightness threshold to form the mask, it doesn't matter what color you use, and you can even mix colors or use a white light. The LV example vision code for 2012 shows both color and brightness approaches. For brightness, it also sets the camera to disable color, receiving a monochrome image directly from the camera.

Greg McKaskle