questions

[dipperhitter]

Brian,

As a coach I'm fascinated to read about your work, as it seems you have developed technology that goes beyond regular video, maybe way beyond. But my question is as to the pro models. I believe you have stated that you have studied college players. Currently I am using dartfish and am able to pull in clips from Tennisplayer and other sources to look side by side. What do you feel about the differences if any between this and what you are doing? Is there a reason why you haven't filmed pros or is that too difficult using (I believe) the several cameras you probably use for 3D. But what if you are missing things in the measurments that you might get from Roddick or Federer? Also at what point is the measurement overkill? I mean can a great coach eyeball certain things or...? Thanks for the work you are doing and for taking the time to consider these questions. I hope they don't seem too pushy.



DH

[BrianGordon]

DH-

To start, I think the use of video by this site is excellent. Video in general, and Dartfish in particular are valuable coaching tools and a lot of fun to play with. But while video and 3-D measurement are both observational tools, that is where the similarity ends.

I described in some detail the information that can be obtained through 3-D analysis in my articles and think the difference with video and video editing software is obvious.

My goal is, through basic and applied research, to understand the physical and biological mechanisms of executing Tennis strokes - then to teach the coaches how these mechanisms work – then give them the tools to assess how their players utilize these mechanisms, or not (through the computer interface).

To understand the mechanisms, I quantify the strokes of the best players I can find. The reason I have not done this with world class players is that I’ve never had the opportunity to do so. 3-D measurement is a very complicated process always, but access is the main reason. Certainly that data would provide valuable information to my learning process.

But your first question is one I’m often asked. I’ll use an analogy:
If one goes to the doctor with knee pain the doc would make a decision based on observation, manipulation, and experience as to the source of the problem (the dartfish approach). The doctor may also order an imaging modality such as a MRI to obtain a deeper understanding of the problem (the 3-D approach).

So the difference between what you do with dartfish and what I do with 3-D is really just a matter of level of detail. You (I’m assuming here) would point to the technique of a pro and ask a student to emulate it based on your experience and the pro’s success in using it.

I might ask to student to emulate portions of it if I understood the mechanical (velocity, acceleration, force, torque, muscle contractile benefit, etc.) repercussions, and determine that current technique does not provide equivalent conditions, and conclude the student was capable of implementing the technique component.

Is it overkill? Perhaps to some – but I want the MRI when my knee hurts. In my opinion, one can’t have too much information. However, the main resistance to using 3-D is the time and effort of coaches to gain the knowledge about, and interpret the information. I can understand this point of view but can’t accept it in my own work.

Finally, certainly some of the things I measure can be seen without 3-D measurement (by a qualified coach). My process (I believe) clarifies the information however. Something as basic as a joint angle can be interpreted very differently via direct observation and 2-D video with a less than optimal viewpoint. But my system attempts to incorporate measurement AND understanding on a deeper level, which carries over to direct observation.

I’m sure you are a great coach, but if we sat down and observed the same player executing the same stroke I believe we would come to very different conclusions about what is happening and what to do about it. Which opinion is more advantageous to the player is open to the Tennis world to ultimately decide.

Thanks for the excellent questions, and sorry it took so long to reply but I was on the court all weekend - Brian