pic: Three Trackballs?

[Matt H.]

Having seen the field first hand I will say that the reflections are quite bad--At times our drive team thought that an alliance was fielding four robots and it can be quite disconcerting to see two of your robot racing down the lane. It seems that the drivers stations are in the perfect position for these reflections as when acting as robocoach I experienced no problems and the audience doesn't see them.

[mtaman02]

Now the real question is

Do you think FIRST and the GDC did this on purpose? Or is this just as unexpected to FIRST as it is to the people who have to drive the robots ?

[GaryVoshol]

I think it's an unintended consequence. It varies from arena to arena, depending on the lighting conditions. Wherever the prototype field was set up, it may not have been so bad.

[Roger]

It's a variant of Pepper's Ghost, a simple trick developed by Henry Dircks in 1862. If you've gone to Disney's Haunted Mansion you saw it in the huge Ballroom scene.

BTW I remember seeing photos somewhere on CD showing this effect on the field and how robots vanish.

[Joe Matt]

I hate to pimp, but we talk about this a bit in the latest episode of FIRSTcast...

http://www.chiefdelphi.com/forums/sh...ad.php?t=65621

[Phyrxes]

Originally Posted by Roger

It's a variant of Pepper's Ghost, a simple trick developed by Henry Dircks in 1862. If you've gone to Disney's Haunted Mansion you saw it in the huge Ballroom scene.

BTW I remember seeing photos somewhere on CD showing this effect on the field and how robots vanish.

Here is the thread with the pictures.
http://www.chiefdelphi.com/forums/sh...5&postcount=52

[Roger]

Thanks Phyrxes. Gosh, no wonder I couldn't find it -- wrong thread name, wrong poster. It's a wonder I can find my way out of bed in the morning...

Looking at those photos again I wonder why they even have those upper panels. The bottom ones I could see, if only for sonar and to match the outside walls. Come to think of it, the outside outside "protector" walls (if you follow me) don't have the panels. Wouldn't it be easier to make a rule "no robots can go thru the wall"? Well, it makes for good post-season rule changes.

[mtaman02]

actually all sides should have panels - outside walls and the divider (basically everything in the center of the field both inside and out have panels... I think...

whats sad is I put this field together and I can't remember for the life of me if there was a side w/o them. A sign of old age :-p and too many field put together.

[EricH]

Originally Posted by mtaman02

actually all sides should have panels - outside walls and the divider (basically everything in the center of the field both inside and out have panels... I think...

whats sad is I put this field together and I can't remember for the life of me if there was a side w/o them. A sign of old age :-p and too many field put together.

2003...Oh wait, this is 2008.

Every side has panels. Two have diamond-plate and Lexan panels, four have chain-link panels (this year), and the remaining ones have Lexan on pipes. Even the gates have panels; those are just easily movable by a human.

[Phyrxes]

I could have sworn the field at VCU did not have polycarb on the pipes making up the outside perimeter (at least on the side nearest the stands).

[Roger]

Now you guys have got me wondering. A quick search found me this photo which may exhibit my thinking.

The ends of the field where the drivers are have the big lexan panels. The angled corners are the chainlink fence. The center divider are 3 high lexan panels. The low outside sidewalls have lexan, but the outer outside walls are just the metal pipe - no lexan. At least I can't see any. There are no zip-ties holding the panels anyway, like the center divider wall has. I remember at the end of Final matches before the awards they were taking the pipes down on the audience side but no lexan.

I realize there is a need for a protector/divider both at center divider and the long side walls, to keep the trackballs from going all over the place, but the lexan? Keeping robots on own side? Make a rule against it, or add another horizontal pipe. Entangling? Well, the robots do that now on the overpass. I'm sure there was a reason.

[Phyrxes]

I always figured it was to prevent manipulators and/or robots from "trying" to go through the center divider, that is the drive base goes under the lowest section of horizontal pipe and your manipulator gets demolished as your entire robot attempts to take a "short cut." It also presents a "solid" object on the "left" to bounce ultrasonic range finders off of.

[EricH]

Originally Posted by Roger

Now you guys have got me wondering. A quick search found me this photo which may exhibit my thinking.

The ends of the field where the drivers are have the big lexan panels. The angled corners are the chainlink fence. The center divider are 3 high lexan panels. The low outside sidewalls have lexan, but the outer outside walls are just the metal pipe - no lexan. At least I can't see any. There are no zip-ties holding the panels anyway, like the center divider wall has. I remember at the end of Final matches before the awards they were taking the pipes down on the audience side but no lexan.

Oh, the OUTSIDE ones! I was thinking of the normal field walls. You're right, those don't have any visible. I'd say that's so refs, spectators, and camera people have a clear view with no chance of reflection.

[KarenH]

Originally Posted by Roger

The ends of the field where the drivers are have the big lexan panels. The angled corners are the chainlink fence. The center divider are 3 high lexan panels. The low outside sidewalls have lexan, but the outer outside walls are just the metal pipe - no lexan. At least I can't see any. There are no zip-ties holding the panels anyway, like the center divider wall has. I remember at the end of Final matches before the awards they were taking the pipes down on the audience side but no lexan.

Originally Posted by EricH

Oh, the OUTSIDE ones! I was thinking of the normal field walls. You're right, those don't have any visible. I'd say that's so refs, spectators, and camera people have a clear view with no chance of reflection.

You're both correct. The center wall has larger diameter pipes, and the reflective panels are laced in place with substantial cable ties. The look reminds me of leathercraft projects from childhood day camps (moccasins?). The bases for the uprights are covered with carpet pieces. The thing is a bit of a nuisance to assemble, and the cable ties are a nuisance when taking it down, but it looks to me like the greatest nuisance for the field crew is keeping the carpet pieces securely taped down. One robot in San Diego ate one of the carpet pieces, along with the sticky tape, and got "indigestion."

The bases of the outer walls are placed outside the normal side rails of the field. The outer walls have no polycarbonate panels, and have smaller diameter pipes than the inner walls. They also require little or no maintenance during the competition.

From the differing construction, I conclude that the purpose of the center divider is to prevent both trackballs and robots from crossing the center of the field, so it has to be strong enough to withstand lots of rough treatment. But the purpose of the outer fences is merely to keep the trackballs from escaping. So they are neither as robust nor as impermeable as the center divider.

Furthermore, I suspect that the GDC knew very well what the effect of reflective panels would be. After all, they DIDN'T use the stuff on the corner panels.

[ReaperGoat]

Oh man...that's just...ridiculous

Couldn't they have made the top two out of the chain link fencing they used on the Robo-Coach stations? Or chicken wire, even? There are better ways to keep robots from going through without killing the visibility and putting teams at a disadvantage.