Turrets and cameras

[Alexa Stott]

Originally Posted by spc295

would it be against the rules to mount a large colored light (not pink or green) to manually aim a turret. this would avoid camera problems, as well as help the driver aim the turret. that way you can see if you are illuminating a trailer or not?

If you can find a way of doing this without impeding the vision of other drivers, I'd say go ahead. We fooled around with this idea a bit in 07. We thought about illuminatig the spider leg with another color and tracking that, but were unable to find a light source appropriate for it.

[Greg McKaskle]

The corrected images were taken after dropping brightness and lowering saturation.

Greg McKaskle

[Tom Line]

We have absolutely horrible lighting in our workshop - it's flourescent tubes every 3 or four feet. Our camera always points upwards and is mounted in a fixed orientation.

The best procedure we have come up with for camera tuning in labview goes like this:

1. Enable HSL debugging in the Find Two colors VI.
2. Enable HSL coloring in the Vision VI.
3. Hover your mouse over different parts of the greent target. Try to hover it over a dark patch of green and a bright patch of green. Watch your initial HSL values from the HSL debugging window. Note the maximum for each value, and the minimum.
4. Return to the Vision window and input them on the front panel VI.
5. Turn off the "find pink first" checkbox and look at the mask. More than likely, you'll see a bunch of noise and your two colors. One of the colors (usually the green color) will be flickering. You also may see a bunch of noise.
6. Make sure you're happy with the framerate before going any further. We're happy if we're seeing 15-20 FPS. We go into the Vision VI and set our framerate maximum to below the lowest number we see (with our tracking code, we very much want consistent values).
7. Return to the vision VI. Methodically adjust your green values up and down by 5 at a time. Return periodically to the HSL debugging window to verify none of your values there have changed.
8. Once your green locks in, go back to pink and adjust the values a bit. At this point you should have a reasonably clean mask, with little noise, and two solid shapes.
9. If you are still having problems, or if you aren't getting solid shapes, repeat the process. If you still don't have any success, we've several times resorted to modifying the area and particle settings to make them somewhat more forgiving.
10. Now you need to turn the robot so the lighting changes and repeat. If you're getting a lot of washout, or the color values you're getting between light / dark patches on the target are significantly different, you may need to raise or lower brightness to repeat. It usually takes us 10 minutes or so to get nice solid values that work over most of the area (we've done this in 3 or 4 significantly different lighting conditions just to practice - bright sunlight, flourescent tubes, and incandescent bulbs).

This has worked pretty well for us in several different very poor environments. I hope it helps you guys.

Team 1718

[JesseK]

Greg, this is great information. We'll definitely spend a lot of time in Florida figuring this stuff out, as our shooter is the last thing we have to fine tune.

Our setup: we mounted our camera up as high as possible on our bot; the lens is roughly 55" off the floor. We do not tilt the gimbal; instead it pans to three set locations left, center, and right. We'll add a glare shield to the upper portion of the protective lexan cover we made, and bring back some settings & results from Florida next week. Too bad we can't get the camera feed back to the laptop during the matches -- I'd love to FRAPS it so other teams can see what we tried that may or may not work so they can further perfect the whole system.

[JesseK]

Originally Posted by Alexa Stott

If you can find a way of doing this without impeding the vision of other drivers, I'd say go ahead. We fooled around with this idea a bit in 07. We thought about illuminatig the spider leg with another color and tracking that, but were unable to find a light source appropriate for it.

You could have tried IR LEDs, though be warned that you'll get alot of false positives if other teams do it as well. It'd be sweet because in 2007, a perfect circular reflection combined with open source COTS pattern recognition software would have eliminated the need for a color camera altogether. Tell the software to line up with a reflection, then get closer until the circle had the proper diameter. If only the IFI controller could have handled all of that processing, we might have tried it.

All of the other years, I don't know what benefit there would have been for doing this though.

[Luke Pike]

I have been able to get the camera working pretty well in two locations by adjusting the brightness.

At our playing field there are long fluorescent lights attached directly to the white ceiling. As you can imagine, this lighting is very bad, it causes whatever is in the foreground to bleed into the ceiling where a light is. However, I was able to get it working by setting the camera's brightness to 25. It was here that we shot our promotional video.

At our shop, there isn't as much light, so a brightness of 30 works well. Towards the end of build season I would work all day in the shop and around 3:00 PM the sunlight would shine through a window and blind the camera. A piece of cardboard over the window was enough to get it working again, but once the sun was low enough, the light was to low and I would have to take the cardboard off to make the camera work again! In other words, variable light is bad for the camera.

Good luck to all teams with their camera calibration!