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Offside camera

using player position and ball impact sensor devices.
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Offside: attacking player (team A) is closer to the goal line than any defending player (team B) [except the goalkeeper - correction from mcscotland] at the moment when the ball is sent up the field by another team A player.

So, how about every player wears a device in the waistband of his shorts (arbitrary location really, but better than in his shoes or further up the body, waist is closer to his centre of gravity). This device is a low power transmitter on some unique frequency (you only need 20 frequencies at the absolute maximum). Using receiver/detection stations around the edge of the field, the relative distance between every player and reference points such as the goal line can be assessed and computed in real time. In the case of a possible offside call, the last recorded impact on the ball (i.e. the player's foot kicking it) is timed and measured against the simultaneous goal line distances of the defending team B players and the suspected offside team A player. If a 1% error is acceptable, the uncertainty will only be 10-20cm over a goal line-to-player distance of 10-20m.

The result, even though the computation is pretty easy and would take a second or two, would be delayed to ensure that the crowd and TV commentators have enough time to make some inane remarks and argue the case for leniency/stringency. Then on a big TV screen at the end of the park (like in Rugby League for awarding a try) A big flashing 'OFFSIDE' or 'ONSIDE' gets displayed.

For viewer interest and support for above mentioned inane discussions, this can also be combined with a dedicated offside camera, in fact that's why I thought of this - too often, TV coverage does a replay of the suspected offside moment, and the angle of the camera is completely inappropriate to be able to see. This dedicated camera would move on a low-friction runner (one of those things that forces air out of little holes), and would constantly stay at the same goal line distance as the furthest upfield player. A waveform displayed at the bottom of the screen should show ball impacts as a sort of seismic trace. The kick on the ball would be the trigger to pause the VT and assess whether team A's player really was nearer the goal line than the team B defender.
sappho, Mar 26 2002

(?) Official FIFA rules http://a1801.g.akam...tg/Laws01en1-39.pdf
A slightly more terse version of dare99's explanation. Form the FIFA rule book - see law eleven. [mcscotland, Mar 27 2002, last modified Oct 04 2004]


       Change the offside rule entirely. Get rid if it in it's current sense and have the rule that you can hit any opposing player in the area if they havn't got the ball. That'll sort out goal hangers and make the game more interesting.
dare99, Mar 26 2002

       George, Back passes to defenders are not a problem because as I mentioned in the second paragraph, each player has a unique locator frequency. This system is a tool for the ref and a gimmick for the TV companies. I never said that the machine would stop play of its own accord, just that if there was a difficult decision, that this would prove one way or another.
dare99, sure, abolish the rule if you like, I'm not in the business of deciding whether it's a good rule or not, but it does exist now and there are situations where a little bit of technology could help.
sappho, Mar 26 2002

       Correction: a player is offside if "he is nearer his opponents' goal line than both the ball and the *second* last opponent"

How does this system reconcile the "active play" clause of the offside rule?
mcscotland, Mar 26 2002

       I did mention that only 20 of the players on the pitch would need locator frequencies allocated to them, it is implicit that the goalkeeper is the last opponent but doesn't count. (Furthermore, there are also the possible cases that there is no goalkeeper on the pitch for some reason, or he may be doing a Schmeichel and be halfway up the field, and if outside the box, he *does* count as a normal player and can therefore be involved in an offside decision... However these are largely irrelevant cases!).
'active play' can be accounted for by the human management of the system. In the computation of distances, that player (who was clearly offside but was not going to receive the ball and/or was running back into an onside position) would be eliminated and the relative distance measurement would be restricted to team B defenders and the _one_ suspected offside team A player.
sappho, Mar 26 2002

       I don't want to pick poke fine holes in an idea that is still doughy so will stick to a slight kneeding.   

       You may find that radio is difficult to pinpoint exactly enough. Instead, cameras and a bit of computing power could work out where all the players are. To aid recognition, you could force all the players to wear brightly coloured hats, leading the possibility of, "Yes, Mr Beckham, we think you were on-side too but since you lost your hat back there we'll never know for certain."   

       While I'm stamping all over this, can I have a second touchline camera level with the ball, please?
st3f, Mar 26 2002

       I'm not sure how offside works in football (presuming that's the sport in question here), but this very concept translates perfectly to hockey offsides. Although, as st3f pointed out, cameras/computers would likely work better.
waugsqueke, Mar 26 2002

       //I'm not sure how offside works in football // that is so funny waugs, I don't believe ANYONE understands the offside rule. It was explained to me once by a really topnotch referee and I was not convinced that he understood it.
po, Mar 26 2002

       1st - The player must be in an "offside position" at the moment the ball is "played" by a teammate. To be in an "offside position", a player must be on the opponent's half of the field & closer to the opponent's goal line than both the ball & the second-last defender. A player is not in an offside position if he is on his own half of the field (i.e. the half his goalkeeper is on), or even with the second-to-last defender or the last 2 defenders. (The goalkeeper is usually the last defender, or one of the last two, but he might not be; the rules just refer to the last 2 defenders & don't mention the goalkeeper). This is often difficult to call. (For example, if a player is even with the Second Last Defender & thereby in an "onside position" but runs past the Second Last Defender a split second after his teammate makes a through pass. In this example, the player is not offside because he was in an onside position at the moment the ball was played.)   

       2nd - The player must be involved in "active play" by either:   

       gaining an advantage by being in an offside position, or   

       interfering with play, or   

       interfering with an opponent   

       For example, if a player is in an "offside position" but not involved in the play, he would not be "offside". This can be a tough call & can be very judgmental. For example, what if the "onball attacker" is to the right of the goal but a teammate is in an "offside position" to the left of the goal? You can argue that the teammate wasn't involved in the play, but you can also argue that he distracted the goalkeeper because the goalkeeper had to worry about the possibility of a crossing pass & therefore the attacking team "gained an advantage by being in an offside position", in which case the teammate was "offside". In this case, the Referee's decision might depend on whether he felt the Goalkeeper was influenced by the player in the offside position. Obviously, it is a very subjective decision.   

       I suggest this: don't argue with the referee over these calls. It's a very tough call and it's easy to miss these calls. (Even the best Linesmen in the world miss these calls). I suggest teaching your attackers to stay 2 steps behind the "Last Defender" and, if they don't have the ball but are running with a teammate who has the ball, to stay 3 steps behind the ball so they are less likely to be called offside. (The linesman's sight angle can sometimes make an attacker look like he's in an offside position when he's actually even with the Last Defender or with the ball).   

       Special Cases Where Offside Is Not Called: A player is not offside if he receives the ball directly from a goal kick, throw-in or corner kick, even if he is in an offside position; however, once touched, the offside rule starts and if it is then played to a player in an "offside position", offside may be called. (Note that the offside rule does apply on "free kicks"). A player is also not offside if he passes the ball backward, even if doing so leaves him in an "offside position". However, if he is in an offside position & the ball is played back to him (e.g., a wall pass), then he can be called offside.   

       There, quite simple really!
dare99, Mar 26 2002

       Yeow. What is the purpose of such a confusing rule? Is that strange set of circumstances really something to which a stop should be put?   

       Hockey offside is so much simpler, and has an apparent purpose.
waugsqueke, Mar 26 2002

       see what I mean waugs? poor deluded fool, leave him and his strange notions. how are you waugsqueke? well I trust. what have you been doing lately....
po, Mar 26 2002

       The offside rule is very useful, contrary to what you many may think. Although you may not understand the rule, don't worry, the players and referees do. Of course, it's unfortunate that it can be difficult to make the call sometimes, but it's still better than abolishing the rule: there is no better alternative. As for technology, I think that if it's possible to use it, great! Of course, there will still have to be a subjective component to the offside call due to the "active play" clause.   

       Steve, Dec 30 2002
stevenstavros, Dec 30 2002

       To throw another sport in the mix: water polo's "offside" rule is that no player can be within 2m of the goal line without the ball. The position of the defenders is irrelevant. (I don't know if this would work for football; while it would be much easier to officiate, football seems to rely on breakaways for scoring.)
bookworm, Dec 30 2002


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