Yellow first down line doesn't show up to game.

January 1, 2007 9:34 PM

Yellow first down line, but not in bad weather?

I was watching a football game (I think it was the Broncos) and the announcer made a comment about not being able to generate the yellow line showing the first down because of weather. How would weather effect the computer generated imaginary line? Is it as simple as the equipment not making it to the stadium?

posted by unreasonable to Sports, Hobbies, & Recreation (14 answers total)

The cool way they do it now requires a computer to evaluate the camera shot to identify position and perspective, so that it can correctly draw in the line as needed.

I bet rain introduces enough noise into the image so that the computer no longer is capable of figuring the image out.
posted by Steven C. Den Beste at 9:36 PM on January 1, 2007

(If they were smart, they'd put rotary encoders on the camera mount so that the computer could directly read the camera position...)
posted by Steven C. Den Beste at 9:37 PM on January 1, 2007

Best answer: I don't think this was directly weather related. They made the comment later that they couldn't get the equipment for generating the yellow line into Denver in time for the game because the airport had been closed.

This implies that the equipment moves with the camera equipment and is not provided by the stadium.

The networks probably have 1 set of equipment for each game and fly them around from stadium to stadium.

Anyway, that's what I got from the discussion.
posted by rsclark at 9:43 PM on January 1, 2007

Snow on the field is a problem because the system can't tell the snowy field from the white on the player's jerseys, and it's only supposed to show the line on the field.
posted by smackfu at 9:44 PM on January 1, 2007

Wikipedia says:

The only pixels that should change are the ones that are the same color as the field, typically several shades of green. As a result, there are two situations that are difficult. One is when the player's uniform color nearly matches that of the field (for example, the Green Bay Packers' jersey on a bright, sunny day). The other is when the field itself changes, like during a rain/snow storm or if the grass field becomes very muddy. In those cases, the field's color palette would need to include brown and/or white shades.
posted by danb at 9:47 PM on January 1, 2007

They clearly explained at 2 points in the broadcast that the snow-blocked roads (i.e., "weather") had prevented their equipment truck from arriving in Denver. That's why the yellow line wasn't working during that game.

The yellow line even worked during the Monday Night snow game in Seattle earlier this year, though it wasn't perfect.
posted by ikkyu2 at 10:33 PM on January 1, 2007

I would tend to agree with rsclark. Generating a yellow line requires modifying each video frame in real time - 24 frames per second, and each modification is a complicated problem (ie differentiating grass from players). That requires serious - expensive - computational horsepower. I read somewhere that the company that does it just has all of the equipment in one van which they park at the stadium where it can hook up to the live video feeds. The cost of the equipment is high enough that there are a small number of these vans.
posted by PercussivePaul at 10:34 PM on January 1, 2007

Based on what I've always heard from game broadcasts, including when the "1st & Ten line" first came out, smackfu and danb have it. rsclark might be correct in this one instance, but otherwise, it's a color thing.
posted by SuperNova at 10:35 PM on January 1, 2007

rsclark has it almost right. The highway into Denver was closed for days, and the Fox truck that was carrying the special computers that make the line was stuck on that highway, some 300 miles away, according to the announcers' comments. They said that they borrowed their video equipment from TBS. The game was in HD and they had the usual on-screen graphics, but some of the annoying sound effects and transition graphics were MIA.

Probably whatever program they use to generate that yellow line isn't something they could just download over the internet onto TBS's production computers. And to rip the computer out of the truck and fly it into Denver was probably seen as too risky and costly to be worth it. (I remember hearing that the lines could cost as much as $1 million per game to generate, though that was a few years ago when they first came out.)
posted by raconteur at 10:37 PM on January 1, 2007

The yellow line you are talking about is generated by a system made by Sport Vision. You can learn more about how it works here. The system needs to know the color of grass so that it can only draw on the ground and not over players, but it is adjustable so it should be able to deal with an alternate color field (white, brown, etc.)

It probably was getting the equipment to the stadium. From the HowItWorks article it says they need 4 people, a tractor-trailer rig full of gear, 8 computers, and special camera tracking hardware that has to be attached to a number of the existing cameras.
posted by cmicali at 4:34 AM on January 2, 2007

so is all that expense and effort cheaper and easier than having the guys stand on the side of the field with the sticks?
posted by medium format at 4:46 AM on January 2, 2007

No. It's more expensive and more difficult, but it's easier for the TV audience, which is the only audience that really matters. The people in the stands at the game are extras in a TV show.
posted by kirkaracha at 5:01 AM on January 2, 2007

medium format: the guys with the sticks still mark the official lines, as the announcer will remind you that the yellow line is not official and may not be 100 percent accurate on close calls.
posted by yeahyeahyeahwhoo at 8:38 AM on January 2, 2007

The guys on the side of the field are still there since they are their measurements are the system of record that is used for the game. The Yellow line (and the blue one and the red one and all that other jazz) are just for making viewing of the game easier for the tv audience. Although I must admit, the yellow line is usually pretty accurate.
posted by mmascolino at 8:40 AM on January 2, 2007