A controversial question about line calls

Discussion in 'Adult League & Tournament Talk' started by sureshs, Sep 23, 2013.

  1. RetroSpin

    RetroSpin Hall of Fame

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    Totally agree. If it's so close you have to have an internal debate, the odds are very good it got the line.
     
  2. dcdoorknob

    dcdoorknob Hall of Fame

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    For whatever it's worth, this graphic is inconsistent with shot-spot every time I've seen it on TV. Shot-spot does show elongated marks where the ball landed, but those marks are not 3 ball lengths long. Maaaybe 2, usually more like 1.5 'uncompressed' ball lengths, but definitely not 3 imo. Of course it will also depend on how trajectory and pace of the ball.

    Is it your opinion that the makers of shot-spot have this wrong too?
     
  3. schmke

    schmke Professional

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    I come to net a lot, and as a result am in the position of having to call balls in/out on the baseline behind me or on a sideline where I'm perpendicular to the line, or again it may be partially behind me. These calls are difficult to make and there are many that are close and may be out, but I didn't see them out so I call them in or ask my opponents view. Once I ask though, it is in unless they are willing to say they saw it out.
     
  4. Ronaldo

    Ronaldo G.O.A.T.

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    Again, guys do not know where the ball landed on clay with a clear mark. On a hard court, good luck.
     
  5. user92626

    user92626 Legend

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    In recreational level, the fact that the ball itself is in or out is irrelevant! The keys to handle line call is a combination of honor and insistence.
     
  6. Ronaldo

    Ronaldo G.O.A.T.

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    Insistence???
     
  7. tennis_ocd

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    I think this picture and shot-spot are computerized images; neither are actually representative of what has physically occurred. Computer can take into account ball trajectory; probably not spin (or not even surface?) to make a "fake" footprint. Clay footprints can be quite long for hard flat backspin shots. I'd imagine grass even more so.

    Bottom line, we all must make a call and in my experience of rec playing and watching, 10x more out balls are played than good balls being called out. Would guess this goes down significantly as level, intensity and awards get ramped up. Fact is one is at a serious handicap if continually playing out balls to ensure this mythical 100% accuracy standard.
     
  8. goober

    goober Legend

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    I think he means you must insist that you called it right no waffling. I think in rec matches if someone is firm about a call that things will go smoother whether you are actually right or not about the call. As long as you truly believe what you saw, then it is ok. The problem is when you get people who keep on "insisting" bad calls:)
     
  9. tennis tom

    tennis tom Hall of Fame

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    I wish a "call" was made, a lot of rec players don't make "calls" or must imagine they do. Ball lands near opponent's baseline and they leave you wondering "How was it ??". No finger or palm to indicate in/out, no audible call--you finally ask them because you want to know what the score should be inquiring, asking and then needing to shout increasingly louder--then they finally reply, "Can't you hear? I shouted it out." Oh NO they didn't! After a while you tire of continually asking for calls and give up on the match using it for practice, no longer caring about the score either, vowing not to play with these dregs again.

    I'd like to know where this tennis heaven is where 90% of out balls are played? That's not my experience, I'd say more the opposite--maybe it's regional and got something to do with water fluoridation.
     
  10. Ronaldo

    Ronaldo G.O.A.T.

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    Suspected that is what he meant. See guys who refuse to play on the same court as players who consistently make bad calls in their favor.
     
  11. TimeSpiral

    TimeSpiral Professional

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    I'm assuming by shot-spot you mean HawkEye?

    The source material for that graphic I made is a high speed video shot and demonstrated by HawkEye.

    In one statement, relating to the source video (emphasis added):
    Regarding accuracy specifically, it's interesting to observe high speed video footage (1000fps), similar to that obtained during ITF testing. You can clearly see the ball squash, skid and roll off the surface, spanning some 10cm before becoming air borne once again. If viewed from a regular broadcast camera (25fps), its clear that the viewer's perception of where this ball had landed will be influenced significantly by the limited frame rate and zoomed out field of view provided by live broadcast footage. In this example, it would be easy to argue from one end of the sequence to the other that the ball landed within 2mm of the back edge of the line, or at the other end of the sequence almost 10cm outside.​
    I don't know how they're getting that number. You can clearly measure the distance in the video with some basic video forensics (which I did), but: Let's call a tennis ball 6.3 centimeters, uncompressed. It's reasonable to expect that in some instances, a ball that looks nearly two ball lengths out, was actually in.

    By this picture are you referring to the graphic I posted? The source material for that graphic is a high speed camera capturing a real event. And yes, obviously the HawkEye broadcast images are computer generated, but that data is gleaned with the HawkEye system, which captures the raw data from the court.

    This statement that you made is just incorrect. It's doing precisely the opposite, in a manner many times more accurate than a human being can be. Another less pertinent example: This line of text your reading is being generated by your computer. It represents the physical occurrence of me typing this information. I assure you, this actually just happened. :twisted:
     
  12. user92626

    user92626 Legend

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    goober got it correct. I observe again and again that calls often go to the one who's firm and assertive. Even when the call doesn't belong to him in the first place but if he insists strongly, he would likely get a re-play. Coincidentally, last night I instinctively developed this strategy after my opponent made a couple questionable calls: I didn't simply just gesture that my team's passing shot was in, I outwardly "celebrated" immediately with "Oh YES! Awesome" :) Saying it immediately and firmly erased any doubt that our opponents might have had. Haha.

    If you get that kind of players, there's not really that much you can do other than either 1) keep your honor (don't sink to their level) and play even a better game, or 2) insist back that you are right when it's your turn. See, it always comes down to who argues better, holds his belief stronger.
     
  13. dman72

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    A guy I played the other night was killing me with this.

    I called his first close ball in....even though it was probably an inch or 2 out, it was a good shot and I gave it to him.

    He proceeds to make at least 4 bad calls on shots way too close to call out...one that was clearly on top of the line, not even on the outside of the line. And that one, when I gave him the "you sure?" look, he says "I saw that one clearly."

    This was inside out forehand from the T on my side that hit right on top of the line near his service line ad court..he was 4 feet behind his baseline shaded towards the deuce court. I was as close to the ball as him after following through, and had a better angle.

    I try to tell myself to make sure everything I hit is inside the line..but then there's one guy in my league who calls balls inside the line out. It gets tiring after awhile.
     
  14. goober

    goober Legend

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    Personally I hate teams that do this. This strategy I have noticed has been going around some of the leagues I play in. Doubles team will outwardly very visibly celebrate any close call before any call is made in attempt the steer the opponents into make the call in their favor. Then they act upset or in disbelief if you call it out. Clearly low brow gamesmanship IMO .
     
  15. tennis tom

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    This is where you throw the "benefit of the doubt" thing out the window, against a TRUE CHEATER. It's no longer tennis so forget about the code. Start closing your eyes a bit on the close ones and give the "benefit" to yourself. I've found when "playing" a true cheater, cheating them back works. They will now respect you, or fear that that you are even a better cheater then they are and their game crumbles and they tank early retreating to the bar. Give them an egregiously bad call where you both know it was a really bad call. Look them in the eye as you do it and smile, stand your ground--you don't go to hell for a bad call on a tennis court.
     
  16. user92626

    user92626 Legend

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    dman,

    IMO, it's quite rare or blatant cheating or involving very bad eye sight to run into FOUR calls of this kind, especially at 3.5 (going by your signature). The shots in this level tend to be slow which makes it difficult to lie! Not to mention if 3.5 skill is enough to go for the line that much!!

    But let's assume both of you hit the line a lot -- but only 4 of which got questioned, you can always retaliate by making similar calls. When he does 2, you do 1 (karma is still on your side). That kinds of even it out. And, what is the chance that a match is determined by a couple of points?

    The way I see it. there's a lot of room for a better, level headed player to prevail.
     
  17. user92626

    user92626 Legend

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    I don't blame you if you are an honor player/team. You have to remember that I do this in the context of dealing with a bad team. Like I said, it's involved honor. IMO, I don't have to be completely honorable in the face of very shadiness. I just need to be a little more honorable and honest than them to live with myself. It's a competition. :)
     
  18. Jay_The_Nomad

    Jay_The_Nomad Professional

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    Sportsmanship works the other way around too.

    When your opponen calls it out you need to accept it sometimes.

    Played a real hot head earlier this year. He has a real fast serve but nothing else so he tries to go for as many free points as possible. The thing is people often give fast servers the benefit of the doubt because the sheer speed can sometimes make you doubt if it's in and out.

    Anyway long story short, I called a fault on his first serve ace on my partner who was returning. The ball was long. Needless to say, out of the four of us I was in the best position to see the ball. So I called it out, and the guy flares up and throws this major tantrum. My partner who is spineless decides to concede and give them a let. He serves again and it is clean ace again, but once again just long. I call it out again, the guy blows up big time and starts ranting. His partner tells him to calm down. My partner loses his nerve again and concedes the point.
     
    Last edited: Sep 25, 2013
  19. Silent

    Silent Semi-Pro

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    Yep, goes both ways.

    As Carey Price would say, some need to just "chill out".
     
  20. Ronaldo

    Ronaldo G.O.A.T.

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    If he throws a tantrum, call his good serve out too.
     
  21. dman72

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    I am a feast or famine inconsistent 3.5. I hit a lot of shots all over the place...some 2 feet out, landing short of the service line, and everything in between..but I do hit some big forehands that clip the baseline quite often during the match. Depending on how cheesy the guy is across the net, these are winners or errors. Same thing with first serves.

    Everyone try this: take a ball and put it 3 inches behind the service line directly in front of you. Now stand in your normal receiving position straight back. If you call that ball out, you are purely guessing. You do not see space between the ball and the line..it's not physically possible. When you call that out, more likely than not, you've called balls on the line out because you take the same guess and expand it. I'm pretty much known for giving guys serves as much as 6 inches out that hit in front of me, because I can't HONESTLY say I saw it land out...I'd be guessing otherwise. ..a few guys get mad at me for this because they stop playing but I'm returning the ball for the reason I stated above. I tell them keep playing until you hear a call. If I don't see green/blue whatever between the ball and the line..it's in. That or stop serving right at me, because sidelines of the service box I call as I see.
     
  22. tennis_ocd

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    No. Hawkeye captures ball flight characteristics and interpolates (guesses at) the court strike point. It has an inaccuracy of over 1/8"! -- much more inaccurate than the human eye (where we have guys here touting their fuzz was on line.)

    But it does provide cool tv graphics.
     
  23. tennixpl

    tennixpl Rookie

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    I feel ya. and hitting farther in at some point just does no good bc you then can't hit a winner or force action. of course its one more aspect of the game we have to learn to deal with.
     
  24. JackB1

    JackB1 G.O.A.T.

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    I don't really understand this thread? You don't make line calls based on probability. You make them on certainty. If there is .000000001% chance the ball might have caught a sliver of the line, the size of a flea's short hairs, you call it "in". End of story.
     
  25. TimeSpiral

    TimeSpiral Professional

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    No, dude. Haha. Interpolate does not mean guess. Guess means guess. Interpolation is a mathematical technique used to fill in gaps. In this case; gaps caused by sampling rates (frames of visual data captured per second, aka. FPS).

    For instance, if I'm sampling a visual information of the ball at 60 FPS, I can accurately create a trajectory, calculate velocity, and when I combine this with synchronized data from multiple angles, I can triangulate exact locations and recreate an accurate simulation. When the math is determined by analyzing the raw data, the system can interpolate the data points in between the frame rate (which may or may not be 60 frames per second).

    HawkEye:
    Although a protocol remains if the officiating system is not able to provide an answer with utmost confidence, this is an extremely rare situation, where onsite operators are not 100% confident in the accuracy of the system for that given shot.

    Go to that link, scroll down, and read, "How does this work." It's not guessing.
     
  26. Max G.

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    There's no such thing as certainty when you're dealing with fallible human eyes. If you are ever certain about a line call, the certainty is a figment of your imagination. If I called balls 'in' when there was only a 0.000000001% chance of them being in I would have not made a single out call in the past 15 years.
     
  27. Max G.

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    For reference - if you claim there's less than an 0.000000001% chance of a mistaken call, that means you could make one call per second for the next three thousand years and not make a single mistake.

    I'm pretty sure there is not a single thing a human being can do, ever, with only an 0.000000001% chance of failure.
     
  28. tennixpl

    tennixpl Rookie

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    and reading the link it states

    "Results showed the system to have a mean error of only 3.6mm when compared to a high speed camera located on the playing surface"

    3.6 mm = .1496062992in > .125in = 1/8 in
    don't know where 1/8th comes in but more than 50% of the time Hawk Eye is worse than that, i really doubt a lines man can call a ball to within an 1/8 of an inch even right in front of them.


    and yes interpolation is a guess, its just a mathematical guess instead of a random one.

    and for all those ppl who say line calls aren't about probability well this whole Hawk eye thing is nothing but probability, as well as the error associated with humans calling lines.
     
  29. struggle

    struggle Hall of Fame

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    I think i wouldn't enjoy playing you, and definitely not WITH you..

    If it's out, fine. If you're not sure, it's in.

    Now go kick some rocks.
     
  30. JackB1

    JackB1 G.O.A.T.

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    You are telling me if I see that a ball is several inches inside the line and I call it "in", I am not "certain" it's in? I don't really follow what you are saying? When a ball is 10 feet out, you are not "certain" it is out?
     
  31. JackB1

    JackB1 G.O.A.T.

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    ^^^^^^

    that is all you need to know :)

    I still don't understand the op's point?
     
  32. JackB1

    JackB1 G.O.A.T.

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    Your analogy between a tennis line call and a surgeon on removing a tumor, couldn't be more inappropriate.
     
  33. user92626

    user92626 Legend

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    In mathematics what you said is near certainty, for example 99.99999999999999% certainty. The uncertainty percentage is so small and cannot be processed by humans that we just round it up and consider it 100%. Did you know that in physics there's a chance that you could walk through a wall?

    However, the certainty gets less when the ball gets closer to the line and that's the topic here. Not the shot that's 10 feet away. When it gets too close our call is mainly done through a combination of (fallible) vision, guessing, experience and nonetheless some competitive shadiness. At this point it likely becomes a matter of the player's verbal skills, ie his argument and insistence or someone's taking the honorable, high road rout, ie yielding. That's how the matter is resolved/handled, per the OP's asking.
     
  34. Max G.

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    99% certain, not 99.99999999%.
     
  35. TimeSpiral

    TimeSpiral Professional

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    Dude ... You're just making stuff up.
     
  36. sureshs

    sureshs Bionic Poster

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    Be afraid of the purists here.

    They will immediately object to your use of "probably." How dare you say that there is an element of conjecture there? And 1 inch vs 2 inch? Either it is 1 or 2. You are not allowed to make such statements here.

    Besides, I think the problem lies in the second sentence. It is not a good shot if it was out. So why do you have to give it to him?
     
  37. sureshs

    sureshs Bionic Poster

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    If you can be certain, either of the outcome or the probability, then there would be no need of Haweye.
     
  38. sundaypunch

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    Logic like that will never get you to 27,000 posts.
     
  39. sureshs

    sureshs Bionic Poster

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    Some teachers round up 88% to A, others don't.

    Look at it this way. By using confidence levels, you are preparing your opponent for real life situations in other matches. He will learn that he cannot keep hitting close to the lines and expect his opponent to always call it in because there is a 0.000000001% chance.
     
  40. tennis tom

    tennis tom Hall of Fame

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    In my day that would have been a B+, hopefully those teachers are not teaching math.
     
  41. kingcheetah

    kingcheetah Professional

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    I don't really understand this thread... If you aren't certain about a ball being out, it is in. If you and your opponent are hitting the line every time, or hitting it so that each thinks that it *may* be out, but cannot say so with certainty, you have to call it in. Saying that the opponent will learn not to hit close to the line if you call balls out that you aren't completely sure on is unethical.

    Side note: You can't draw analogies between crimes that may have been committed and whether or not a tennis shot was in.
     
  42. Bdarb

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    Thank you! Someone finally said it haha.
     
  43. Jay_The_Nomad

    Jay_The_Nomad Professional

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    I think the most fair way to play is to ask yourself if there is a slight chance the ball might have clipped the line. If yes than the ball is good simple a that. I think we should do this particularly when the opponent is legitimately constructing points.

    If you saw what looks like an out ball. Just call it out. There is no guarantee you are going to be correct. But if you think it is out and really unlikely that it caught the line then call it out. Dont second guess yourself or try to be generous. Just be fair about it. And that includes being fair to yourself.

    If the guy is a pain in the rear - e.g. He throws tantrums, cheating etc. - then go ahead and be more stingy on those line calls.

    You will learn to self modulate after a while.
     
    Last edited: Sep 26, 2013
  44. dcdoorknob

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    I figured I'd expand on this a bit. Just coming from a probability/stats perspective.

    When someone says they always only call balls out when they are 100% sure the ball was out, that can (in theory) be verified, by going back to each out call they've ever made and finding out if it was indeed out. Also, if this claim is true, then they can rightly expect for every single out call they make in the future to always be accurate

    If this person has ever called an in ball out, then by definition their claim that they only call balls out when they are 100% sure it is out is incorrect, since if that claim was true then there would be no incorrect out calls ever.

    The problem is with the person's estimation of their own 'sureness' level. They may think they are 100% sure, but if in reality only 99% of the balls they call out are indeed out, then what they are really doing is calling balls out when they are, on average, 99% sure the ball was out.

    Someone else, who calls lines exactly the same way as above, but instead realizes that they have probably called an in ball out before, and probably will do so again in the future at some point, and may shy away from saying that they only call balls out when they are 100% sure, because they realize such a statement would just not be true in reality. But it's not because they are less honest than the first guy with the 100% claim. It is actually because they are trying to be more honest with their own percentage claims for themselves than the first guy.
     
  45. tennis_ocd

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    It is still a mathematical "guess" (although in this case _extrapolates_ would be a more accurate choice of words -- even more of a mathematical guess.) The machine mathematically guesses to within perhaps +/- 1/8 of an inch and throws up a cartoon like graphic that many appear to take as absolute truth.

    Actually kind of amusing to see on every _very close_ ball and tv zoom of strike the software default to show the ball EXACTLY the same distance from line -- either a mm wide or mm on; never so close and uncertain that a human mind would have to engage.
     
  46. stapletonj

    stapletonj Semi-Pro

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    "you don't go to hell for a bad call on a tennis court."

    ____

    Oh yes you do! Purgatory is a possibility, where you play on concrete courts with bad knees and dead balls. You play the Devil, who of course is a pusher. He also cheats like CRAZY on line calls. But, b/c you are trying to avoid going down instead of up, you have to be super honest on your calls, because there is a set of angelic line judges who will not interfere, but WILL keep track.....

    Hell......no tennis at all.....

    Heaven............grass courts of course.........
     
  47. TimeSpiral

    TimeSpiral Professional

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    [​IMG]

    I do appreciate you clarifying your--err--"understanding" of this issue. I'm going bow out here; not going to argue with a dude who equivocates high-level math with "just guessing."

    And, no: it's not extrapolating. It's interpolating a predictable behavior.

    And just for visual purposes:
    [​IMG]
     
  48. sureshs

    sureshs Bionic Poster

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    If it is "really unlikely" that the ball was in, you should call it in, as per the moral people here. You can call it out only if you don't use terms like "really unlikely" and declare yourself to be certain.

    I like the idea of being fair - to the situation and to yourself. And self-modulation.

    You have beautifully captured the essence of what I am saying.
     
  49. sureshs

    sureshs Bionic Poster

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    Correct. Interpolation is still a guess, as it creates data where none exists. The simplest technique is linear interpolation, and then there is more sophisticated curve fitting. I think rarely is anything beyond cubic used.

    The graphic on TV is misleading as you point out. It is the zoomed version of the mathematical projection - not of what really happened. Like zooming into the mouth of T Rex in Jurassic Park does not mean there was a real T Rex there.
     
  50. TimeSpiral

    TimeSpiral Professional

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    Those graphics you're seeing on TV are "vector" graphics, which can theoretically be scaled infinitely without loosing accuracy or clarity.
     

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