Successful Computer Vision

[Greg McKaskle]

The latter portion of the white paper discusses setting up the camera so that you are processing good images. Experiment with the WB and exposure and brightness to find a setting that is consistent between your shop and outdoors.

According to wikipedia, an overcast day is 1000 lux, and I believe the lighting for the FIRST field is about somewhere between 85 and 95 foot candles. These are comparable levels of light.

It is also typical for the FIRST field having the lights aiming into the field from each long edge. They do not shine directly into the eyes of the drivers at the joysticks. So the illumination drops off rapidly there.

If you have questions about what a camera setting does, you can look into the WPILib documentation, the Axis documentation, or perhaps ask here.

Greg McKaskle

[Pirate programe]

Question: would this be the sort of tape required for the vision target? I'm not sure of the exact specifications that the vision target requires, so I really need to have this verified.

[~Cory~]

We are attempting to solve the problem by looking at the black rectangle rather than the reflective one. We have pretty good results in most lighting conditions.

[Greg McKaskle]

You should have a piece of the tape in the kit of parts. If you decide to purchase more, I'm almost certain that is the right product.

Greg Mckaskle

[wireties]

What are the LED rings you speak of? Were they in the kit of parts? If not, do you mind sharing the part number?

TIA

[Tom Line]

Go to superbrightleds and look up 60 mm "Angel Eyes".

[~Cory~]

What is the legality of using superbright leds? I can't find anything in the manual. When do the leds become a nuisance to the game and called out by the referees?

Has anyone seen a difference as to tracking the reflective tape vs. the black rectangle? Does anyone think one will be better than the other? Will the stadium lighting effect tracking the black rectangle?

[DominickC]

Originally Posted by SuperNerd256

Will the stadium lighting effect tracking the black rectangle?

That came up between a few of our team members when we were discussing which of the two tapes to track. We are unsure as of yet :/

[SuperS_5]

I suggest trying to use LEDs so that the retroreflective tape is put to good use. The lighting onboard the robot, along with the direction discrimination of the tape will allow you to have the best results. Relying on just the dim colour patterns will probably yield bad results. Comparing the differences between using a light source on the robot, and only ambient light was remarkable. This was tested last year in our fairly bright office.

Either way, you can always use both methods, mounting a light source, and using other patterns for recognition. If you come up with a measure of quality of your vision recognition, your program could automatically choose the best fit. The extra cRIO resources consumed can be limited by using a slightly lower framerate. I believe that we managed to have a few independent algorithms running on the cRIO with minimal performance issues.

[Greg McKaskle]

Can you think of a test that would measure the effectiveness? Can you measure which will fail under different conditions? In reality, there is no perfect way to do this or most other measurements, and that is why various measurement techniques were created. Determining which is appropriate under the circumstances and how to make the evaluation is the valuable skill to learn. If you have data to backup your conclusion, I'd be happy to help you understand the data.

Greg McKaksle

[SuperS_5]

I didn't do most of the vision stuff around here last year. For Lunacy, I got something that worked fairly effectively in various situations, but was only a single algorithm. Unfortunately this is not part of my day job, so time is a very limited resource.

The measure of quality calculation would be limited to each specific implementation. (No golden answer, as you have mentioned.) I was thinking along the lines of using some statistics calculations, but this is nothing more then a thought floating around at the moment.

I can't seem to find my archived code anywhere, but I remember taking the vision example from last year and producing a quality measurement which aid in determining if the targets found are valid. Anything that I do come up with, I will post here on CD.

[Solauj]

Originally Posted by ~Cory~

What is the legality of using superbright leds? I can't find anything in the manual. When do the leds become a nuisance to the game and called out by the referees?

<R08> "Shields, curtains, or any other devices or materials designed or USED to obstruct or limit the vision of any drivers and/or coaches and/or interfere with their ability to safely control their Robot

My team thought one way to get around this was to have a switch that would turn the LEDs off, unless we wanted to shoot a ball. In that case the LEDs would turn on and the camera would orient the shooter.

Using IR LEDs would also get around this, but the tape may not reflect it. Also you would have to remove the IR filter in the camera lens.

[Greg McKaskle]

SuperBrightLEDs is the marketing name for the company, not necessarily a truthful measurement of their brightness. Since they were donated to FIRST, I would assume they are legal on a robot.

As for IR, I suspect most light sources will show up bright in IR, especially tungsten and incandescent. And of course one of the reasons it is hard to know is that you can't see IR, so debugging it may be more frustrating than light you can see. But of course, I don't want to discourage you from the experimentation. Good luck with it.

Greg McKaskle

[gaurav.agashe]

Hi baronep,

I used your first post as a guideline; thank you for that! My vision vi works, but only when I don't have the particle-filtering wired up. As soon as I include it, the cRIO crashes upon "Enabling Vision". Below is a link to a screenshot of the VI generated by vision assistant, that includes the particle filtering block. I pasted this into my Vision Processing VI appropriately. Can you spot any glaring errors in this? Was I supposed to alter this VI in some way before pasting and wiring it into the rest of my code? Thanks!

http://www.chiefdelphi.com/forums/at...4&d=1329489628