3D analysis

[julian]

The only problem

Absolutely.

The only problem is why it was NOT defined b before
The second problem is what is the defintion of HORIZONTAL in post #145.
Obviously the y axis is a LOUSY answer.
Or
A projection on y axis is a LOUSY answer as well.

 

[toly]

The only problem is why it was NOT defined b before

I'm sorry about that.

The second problem is what is the defintion of HORIZONTAL in post #145.

It is X component.

Obviously the y axis is a LOUSY answer.
Or
A projection on y axis is a LOUSY answer as well.

This I don't understand.

 

[julian]

I give UP

I'm sorry about that.

It is X component.


This I don't understand.

The y component is the LARGEST contribution the racket head speed.
See the paper of Landlinger quoted in the Elliot paper.
I really need a drink.
Please see one of TWO below:
Landlinger, J., Lindinger, S.J., Stöggl, T., Wagner, H. and Müller, E.
(2010a). Kinematic differences of elite and highperformance
tennis players in the cross court and down the
line forehand. Sports Biomechanics 9(4), 280-295.
Landlinger, J., Lindinger, S.J., Stöggl, T., Wagner, H. and Müller, E.
(2010b) Key factors and timing patterns in the tennis forehand
of different skill levels. Journal of Sports Science and Medicine
9, 643-651.

 

[sureshs]

toly posts after drinking too much vodka

 

[julian]

I do NOT make any comments about other people.

toly posts after drinking too much vodka

I do NOT make any comments about other people.
You will get me banned

 

[toly]

The y component is the LARGEST contribution the racket head speed.
See the paper of Landlinger quoted in the Elliot paper.
I really need a drink.
Please see one of TWO below:
Landlinger, J., Lindinger, S.J., Stöggl, T., Wagner, H. and Müller, E.
(2010a). Kinematic differences of elite and highperformance
tennis players in the cross court and down the
line forehand. Sports Biomechanics 9(4), 280-295.
Landlinger, J., Lindinger, S.J., Stöggl, T., Wagner, H. and Müller, E.
(2010b) Key factors and timing patterns in the tennis forehand
of different skill levels. Journal of Sports Science and Medicine
9, 643-651.

Did you watch the video https://www.youtube.com/watch?v=5MO-fDUwNzg with the title “Nadal Forehand Back Racquet Brushing Velocity Analysis (from tennisplayer.com video)”? So, the analysis has nothing to do with Y component.

 

[hawk eye]

This thread is like The Matrix part 4. Some scary stuff in here.

 

[toly]

toly posts after drinking too much vodka

Today is Sunday and according to Russian tradition I must …

 

[julian]

I disagree 100 %

Did you watch the video https://www.youtube.com/watch?v=5MO-fDUwNzg with the title “Nadal Forehand Back Racquet Brushing Velocity Analysis (from tennisplayer.com video)”? So, the analysis has nothing to do with Y component.

I disagree 100%
It looks like eliminating the Y component underestimates the racket head speed SIGNIFICANTLY

 

[julian]

Your analysis of post #145

Today is Sunday and according to Russian tradition I must …

Do you claim that the VERTICAL racket head speed of NADAL exceeds
90 miles per hour "around" the contact?
Do you know what would be the "TOTAL" speed if
you would take into account that Nadal provides some speed PERPENDICULAR
to the net?

 

[toly]

Do you claim that the VERTICAL racket head speed of NADAL exceeds
90 miles per hour "around" the contact?
Do you know what would be the "TOTAL" speed if
you would take into account that Nadal provides some speed PERPENDICULAR
to the net?

From this video I cannot measure Y component, but it obviously interfere with X and Z component measurements due to photo camera not optimum position. This affects both components and we still could compare them. Also, I can be wrong about JY video fps and not sure about absolute velocities magnitude. IMO, it is not very important.

 

[Chas Tennis]

.....................................
I want to analyze your Nadal forehand video, can I?

Sure. Sent a PM. If interested in a Nadal video, reply.

 

[sureshs]

I do NOT make any comments about other people.
You will get me banned

toly said he drank a lot of vodka on Russia Day and posted here

 

[GuyClinch]

I could have sworn Yandell said he didn't believe in the stretch shortening cycle.. Weird.

I believe in it though - Heath Waters had cool video of it up for a few years now..

 

[JohnYandell]

I believe in it as analyzed by people who have the tools to measure it and explain it--like Dr. Gordon. But I think the term is over used and misapplied.

I also think that compared to the problems I see in most rec tennis, it's the cherry on top of the whip cream.

 

[rkelley]

Hey John, if it wouldn't be too much trouble could you post your measurement of Del Potro's average topspin on the "hitting thru the ball" thread?

Thanks.

 

[sureshs]

Hey John, if it wouldn't be too much trouble could you post your measurement of Del Potro's average topspin on the "hitting thru the ball" thread?

Thanks.

2000


http://usatoday30.usatoday.com/LIFE/usaedition/2013-08-26-826-US-Open-DELPO-breakdown_ST_U.htm

 

[jmnk]

The y component is the LARGEST contribution the racket head speed.
See the paper of Landlinger quoted in the Elliot paper.
I really need a drink.
Please see one of TWO below:
Landlinger, J., Lindinger, S.J., Stöggl, T., Wagner, H. and Müller, E.
(2010a). Kinematic differences of elite and highperformance
tennis players in the cross court and down the
line forehand. Sports Biomechanics 9(4), 280-295.
Landlinger, J., Lindinger, S.J., Stöggl, T., Wagner, H. and Müller, E.
(2010b) Key factors and timing patterns in the tennis forehand
of different skill levels. Journal of Sports Science and Medicine
9, 643-651.

is there any site on the net that provides these articles? I mean I know I can find abstracts, or pay $$ to get the articles, but sometimes those papers are posted in pre-published format. Any ideas/

 

[julian]

Papers

is there any site on the net that provides these articles? I mean I know I can find abstracts, or pay $$ to get the articles, but sometimes those papers are posted in pre-published format. Any ideas/

1.The abstract contains E-mail addresses of authors
Sometimes they will send you an electronic version
2.Google on the title of the papers
3.Go through publications of nih
4.One of my old posts have some quotations plus figures
the thread has a word "accelaration" in the title
5.use www.ResearchGate.com
6.
http://www.jssm.org/vol9/n4/15/v9n4-15text.php

 

[Chas Tennis]

is there any site on the net that provides these articles? I mean I know I can find abstracts, or pay $$ to get the articles, but sometimes those papers are posted in pre-published format. Any ideas/

The National Center for Biotechnology Information (NCBI) lists many abstracts. Some are available as free full reports. If only abstracts are listed then the full report is offered for an excessive price such as $35.

NCBI PMC lists the free full reports. (PMC = free full reports)
Use the PMC search box -
http://www.ncbi.nlm.nih.gov/pmc/

Here is a search of reports on "tennis".
http://www.ncbi.nlm.nih.gov/pmc/?term=tennis

Example of free report - Biomechanics and Tennis, B. Elliott
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577481/

Bookmark the above NCBI links because they are cryptic and a little hard to find even after you are on the NCBI website.

I just found this and I guess that the availability of the above full free reports might stem from the following- if NIH funds the research it goes into the public access reports.
http://publicaccess.nih.gov/

Thanks for letting us look at the results of our tax money that was used for this research.

 

[julian]

Fps

From this video I cannot measure Y component, but it obviously interfere with X and Z component measurements due to photo camera not optimum position. This affects both components and we still could compare them. Also, I can be wrong about JY video fps and not sure about absolute velocities magnitude. IMO, it is not very important.

Where did quote FPS?
What is the numerical value?

 

[julian]

Vertical speed

Toly,
Do you claim that the VERTICAL racket head speed of NADAL exceeds
90 miles per hour "around" the contact?
Do you see how large is the value 90 miles per hour for the vertical speed?

 

[toly]

FPS is 500.
Let’s analyze Nadal favorite forehand.

My computer display shows 2D images with XZ coordinate system. Does it coincide with real XYZ? The camera is behind Nadal, but also very high from the ground. Thus photo camera catches 3D Y component and transfers it into 2D image Z component. Inevitably there is a lot of distortion with vertical (Z) component and much less with horizontal (X).
I “blame” JY for that, camera should be behind Nadal with distance 300’ and height 6’ then 2D images could correlate much well with reality.
In above picture we can see that the ball after impact moves up very fast, that is absurd. So, I can stabilize this motion to almost zero and remove 3D Y component from 2D Z component and get more real (less speed) racquet vertical speed.

BTW, there are TWU calculator data of 5000rpm forehand: racquet speed 120mph, ball speed 82mph with 4950rpm. To produce high RPM we really have to create a lot of RHS.

 

[julian]

120 miles per hour??????

FPS is 500.
Let’s analyze Nadal favorite forehand.

My computer display shows 2D images with XZ coordinate system. Does it coincide with real XYZ? The camera is behind Nadal, but also very high from the ground. Thus photo camera catches 3D Y component and transfers it into 2D image Z component. Inevitably there is a lot of distortion with vertical (Z) component and much less with horizontal (X).
I “blame” JY for that, camera should be behind Nadal with distance 300’ and height 6’ then 2D images could correlate much well with reality.
In above picture we can see that the ball after impact moves up very fast, that is absurd. So, I can stabilize this motion to almost zero and remove 3D Y component from 2D Z component and get more real (less speed) racquet vertical speed.

BTW, there are TWU calculator data of 5000rpm forehand: racquet speed 120mph, ball speed 82mph with 4950rpm. To produce high RPM we really have to create a lot of RHS.

How did you get/produce 120 miles per hour?

 

[sureshs]

How did you get/produce 120 miles per hour?

From TW University instructions:

Racquet tip speed: Example: 80 pros FH, 120 LeeD's FH, 65 college FH, 40 intermediate FH, or any speed depending on shot and player.

 

[julian]

120 miles per hour ????

From TW University instructions:

Racquet tip speed: Example: 80 pros FH, 120 LeeD's FH, 65 college FH, 40 intermediate FH, or any speed depending on shot and player.

You are NOT helping very much

 

[JohnYandell]

suresh has it correct above

 

[sureshs]

You are NOT helping very much

Well, I did tell you before that toly posts here after drinking too much vodka

 

[toly]

Well, I did tell you before that toly posts here after drinking too much vodka

Maybe TWU calculator designers were drunk as well?

 

[toly]

How did you get/produce 120 miles per hour?

It’s not me, you better ask Rod Cross and Co. :shock:

 

[sureshs]

It’s not me, you better ask Rod Cross and Co. :shock:

Did you put it in the number or not?

 

[toly]

Did you put it in the number or not?

TWU calculator did. I represented all input data in post 173. Go to TWU, insert all input data from my post and you will get corresponding 5000rpm. Then try to get 5000rpm deep FH with 80mph RHS. According to TWU calculator it’s impossible!!! :shock::shock::shock:

 

[sureshs]

I think the software put 120 there by default and toly just accepted it.

 

[toly]

I think the software put 120 there by default and toly just accepted it.

Again, can you play with TWU calculator and demonstrate deep 5000rpm FH with 80mph RHS. I bet you will miserably fail, sorry. Enough talking, do something.

 

[julian]

The BASIC FLAW of post#173

FPS is 500.
Let’s analyze Nadal favorite forehand.

My computer display shows 2D images with XZ coordinate system. Does it coincide with real XYZ? The camera is behind Nadal, but also very high from the ground. Thus photo camera catches 3D Y component and transfers it into 2D image Z component. Inevitably there is a lot of distortion with vertical (Z) component and much less with horizontal (X).
I “blame” JY for that, camera should be behind Nadal with distance 300’ and height 6’ then 2D images could correlate much well with reality.
In above picture we can see that the ball after impact moves up very fast, that is absurd. So, I can stabilize this motion to almost zero and remove 3D Y component from 2D Z component and get more real (less speed) racquet vertical speed.

BTW, there are TWU calculator data of 5000rpm forehand: racquet speed 120mph, ball speed 82mph with 4950rpm. To produce high RPM we really have to create a lot of RHS.

The basic flaw of the graph of post #173
The data around the contact point are NOT RELIABLE for the interval
starting from the contact point till the contact point plus 2-4 miliseconds.
The reason is that physics at the contact is completely different than
physics AT THE CONTACT

 

[sureshs]

The basic flaw of the graph of post #173
The data around the contact point are NOT RELIABLE for the interval
starting from the contact point till the contact point plus 2-4 miliseconds.
The reason is that physics at the contact is completely different than
physics AT THE CONTACT

Is it because it is in small case instead of upper case? Just kidding.

 

[julian]

"SANITY" checks

What I am trying to do is to provide some "SANITY" checks.
The expression comes from physics.
Examples are:
Is it possible for the vertical speed of the head of the racket to achieve 90 miles per hour?
What are data of post #173 compared to other data published/presented/"stolen" etc?
You may google for names like Ariel,Vic Braden,Knudson,Elliot
It makes ZERO sense to plug data into the TWE calculator BEFORE spending
one second looking at the DATA
PS It is true that Verdasco hit 117 miles per hour forehand two days ago.
But it does NOT mean that the VERTICAL speed of his forehand was OMG,
90 miles per hour.

 

[sureshs]

I had the analysis done once. I am not sure how to find the post. I calculated the vertical and horizontal speeds and how each change after impact.

 

[toly]

What I am trying to do is to provide some "SANITY" checks.
The expression comes from physics.
Examples are:
Is it possible for the vertical speed of the head of the racket to achieve 90 miles per hour?
What are data of post #173 compared to other data published/presented/"stolen" etc?
You may google for names like Ariel,Vic Braden,Knudson,Elliot
It makes ZERO sense to plug data into the TWE calculator BEFORE spending
one second looking at the DATA
PS It is true that Verdasco hit 117 miles per hour forehand two days ago.
But it does NOT mean that the VERTICAL speed of his forehand was OMG,
90 miles per hour.

I absolutely agree with you about 90mph vertical component and really appreciate that you pointed that out. I already tried to explain what wrong is with that in post 174. Definitely I must do something about this, but I don’t know how to do it properly. The horizontal component of the racquet's velocity, IMO, is practically OK. Next time I have to choose video more carefully.
Nevertheless, what is wrong with TWU calculator?

 

[toly]

I had the analysis done once. I am not sure how to find the post. I calculated the vertical and horizontal speeds and how each change after impact.

Where is 80mph 5000rpm FH?

 

[toly]

Sure. Sent a PM. If interested in a Nadal video, reply.

Chas Tennis, Thank you. What can you say about this http://youtu.be/NhSX1ozdlj8.
It appears that your video is very good for 2D analysis!!!

 

[julian]

You have limited choices

Where is 80mph 5000rpm FH?

Toly,
you have two options
1.try 70 miles per hour
2.try to to talk to a TW staff

Suresh does NOT work for TW,last time I check

 

[julian]

Contact point data

I absolutely agree with you about 90mph vertical component and really appreciate that you pointed that out. I already tried to explain what wrong is with that in post 174. Definitely I must do something about this, but I don’t know how to do it properly. The horizontal component of the racquet's velocity, IMO, is practically OK. Next time I have to choose video more carefully.
Nevertheless, what is wrong with TWU calculator?

If the contact point is "frame #11" all #10,11,12 and 13 data shoukd be disregarded

 

[julian]

Do u blame a video?

I do NOT understand the statement
"Next time I have to t choose video more carefully."
Do you mean that if you would analyze,say, a serve by Joe Schmoe
you can assain a meaning to the values close to the contact point?

 

[Chas Tennis]

Chas Tennis, Thank you. What can you say about this http://youtu.be/NhSX1ozdlj8.
It appears that your video is very good for 2D analysis!!!

That is a good video choice for 2 D. Horizontal and vertical are very close. It's telephoto so the magnification is probably pretty even throughout the frame. With telephoto, objects farther from the camera are at about the same scale - unlike wide-angle lenses or unknown lenses. I don't know what goes into calibrating and calculating the speed so I still would leave out "Velocity MPH" and put in "Relative Velocity," no units.

The racket is probably traveling at a considerable angle to the ball's trajectory maybe 30° ?. That angle does not show and could be misleading. I was surprised to see that the racket had more speed (in-H & V plane) before impact than the ball has after impact (in the H-V plane). That looks like a slice, there's a very distinct racket face angle at impact.

Interesting videos would be how the the racket contacts the ball using higher frames rates such as 420 fps and close ups, shoulder up, or hand up, etc. . To do it right might take higher frame rates such as 1000 fps. ? What is the forearm-racket angle at impact, β, for each type of serve?