Relative difficulty of types of jumps: triples versus quads
- Thread starter Mathman
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- Joined
- Jun 21, 2003
For myself (leaving BoP to respond to the dare as he thinks best) I will explain what is off-putting about this discussion.
Poster A posts a picture of a skater with some red lines drawn over it and proclaims. "Here is indisputable proof that blah blah blah." This is simply a an untrue statement. It is not indisputable, We are disputing it on this very thread.
Poster B looks at the exact same picture with the exact same lines superimposed and says, "I see your picture and your red lines, but I dispute your conclusions."
Poster C (me) looks at the very same picture and says, "This evidence is not fully persuasive."
Poster A says, if you can't see what these red lines give indisputable proof of, then you are stupid and the judges are, too" In mathematics, such argumentation is called "proof by intimidation." Nobody wants ro be stupid, so I guess there is more in those red lines than my poor brain can appreciate.
(All of this is independent of whether the actual claim "blah blah, blah" is true or not.)
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- Joined
- Jun 21, 2003
There is one more factor that makes me hold back in forming conclusions from still photographs. A photograph is in reality a flat two-dimensional surface that uses photographic eye-brain tricks to suggest depth and three dimensionality. Painters did the same in the days before photography. This is actually quite a superb use of technique to fool the eye into seeing something that is not really there on the flat canvas. That's art, 
But if we draw straight lines on the surface of the canvas afterward, the depth perception is lost. The angle between the lines is not the angle in the three-D action.
@Tally T. You didn't need to delete your post just above this one. Good content.
But if we draw straight lines on the surface of the canvas afterward, the depth perception is lost. The angle between the lines is not the angle in the three-D action.
@Tally T. You didn't need to delete your post just above this one. Good content.
- Joined
- Jun 21, 2003
I'll give you a hint. It mentioned Yuzuru Hanyu.
I would first check if this body position really creates an "awkward" impression when in motion in real time.
Google can bring you heaps of "awkward figure skating pictures" where posters poke fun on "hilarious" faces and body positions in photos of jumping and spinning skaters. But this is not what GOE is awarded for.
- Joined
- Jun 21, 2003
True, the GOE bullets are quite specific, especially the negative ones. Still, it it not admirable technique when a skater's upper body gets out of synch with her feet, or when a skater tries to muscle up a jump anyway after mistiming the takeoff..
The video (not real time but slow motion) of this particular jump of Amber's (which started this whole unpleasant donnybrook) is posted above, posts #15 and #22. Not textbook to my eyes, but she got the job done.
The video (not real time but slow motion) of this particular jump of Amber's (which started this whole unpleasant donnybrook) is posted above, posts #15 and #22. Not textbook to my eyes, but she got the job done.
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- Joined
- Jun 21, 2003
Well, I've given my opinion and said my piece. Carry on, all.
(Although I can't resist mentioning, in regard to the flat earth, that I once published a paper in a serious math journal discussing models of the earth's surface as the real projective plane RP2. It even won a prize for mathematical expository writing. Peace.)
(Although I can't resist mentioning, in regard to the flat earth, that I once published a paper in a serious math journal discussing models of the earth's surface as the real projective plane RP2. It even won a prize for mathematical expository writing. Peace.)
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- Apr 23, 2018
Sorry, it was some time past 1.30 am and I was half asleep and I thought I dreamed it along with a different online discussion on... you don't want to know
So I will say it again TPTB could always consult their GOAT and his thesis, A feasibility study on utilization in figure skating by a wireless inertia sensor motion capture system.
They would never, of course.... but imagine the kerfuffling if some of them did
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- Apr 23, 2018
You know me too well, I didn't even mention a name! Just a GOAT...I'll give you a hint. It mentioned Yuzuru Hanyu.
I actually wanted to mention that you probably mentioned the said thesis... Good thing to remember about it time after timeTPTB could always consult their GOAT and his thesis, A feasibility study on utilization in figure skating by a wireless inertia sensor motion capture system.
They would never, of course.... but imagine the kerfuffling if some of them did
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- Apr 23, 2018
But of course!I actually wanted to mention that you probably mentioned the said thesis... Good thing to remember about it time after time
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- Jan 28, 2013
I saw an interview with an Olympic level judge once, and I recall him talking about GOE. According to him, the GOE bullets are informative in highlighting good and bad aspects of an element, but in real time, judges are not mentally ticking through the bullet point checklist. GOE is awarded on perceived quality based on the judges' experiences, and it is determined quickly.
My read on that is that they might think, "OK, that triple loop was performed satisfactorily, certainly not a failure, but I've definitely seen better. It had a standard entry, pretty good air, and a nice landing position but without a lot of speed or flair in or out, although I enjoyed the little hop she did as an exit transition. I'm giving that a +1. Another judge might go for bv or as high as +2, but that's also reasonable."
Yesterday I happened to come across this video, which seems at least tangentially (no pun intended) related to the discussion of skating jump rotation:
www.youtube.com
For a quicker summary, see https://www.scientificamerican.com/article/the-sat-problem-that-everybody-got-wrong/
I'm not math oriented enough to come up with any specific takeaways for skating. Just that the fact that the skater is rotating around their own axis and also traveling along a curved path at the same time is surely relevant. And interesting to note that the amount of rotation perceived is also dependent on where it is observed from (e.g., a camera), even more so if the camera is moving.
So even if we had instruments that could precisely measure the rotation of the blade (assuming that's how we want to define jump rotation), we would still need to account for both the curved path of travel (which inherently means that a backward-to-backward single jump along the same curve will inherently have less than 360 degrees -- lutz being an exception because it changes curve, at least in the traditional technique) and the point of observation and whether it also is moving.
In the absence of such instruments, use of video analysis can only be an approximation, and we know that the view from one angle does not always agree with that from a different angle. As @Mathman pointed out earlier, that's even more true if the camera is moving. Broadcast cameras often move. The tech panel's camera always stays at a fixed point although it will pan to follow the skater across the ice.
Still frames in isolation give even less information about the movement as a whole.
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I'm not math oriented enough to come up with any specific takeaways for skating. Just that the fact that the skater is rotating around their own axis and also traveling along a curved path at the same time is surely relevant. And interesting to note that the amount of rotation perceived is also dependent on where it is observed from (e.g., a camera), even more so if the camera is moving.
So even if we had instruments that could precisely measure the rotation of the blade (assuming that's how we want to define jump rotation), we would still need to account for both the curved path of travel (which inherently means that a backward-to-backward single jump along the same curve will inherently have less than 360 degrees -- lutz being an exception because it changes curve, at least in the traditional technique) and the point of observation and whether it also is moving.
In the absence of such instruments, use of video analysis can only be an approximation, and we know that the view from one angle does not always agree with that from a different angle. As @Mathman pointed out earlier, that's even more true if the camera is moving. Broadcast cameras often move. The tech panel's camera always stays at a fixed point although it will pan to follow the skater across the ice.
Still frames in isolation give even less information about the movement as a whole.
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- Joined
- Jun 21, 2003
It is really quite incredible that we clever apes cannot figure out a way to measure how many times something rotates. We have no problem in determining that the planet Jupiter achieves 67 rotations in the (earth) month of February (ISU designation 68<<) even though both Jupiter and Earth (the camera) are also independently going through all kinds of other relative motions. For that matter, we can do the same for exoplanets that are so far away tha we can barely detect them at all.
Yet Kaori Sakamoto’s triple flip utterly defeats our most diligent scientific exertions.
Yet Kaori Sakamoto’s triple flip utterly defeats our most diligent scientific exertions.
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Obviously they don't put sensors on Jupiter or the exoplanets themselves. So what techniques do they use to measure the rotations?
And are they measuring rotation with respect to a fixed point or to the orbit of the planet doing the rotating or to a point on earth, which is traveling?
Could similar techniques be used on a smaller scale to measure jump rotation? And if so, would it be cost effective to do so?
How precise does jump rotation measurement need to be? To the extent that fully rotated difficult jumps add huge amount to the scores and reductions in base value and GOE can therefore significantly affect results, yes, it is important.
But is the importance of a few degrees of jump rotation really the best measure of who skated best on a given occasion?
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- Jun 21, 2003
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