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The Technology Behind the Magic Yellow Line

Posted by ryuzaki0 on from the don't-eat-the-yellow-line dept.

CurtMonash writes "Fandome offers a fascinating video explaining how the first-down line on football broadcasts actually works. Evidently, theres a lot of processing both to calculate the exact location being photographed on the field — including optical sensors and two steps of encoding — and to draw a line in exactly the right place onscreen. For those who don't want to watch the whole video, highlights are here."

32 of 261 comments (clear)

  1. New trend by plankrwf · · Score: 5, Interesting

    Hmmm... A new trend? No longer reading 'have not RTFA' but 'have not Viewed TFA'?
    Dear oh dear, what is /. coming to.

    1. Re:New trend by BlackCobra43 · · Score: 4, Funny

      I didn't RTFC but I'm going to assume you posted something funny and voice my approval.

      --
      I never spellcheck and I freely admit it. Save your karma for more worthwhile "lol erorrs" replies
  2. Watch the video by Baricom · · Score: 5, Interesting

    I already knew in pretty significant detail how all this works, but there was a lot of additional information in the video that never made it to the PR-sanitized behind-the-scenes descriptions of the technology.

    Plus, you get to see the ugly UI that appears to have been built as an afterthought - just like the UI of all the other industrial television software I've operated.

    1. Re:Watch the video by direktorxxx · · Score: 5, Insightful

      Plus, you get to see the ugly UI that appears to have been built as an afterthought - just like the UI of all the other industrial television software I've operated.

      It's true, 90% of software that I've used in a television studio has a poorly designed, or worse, broken, user interface. Gets the job done but in the most convoluted way. The only well made interfaces are the ones by major companies who have been around for a while, ie Newtek, Adobe, Pinnacle, Chyron.

    2. Re:Watch the video by Spy+Hunter · · Score: 5, Insightful

      Well, when you have a user base in the dozens, and operating the UI is the user's entire job, it doesn't have to be intuitive or even easy. It's cheaper to teach a few dozen guys how to use a bad UI than it is to design and program a really good UI.

      Honestly, the UI in the video didn't seem too bad though (from a 10-second impression). Sure it was ugly but it seemed to have useful features for the operator; did you notice when the guy dragged the line of scrimmage past the first down marker it automatically reset the first down marker to +10 yards?

      --
      main(c,r){for(r=32;r;) printf(++c>31?c=!r--,"\n":c<r?" ":~c&r?" `":" #");}
    3. Re:Watch the video by RegularFry · · Score: 3, Insightful

      Unfortunately you'll have the word "unfamiliarity" thrown right back at you. It's a bigger hurdle than you might think.

      --
      Reality is the ultimate Rorschach.
    4. Re:Watch the video by Reality+Master+101 · · Score: 4, Informative

      The way we used to say this in the Hospital game is, "different-good is as bad as different-bad."

      --
      Sometimes it's best to just let stupid people be stupid.
  3. My Idea For a Football Field by cleatsupkeep · · Score: 4, Interesting

    Would be a field that uses clear/transparent turf. and all colors on the field are defined by lights under it. The white in the 10/20/30... could be done dynamically, the end zones could be designed dynamically and relit, heck, you could switch from a green field to Boise State's blue.

    This could be used to make the same field a football field, soccer field, lacrosse, field hockey... all without the the clutter of all the lines on one field.

    This might be tricky with turf technology currently, but I feel like a first technology to do this might be a basketball court (lights for basketball, volleyball, etc)...

    It probably isn't feasible, but would be interesting.

    1. Re:My Idea For a Football Field by wicka · · Score: 4, Interesting

      ...grass.

    2. Re:My Idea For a Football Field by RockMFR · · Score: 4, Funny

      Was this idea invented by Shampoo?

    3. Re:My Idea For a Football Field by Ihmhi · · Score: 5, Funny

      You're thinking a bit too far ahead, I think. I say we just hack some Roombas with spraypaint cans and GPS and let them sort it all out.

      --
      Random Thoughts From A Diseased Mind (Not For Dummies)
    4. Re:My Idea For a Football Field by Kickasso · · Score: 5, Funny

      Lessee. The football field is 360 by 160 feet. You need a resolution of at least 1 inch This is very coarse, really, but let's say it's 1 inch. This means your field is a giant 4320 by 1920 color screen right here. Which is, like, quad HDTV or something like that. You know what? Fuck the game, let's see some movies.

    5. Re:My Idea For a Football Field by citizenr · · Score: 4, Funny

      genetically engineered light emitting grass?

      --
      Who logs in to gdm? Not I, said the duck.
    6. Re:My Idea For a Football Field by Authoritative+Douche · · Score: 3, Funny

      OLEG

  4. Weathermen have been doing this for ??? by MerlynEmrys67 · · Score: 4, Insightful

    Yeah - it is one guy and as long as he doesn't put on an annoyingly green tie - it all just works. It is actually amazing how much technology is behind simple video effects done seamlessly. I thought it was funny when Forest Gump won the oscar for special effects - everyone was like... that isn't a special effects movie... I was like - that is the point

    --
    I have mod points and I am not afraid to use them
    1. Re:Weathermen have been doing this for ??? by iluvcapra · · Score: 4, Informative

      Yeah - it is one guy and as long as he doesn't put on an annoyingly green tie - it all just works.

      There are several substantive differences:

      • The green or blue weather map is a straight chromakey, the matted background is opaque and the removed background is monochromatic. The first-down line/overlays have to be added to a surface of varying (but reasonably predictable) colors, and it's laid over the action, with objects "in front" (not grass) matted out of the overlay. This is very complicated.
      • The camera is in motion, panning and tilting while the overlay is happening. The weatherman always does his schtick in front of a camera on "lockdown," because if the camera moved, the weatherman would move (w/r/t the frame) on a different plane from his chromakeyed background.

      I'd read the article if it weren't slashdotted, it appears very interesting...

      --
      Don't blame me, I voted for Baltar.
    2. Re:Weathermen have been doing this for ??? by Rich0 · · Score: 4, Insightful

      Don't forget the live component. There is a big difference between a movie where you have 6-18 months to add in FX, and a TV broadcast which is at best delayed a few seconds. In a movie you can conceivably tweak your algorithms to catch the unexpected or clean up a few frames by hand if needed. With live the whole thing needs to work in realtime automatically.

    3. Re:Weathermen have been doing this for ??? by peacefinder · · Score: 4, Insightful

      Yeah, I remember very clearly when I first saw the "magic yellow line" some years ago. I watched for a couple minutes before I realized what the line meant. I turned to my friend and asked "You know what that yellow line means?"

      He said "Yeah, that's where they have to go for a first down."

      I said, "That too. But what the line really means is that you can't believe live video any more."

      --
      With reasonable men I will reason; with humane men I will plead; but to tyrants I will give no quarter. -- William Lloyd
    4. Re:Weathermen have been doing this for ??? by sjames · · Score: 4, Interesting

      What really brought it home (so to speak) for me was baseball. If you look carefully, occasionally you can notice that the advertising behind the batter doesn't quite move with the rest of the frame when the camera shakes. While the yellow line couldn't be taken as really existing, you could believe the advertising was actually on the wall.

      While that's harmless enough, it shows that convincing covert alterations in real time are also possible.

  5. The only yellow lines in Australia... by Laser_iCE · · Score: 4, Funny

    are the ones on the platforms at train stations. (In QLD anyway) The closest thing we have to this in sports around here is either during swimming, or between balls during a test match, when the commentators are bored and start drawing lines all over my TV.

  6. Flamebait +1 by Anonymous Coward · · Score: 5, Funny

    I thought Football was a game played with your feet! What the article discusses is a bastardised form of Rugby.

    1. Re:Flamebait +1 by cdrudge · · Score: 3, Insightful

      Football doesn't require you to know where the magic yellow line is at to understand what's happening. The refs seem to be able to do it as well as the 22 players on the field or more on the sidelines. It's there on screen is the first down markers aren't always visible. If the shot is zoomed in on the play, a ref's standing in front of the marker, etc you can't visually see where the first down point is at.

    2. Re:Flamebait +1 by Neoprofin · · Score: 4, Insightful

      May I remind you that the U.S. is the only country to win to win 2 Olympic golds in Rubgy, and it happens to also be the only two years they competed, primarily with a team of (american) football players and track athletes?

      If the IOC hadn't dropped Rugby from the summer games it'd be interesting to see how developed Rugby in America would be. The reason for the padding, like it or not, is that American football developed into a game with much larger, stronger, faster, players rather than a slogged out game of endurance. It's not a question of superiority or toughness, there are few American football players who I think would be able to play an entire Rugby match in the style they play now, on the other hand I don't see a lot of Rugby players who I think would particularly effective on the NFL field trying to push around guys who would regularly 100lbs heavier and who are built and trained to be very good at pushing for 40 seconds at a time then taking a break.

  7. Re:unreality TV -- digitally inserted ads by Ihmhi · · Score: 5, Interesting

    That's true, but I was always more fascinated by the stuff they did for NASCAR. Not only do they use on-screen tech, but they also make use of GPS to do those fancy graphics showing info on the cars while they're moving on the road.

    There was an article about this particular tech NASCAR uses in some magazine, but I can not for the life of me remember it, nor can I find any videos demonstrating it...

    --
    Random Thoughts From A Diseased Mind (Not For Dummies)
  8. Youtube Mirror for the video by iammani · · Score: 4, Informative

    http://www.youtube.com/watch?v=Vh9af_gXxlM&fmt=18

  9. Re:nerdiness by Yvanhoe · · Score: 4, Insightful

    Can't we just call it genuine curiosity ?

    --
    The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
  10. Re:Amazing... by ITFromHome · · Score: 3, Informative

    "completely arbitrary position"
    The referees of the NFL (which I am not) would tend to disagree. I'm not trying to start a sports discussion off-topic but remember that the yellow line is only for home viewers. The measurments of the first down are very exact once the referee makes the initial spot of the ball. The NFL will NEVER take away that power from on-field persons...but back to the yellow line. TV viewers have a perspective which selects only the players at the start of the play that eventually narrows in on only the ball carrier. Before the yellow line TV viewers could not see the sidelines during a play, which is where the "chain gang" remain. Everyone in the stadium can reference the sidelines. Now TV viewers can reference the yellow line.

  11. Re:The reason for SI units by hal2814 · · Score: 5, Insightful

    "First of all, when someone writes "football" on slashdot. Is he referring to what is commonly known as "football" all over the world, i.e. "soccer" or what is commonly referred to all over the world as "american football"?"

    Sometimes a single word has more than one meaning, especially among different cultures. When that is the case, you have to use something called context to derive which meaning the word has. So "football" could mean a few different things when written on Slashdot depending on who wrote it. Lucky for us, we're given a LOT of context here. Given that we're talking about first down lines and there's ample video showing the sport in question, the context should be pretty obvious. But since you're confused, what they're referring to would likely translate to "American football" in your vernacular.

  12. Re:unreality TV -- digitally inserted ads by jhsewell · · Score: 3, Interesting

    And it was awesome that Pixar reproduced these glitches in the opening scenes Cars.

  13. Re:The reason for SI units by xaxa · · Score: 5, Insightful

    The traditional system of measurement that exists here rarely causes significant difficulties in every day life.

    200g of steak mince per person. 17 people. I'll have 3400g please.
    6oz of steak mince per person. 17 people. 102oz... but I can't ask for that. How many pounds?

    Large bottle of vodka: 1 litre. 1000mL. Double measure: 50mL. Bottle has 20 double measures.
    Normal bottle: 0.75L. 15 double measures.
    I think you buy vodka in a "fifth", a fifth of a gallon, and I think a double measure would be 2 fluid ounces. Erm...

    My wall: 4.37m by 2.39m. Area: 4.37m*2.39m = 10.4m^2. The can of paint covers 10m^2, damn.
    Your wall: 14 feet 4 inches by 7 feet 10 inches. Area... 172in * 94in = 16168 square inches ~= 112 square feet. The paint covers 10 square yards, is there enough? (No)

    I don't really see how the benefits would outweigh the costs of forcing people to switch over. Many things are already labeled with both sets of units anyways.

    Due to pressure from the EU ;-).

    I have a set of SI wrenches and a set of "standard" wrenches.

    That's twice as many wrenches as you'd need if everything came with one system of fixings.

  14. xkcd saves the day! by ConanG · · Score: 3, Funny

    And really, if you've lived with non-metric units all your life, it is easy. I have no problem knowing what size and 8 oz tenderloin or 16oz strip steak is or how big it is. I'd be completely lost trying to, off the top of my head...buy or cook with metric units. When I college in a lab, sure, no problem in doing chemistry experiments in metric, but, that isn't real every day life stuff.

    I know how to dress when it is 72F outside. I'd have no clue what to dress for at something like 32C (random temp)...

    A handy guide to converting to metric.

  15. It's not just the yellow line by Animats · · Score: 4, Informative

    Not being a sports fan, I don't see much of this stuff, but I once visited the company in Silicon Valley that makes the gear. The "yellow line" is one of the easier applications. It's basically a camera with encoders driving a fairly simple video processor. Calibration is manual; there's a setup display that shows the normal lines of a football field, and someone aligns the corners to match the real image from the camera. When the generated image matches the real one, the system is in alignment.

    That's 1998 technology. The newer systems have gone way beyond that. Ads on billboards are sometimes replaced using the same system. Ads you see on the air may not be what people in the stadium are seeing. There's player tracking, ball tracking, the "virtual strike zone" for baseball, GPS-based tracking for NASCAR, and virtual billboard insertion into everything.