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Discussion Starter #1
Hello,

I have a question about court surface CPR/CPI and ball RPR data.

I think that the court and ball at IW and Miami are:
  • IW Plexipave (cat.3 medium)         Penn/ATP (Type 2)
  • Miami Laykold Cushion Plus (cat.3 medium)   Penn/ATP( Type 2)
Some tennis TV reports Court Pace Index (CPI), ex. IW CPI=30.0 (medium-slow) in 2016 and 27.3 (slow!) in 2017. Miami in 2016 was CPI=33.1 (medium-slow). Do you know who are calculating these CPI's ? I am aware that some people are calculating via # of ace but I guess it might be inaccurate as one needs some calibration according to player conditions.

I am aware that TV also reports CPI changing every day. I know the ITF technical booklet and equation in page 27 gives the Court Pace Rating (CPR) as a function of temperature. But data of these coefficients are not available and I am not able to calculate myself. Also table in page 29 shows nice chart as function of coefficient of friction (mu) and restitution (e).

I wanted to know the CPI of Miami this year, and would like to know if official data for CPR/CPI and ball's Relative Percentage Rebound (RPR) are available somewhere.

Thanks !
Rei
 

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Hello,

I have a question about court surface CPR/CPI and ball RPR data.

I think that the court and ball at IW and Miami are:
  • IW Plexipave (cat.3 medium)         Penn/ATP (Type 2)
  • Miami Laykold Cushion Plus (cat.3 medium)   Penn/ATP( Type 2)
Some tennis TV reports Court Pace Index (CPI), ex. IW CPI=30.0 (medium-slow) in 2016 and 27.3 (slow!) in 2017. Miami in 2016 was CPI=33.1 (medium-slow). Do you know who are calculating these CPI's ? I am aware that some people are calculating via # of ace but I guess it might be inaccurate as one needs some calibration according to player conditions.

I am aware that TV also reports CPI changing every day. I know the ITF technical booklet and equation in page 27 gives the Court Pace Rating (CPR) as a function of temperature. But data of these coefficients are not available and I am not able to calculate myself. Also table in page 29 shows nice chart as function of coefficient of friction (mu) and restitution (e).

I wanted to know the CPI of Miami this year, and would like to know if official data for CPR/CPI and ball's Relative Percentage Rebound (RPR) are available somewhere.

Thanks !
Rei
Data is provided by the guys behind the HE system. I doubt there is a methodology available somewhere but it must be based on bounce and the loss of speed after contact. Definitely not based on aces, even tho tennis abstract did a fine job with their model.

If you want to know the CPI for Miami this year, you'll have to wait to be released (Tennis TV or Tennis Channel). Since Paris 2016 they did that for every M1000/WTF, hopefully they'll continue.
 

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I've my own CPI figured out by running an algorithm that 'reads' the broadcast matches I record, not unlike a hawkeye system but immenesly cheaper of course. The only real cost actually being the time and effort put into it to create the algorithm.
 

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I've my own CPI figured out by running an algorithm that 'reads' the broadcast matches I record, not unlike a hawkeye system but immenesly cheaper of course. The only real cost actually being the time and effort put into it to create the algorithm.
You can do the same thing with 3d hawkeye replays, although they're not as common now (tennistv used to have them for every match). Worked well because the side angle was always in exactly the same position, no problems with cameras being at different distances/angles etc.
 

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Discussion Starter #6
Hello,

Tennis TV posted the CPI yesterday in their Twitter.

It looks Miami surface is getting faster every year since 2014, CPI=33.8 (2017), CPI=33.1 (2016), both medium-slow.
At Indian Wells, it was CPI=27.3 (2017, slow), CPI=30.0 (2016, medium-slow).
Indeed the court this year in IW was very slow, but I was a bit surprised as I had an impression that Miami is also rather slow (but not as slow as IW).
Maybe it was due to low temperature and high-humidity due to rain.
 
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