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Michael Tucker

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36 minutes ago, Sciatika said:

Silly question...

A quick human can run at about 30km/h and possibly faster in short bursts. That is about 8m/s. At standard frame rate (30fps) you see players travelling about 28cm in every frame. High-speed cameras it is doubled to about 60fps giving you about 13cm in each frame. My understanding (albeit limited) is that VAR uses high-speed replay. So, between one frame and the next, the foot can move 13cm. So, judgement for, say, an offside cannot be more accurate than 13cm. How can VAR be used to judge whether a toe is offside unless people had extraordinarily long toes?

Moreover, two players travelling in opposite directions will give twice the margin of error. And, if the foot is in movement as a result of kicking the ball, you might see 60m/s (which at high speed would be over a metre between frames). What am I missing here?

No offence mate, but my head's starting to hurt! 

If VAR, and all the discussions about it, are what football is now about (particularly cms here vs cms there, etc) then all the fun and excitement has gone. 

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55 minutes ago, Sciatika said:

Silly question...

A quick human can run at about 30km/h and possibly faster in short bursts. That is about 8m/s. At standard frame rate (30fps) you see players travelling about 28cm in every frame. High-speed cameras it is doubled to about 60fps giving you about 13cm in each frame. My understanding (albeit limited) is that VAR uses high-speed replay. So, between one frame and the next, the foot can move 13cm. So, judgement for, say, an offside cannot be more accurate than 13cm. How can VAR be used to judge whether a toe is offside unless people had extraordinarily long toes?

Moreover, two players travelling in opposite directions will give twice the margin of error. And, if the foot is in movement as a result of kicking the ball, you might see 60m/s (which at high speed would be over a metre between frames). What am I missing here?

Your missing Nothing. There is an element of guess work and error. In cricket this is allowed for by umpires call. So in he case of Giroud’s goal it would have stood as the Lino gave it and the offside marginal.

Not much complaint about the Giroud goal, that is a consistent decision with what has gone on this season. 
 

Never liked VAR. Maybe I would if it bailed us out a bit more. On balance we have suffered more than we have benefitted. In the Champions League we have really benefitted which for the conspiracy theorists might explain a lot!

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Ham   
1 hour ago, Sciatika said:

Silly question...

A quick human can run at about 30km/h and possibly faster in short bursts. That is about 8m/s. At standard frame rate (30fps) you see players travelling about 28cm in every frame. High-speed cameras it is doubled to about 60fps giving you about 13cm in each frame. My understanding (albeit limited) is that VAR uses high-speed replay. So, between one frame and the next, the foot can move 13cm. So, judgement for, say, an offside cannot be more accurate than 13cm. How can VAR be used to judge whether a toe is offside unless people had extraordinarily long toes?

Moreover, two players travelling in opposite directions will give twice the margin of error. And, if the foot is in movement as a result of kicking the ball, you might see 60m/s (which at high speed would be over a metre between frames). What am I missing here?

Spot on and when you factor in that someone has to very quickly manually freeze frame the picture at the very millisecond that the crosser contacted the ball there's even more margin for error.

On Monday we didn't even get to see whether the image was frozen at the right time. We still haven't seen crosser and Giroud in the same image. 

Edited by Ham

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7 hours ago, NoblyBobly said:

midfield three of Kova, Greilish and Kante would do me just fine.

Maybe I should have said previously holding midfielder - that's what we're missing. Forcing Kanté to sit deep wastes his talent, but it means that he and Kovacic are both best in a number 6 position, shuttling between defence and attack. Neither offer assists or goals, neither are comfortable or useful sitting in front of the defence.

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paulw66   
9 hours ago, NoblyBobly said:

Maybe madrid will give us Hazard back in exchange.

Not as far fetched as it may have sounded a couple of months ago........I think Real signed Hazard too late for him to be the star turn they wanted him to, and likewise, Hazard left it too late to go there. He's had a pretty awful first few months, and he turns 30 during next season. 

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paulw66   
9 hours ago, Droy was my hero said:

The trouble is fitness - Kante is 29 next month and missed quite a few games this season without ever dominating games as he has in the last 4 seasons at Chelsea and Leicester.  His sell-by date (to PSG) may have gone.

 

I don't think his age would prevent PSG paying silly money. We'd be mad not to take it too. 

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Jasonb   
12 minutes ago, paulw66 said:

Not as far fetched as it may have sounded a couple of months ago........I think Real signed Hazard too late for him to be the star turn they wanted him to, and likewise, Hazard left it too late to go there. He's had a pretty awful first few months, and he turns 30 during next season. 

I thought Hazard should have gone a season earlier and thought we were very fortunate to get such a high price for him.

I don't think we will get similarly get the same for Kante, think with his recurring injuries, age and being played in a position that does not suit him will reduce any fee we might get.

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paulw66   
14 minutes ago, Jasonb said:

I thought Hazard should have gone a season earlier and thought we were very fortunate to get such a high price for him.

I don't think we will get similarly get the same for Kante, think with his recurring injuries, age and being played in a position that does not suit him will reduce any fee we might get.

Playing in France, he can be saved for their 2 difficult league games a season, and then for the CL

As for the position argument, not that I agree with it, but they could then pick in whatever position they want! 

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3 hours ago, Sciatika said:

Silly question...

A quick human can run at about 30km/h and possibly faster in short bursts. That is about 8m/s. At standard frame rate (30fps) you see players travelling about 28cm in every frame. High-speed cameras it is doubled to about 60fps giving you about 13cm in each frame. My understanding (albeit limited) is that VAR uses high-speed replay. So, between one frame and the next, the foot can move 13cm. So, judgement for, say, an offside cannot be more accurate than 13cm. How can VAR be used to judge whether a toe is offside unless people had extraordinarily long toes?

Moreover, two players travelling in opposite directions will give twice the margin of error. And, if the foot is in movement as a result of kicking the ball, you might see 60m/s (which at high speed would be over a metre between frames). What am I missing here?

Good post. 
A technical discussion on velocities (small because I find it fascinating, but the chief Mod, MT, doesn't.):  30Km/h is optimistic - it is a good average speed over 100m, but the first 20m of that will be much slower.  Footballers are generally slowing down after 20m.  See the graph on page 6 here.  
On the other hand, bodies move at up to 30Km/h.  But one foot is still at any moment in time.  The other one must be doing close to 60km/h.
So my estimate would be running at 20Km/h, but feet moving at up to 35Km/h for a very similar 16cm per frame at 60fps
I can't imagine players moving in opposite direction as speed is common though.

Still 13 or 16cm is still less than the size of a Giroud boot.

2 hours ago, Super Kenny Monkou said:

Your missing Nothing. There is an element of guess work and error. In cricket this is allowed for by umpires call. So in the case of Giroud’s goal it would have stood as the Lino gave it and the offside marginal.

Not much complaint about the Giroud goal, that is a consistent decision with what has gone on this season. 

Never liked VAR. Maybe I would if it bailed us out a bit more. On balance we have suffered more than we have benefitted. In the Champions League we have really benefited which for the conspiracy theorists might explain a lot!

yes, yes, yes.  We always appear to do well in the CL (except of course against Barca who have every ref on their side whoever they play).
I think CL refs are basically a lot better than PL refs, as well as being a lot more honest  (waiting for their Barca Pay Day I guess).  

1 hour ago, Ham said:

Spot on and when you factor in that someone has to very quickly manually freeze frame the picture at the very millisecond that the crosser contacted the ball there's even more margin for error.

 

So No and Yes.
The foot striking the ball is also moving (I'd estimate) at about  10-16cm per frame+ (1 frame = 17 milliseconds).  I think it should be easy to get this moment correct to within 1 frame.

 

So there are 3 potential errors:

  • The moment the ball is passed  - lets say +/- 1 frame
  • The measured gap between striker and defender - I suspect modern technology and a proper preparation makes this <= 2cm
  • Any mismatch between the frame count on one camera and the other - which could be multiple frames or might always be zero
     
  • and the velocity of the attacker might be 16cm per frame.

With perfect synchronisation, that means a maximum error of 16+2 = 18 cm.

With imperfect synchronisation, it could be 50cm - half a metre.

3 hours ago, Ham said:

On Monday we didn't even get to see whether the image was frozen at the right time. We still haven't seen crosser and Giroud in the same image. 

Indeed.  What I don't understand is if the 2 cameras are perfectly synchronised (and they might be) then we should see a synchronised double shot of both passer and man offside together.  It ought to be really easy, with "Rock and Roll" as the cricket people say, showing the frames before and after.
Has anyone seen this (I don't watch much non-Chelsea football)?  The absence is very suspicious.  

The cricket comparison is good here.
They have 3 big advantages:  There has always been a recognition that umpires just do their best and that errors are inevitable.  There is no "should I call it now or play on issue (they have a natural break in the game and no "should I let play go on" to worry about). And VAR is not introducing new rules or interpretations* or creating a difference in how the game is umpired between VAR games and non-VAR games.
But the big difference is that International cricket has long been accused of Umpire bias against Asian teams.  So they set the system up to directly prevent bias and demonstrate exactly how the decisions are made.
Football has always been in denial about bias, and the VAR system actually helps referees cover bias up rather than makes it clearer to the viewer.

*with the exception of umpires giving LBWs more confidently which is similar to refs giving closer offside calls.

 

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21 minutes ago, Droy was my hero said:

Good post. 
A technical discussion on velocities (small because I find it fascinating, but the chief Mod, MT, doesn't.):  30Km/h is optimistic - it is a good average speed over 100m, but the first 20m of that will be much slower.  Footballers are generally slowing down after 20m.  See the graph on page 6 here.  
On the other hand, bodies move at up to 30Km/h.  But one foot is still at any moment in time.  The other one must be doing close to 60km/h.
So my estimate would be running at 20Km/h, but feet moving at up to 35Km/h for a very similar 16cm per frame at 60fps
I can't imagine players moving in opposite direction as speed is common though.

Still 13 or 16cm is still less than the size of a Giroud boot.

yes, yes, yes.  We always appear to do well in the CL (except of course against Barca who have every ref on their side whoever they play).
I think CL refs are basically a lot better than PL refs, as well as being a lot more honest  (waiting for their Barca Pay Day I guess).  

So No and Yes.
The foot striking the ball is also moving (I'd estimate) at about  10-16cm per frame+ (1 frame = 17 milliseconds).  I think it should be easy to get this moment correct to within 1 frame.

 

So there are 3 potential errors:

  • The moment the ball is passed  - lets say +/- 1 frame
  • The measured gap between striker and defender - I suspect modern technology and a proper preparation makes this <= 2cm
  • Any mismatch between the frame count on one camera and the other - which could be multiple frames or might always be zero
     
  • and the velocity of the attacker might be 16cm per frame.

With perfect synchronisation, that means a maximum error of 16+2 = 18 cm.

With imperfect synchronisation, it could be 50cm - half a metre.

Indeed.  What I don't understand is if the 2 cameras are perfectly synchronised (and they might be) then we should see a synchronised double shot of both passer and man offside together.  It ought to be really easy, with "Rock and Roll" as the cricket people say, showing the frames before and after.
Has anyone seen this (I don't watch much non-Chelsea football)?  The absence is very suspicious.  

The cricket comparison is good here.
They have 3 big advantages:  There has always been a recognition that umpires just do their best and that errors are inevitable.  There is no "should I call it now or play on issue (they have a natural break in the game and no "should I let play go on" to worry about). And VAR is not introducing new rules or interpretations* or creating a difference in how the game is umpired between VAR games and non-VAR games.
But the big difference is that International cricket has long been accused of Umpire bias against Asian teams.  So they set the system up to directly prevent bias and demonstrate exactly how the decisions are made.
Football has always been in denial about bias, and the VAR system actually helps referees cover bias up rather than makes it clearer to the viewer.

*with the exception of umpires giving LBWs more confidently which is similar to refs giving closer offside calls.

 

DRS has been greatly improved cricket and made the game better. VAR needs to do the same or scrap it.

Or alternatively give us a decision when we need it! I will be happy then!

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