Concerns regarding the green paneling/green shirts

[Steve Howland]

I don't think it will really be a problem in most cases:

Assume your robot is programmed to begin looking for green as soon as the match starts. To avoid robots running into one another, the bot looking for the tetra (decided upon by the alliance) would probably be in the "B" position (the one a little forward). It would somehow do a sweep of the field looking for green in a few quick seconds, and once it saw something green it would move towards it. For an ally to be the target, it would have to race out and get in the way of the green-sensing robot before it found either vision tetra. For an opponent to be the target, it would need to race across the field and be noticed by the robot before either tetra was seen, which would be pretty tough and clearly the only reason to do that would be interference, which the judges would notice and then penalize the team.

[scottm87]

The vision system has a few different modes. One mode (that most directly applies to the challenge) returns the location and bounding boxes of blobs of color. In the code, it most likely takes these bounding boxes, sorts them by the similarity to the target color, and plots a path depending on the blob's X position or something. It would not be difficult to A) decrease the range of colors or B) apply another level of filtering to determine the height of the blob off the playing field to filter out humans or robots (tall ones at least).

All I am waiting for is someone to pick up a serial CompactFlash interface that are always in Circuit Cellar, and write the frame captures and show a post-match movie .

[Greg Marra]

Regarding using the camera to find the loading stations and/or goals:

You know exactly where these are. The camera would be less important in locating them then it would be the vision tetras. If this new scripting language works as well as it looks like it does, you can very easily dead reckon to exactly where you want to be, sans camera.

[Josh_VK]

This does seem like a large problem. Our Team 773 The Kingsville Kukes have always been green we use green to promote our local Green Houses. this is a large role in our funding. I don't see First telling us we cant use green on our robot. Also are they specifying a paint that the tetras will be done in. it would be a shame to program for weeks to a specific shade of blue and have it not work at competition.

[Jeffrafa]

why don't you go work with the vision system some before you go needlessly arguing over green robots, green shirts, and other distractions. IF in the process of trying to make it work you find that it is easily thrown off, then come here to ask questions about how to correct this problem in detection.

Its something any of us interested in vision will half to test, but just ranting back and fourth about all the possibilities of false detection without ever trying the system is a huge waste of time.

Personally, my guess is the focal range of the camera won't be entirely too large, probably green robots on the other side of the field won't be a problem, and defenitely a crowd in the background won't matter, but i'm anxious to work with the vision system before i commit to saying this is the case.

But i urge you - go try something with it before you sit here on chiefdelphi and needlessly banter back and fourth over it, without experience with the device you have no way of knowing, but by working with it some you can learn an awful lot.

[Rickertsen2]

I Have done some experimentation with the CMU cam and this may very well be a problem with primitive code implementations such as the one provided by FIRST. In order to set the sensors to work reliably in a broad range of light conditions it is necessary to make the tracked color range somewhat large. I have seen some team T-Shirts that pretty closely match the vision tetra colors. The good news is that there are some simple (well relatively) techniques to prevent this by mounting/aiming the camera properly and having a good understanding of the camera's virtual window settings, noise filter settings and how to use them. I feel that FIRST has already babied everyone enough so i am not goign to hold your hand and write your code for you, but i will help with any questions.

[Al Skierkiewicz]

Originally Posted by scottm87

The vision system has a few different modes. One mode (that most directly applies to the challenge) returns the location and bounding boxes of blobs of color. In the code, it most likely takes these bounding boxes, sorts them by the similarity to the target color, and plots a path depending on the blob's X position or something. It would not be difficult to A) decrease the range of colors or B) apply another level of filtering to determine the height of the blob off the playing field to filter out humans or robots (tall ones at least).

All I am waiting for is someone to pick up a serial CompactFlash interface that are always in Circuit Cellar, and write the frame captures and show a post-match movie .

I think Scott and a few others are on to something here. The sensor is a camera capable of color matching and shape matching. It is not just a color sensor. I think we are blowing this out of proportion. Thunder chickens, don't change your shirt color and other teams don't worry about your robot color and MCs don't go for black shirts until we get some real data about the software and the camera. There are some pretty cool and knowledgeable people at IFI and FIRST, don't you think they would have thought of the problems.

[Gary C]

i wonder how the sensor would work if a competition was held at chatsworth high school all the lights are ORANGE!!!! hahahahahahah

[unapiedra]

Originally Posted by Jay H 237

There is no rule against painting or anodizing your robot green (or any other color for that matter).

[EDIT] What I'm referring to per the rule is there's no rule against having a green bot to start with. You just can't change it's color from match to match.

To what rule are you refering to regarding you can start but cannot change to the green color?

[Kyle]

Originally Posted by unapiedra

To what rule are you refering to regarding you can start but cannot change to the green color?

rule R26 in section 5 page 11 it says " No devices are permitted on the robot that are intended to jam or interfere with the operation of the vision system
( i.e changing robot color to confuse opponent's vision system."

[JBotAlan]

Originally Posted by Kyle

rule R26 in section 5 page 11 it says " No devices are permitted on the robot that are intended to jam or interfere with the operation of the vision system
( i.e changing robot color to confuse opponent's vision system."

As much as I understand your argument, I think it would just be safer to not use any green paint this year. I would hate to get to inspection and have them tell me that I can't put the 'bot on the field because it's green. Everyone will be trying to get their green 'bots through inspection saying that their team colors include green. It would be good to not be at the mercy of the judges.

[dlavery]

A few items that you might want to consider before you go heading down too many blind alleys:

- There are three possible starting locations for your robot. Pick any of the three. You know what the field should look like from that vantage point.

- There are eight possible starting locations for the vision tetras. Those locations relative to the robot starting locations are known and fixed.

- The number of robot location/vision tetra position permutations is finite.

- The CMUcamII allows you to trim the field of view to a pre-defined area of the video frame, so extraneous items that are not of interest (ie. off-field items) can be ignored.

- For a given field of view, if two or more objects of the target color are in view and the CMUcamII is requested to locate the target, it will return the location (in X-Y coordinates within the frame) of the largest color blob of the desired color.

- For a set of given obejcts of the same size, closer objects will appear larger (duh!)

So you really have only one question to ask: can you use the camera to look from a given point toward another given point, and determine if the second point is occupied by a certain known object or not?

-dave

[Petey]

Thanks, Dave. I'm fairly sure I understood some fraction of that.

I'm not sure if it completely solves the problem, but it provides some direction, at least. Although - For a given field of view, if two or more objects of the target color are in view and the CMUcamII is requested to locate the target, it will return the location (in X-Y coordinates within the frame) of the largest color blob of the desired color. scares me.

I'll forward this on over to the controls people.

I'm still waiting on the "official answer" from the FRC Q&A forum, for anyone who is breathlessly awaiting it.

[elknise]

During our Kickoff meeting, we brought this up. The CMUcamI, which we used in a different competition last year to track a orange cone, could pick it up at around 30-45 feet depending on lighting, so, this being CMUcamII, it would imply that it might have a longer range. One solution to just finding the colors on the field would be to mount it low to the ground and to angle it forwards, to limit the distractions it can recieve from its sorroundings.

Edit: During the competition, one of the other robots did chase someone from the crowd who was wearing a brightly colored red shirt when it was going for a orange cone.

[shotgunking777]

hey what if you made a robot to throw out like a green flag into the field
ha think about that but don't steal it.....