Would you define takeoffs and landings by zero pressure or some middling value? Skaters vary as to how much they point their toes on takeoffs and landings. Yu-Na Kim's lutz and flip is aided by digging in the blade rather than the toe pick. Her pressure transition would be sharp while those using their toe pick would have a more gradual transition. When a ballet dancer is on her toes, isn't she more "in the air" than someone flat footed? How "in the air" is defined can vary by as much as half a turn.
Originally Posted by Mathman
Actually, the laws of physics provide a simpler answer. When a skater is in the air, measured vertical acceleration becomes essentially zero. The skater becomes weightless.
Originally Posted by ChrisH
How could we ever have a machine that gives you a 100% clear decision if you can't even find a large number of people who agree on how far the jumps actually rotate/what a wrong edge take off is?
Originally Posted by Joesitz
Petkevich tells us that the salchow and loop jump are in fact "half rotation" jumps. That the take off edge deepens to such an extent on the take off that by the time the skaters presses down on the toe pick to jump the blade has completed half a turn on the ice.
Many jump specialists (including coaches at my rink) disagree with Petkevich and say that the edge should not come round as far as half a turn but that the bend to jump should be much quicker to sto pthe edge coming round as much and that any twist or turn of the blade should only ever happen on the toe pick as the skater pushed up to jump.
So which of these two scenarios would the machine be programmed to allow for? The important question of defining the jumps such that a machine can say yes or no would have to be resolved before we ever get to the stage of developing the machine.
Did I ever say I didn't approve it ? Because I do.
Originally Posted by Joesitz
But in order to come up with a solution for a problem, one has to wonder how it's going to be accomplished, and the possible problems with a given approach. Isn't that what's being discussed here ?
IMHO, there's no doubt that technology can help with these skating issues, all I'm saying is: it won't be easy.
Going back to the proposal section, pressure sensors can be good, but I'm not too sure if the skaters would be happy with someone putting something in their boots.
But anyway, suppose we come up a system, how it would be used? In tennis, not all plays are defined by hawk eye. The umpire makes all the calls. If a player feels that the call was wrong, on either side of the court, then he or she can challenge it. The rules say that when you call the challenge, whatever shows on the screen is the final decision. Neither the umpire nor the player can challenge it. (That's why no one complains after the challenge)
How would that play out on figure skating ? Would ever jump of every skater be automatic analyzed? Would the skaters get to challenge the tech pannel decision and then he system would come to place?
Hummm, something to think about...
Wicked Yankee Girl
One way to set it up so that the machine can pass a jump if it's absolutely sure it is correct and force the judges to review film if the machine cannot absolutely assure it's OK. I think Joe's idea that this review film be simultaneously broadcast on the Jumbotron is a good one. It would both tell the audience something wasn't perfect and fill the time you're waiting for the review to be done with something other than with the ISU's old film clips of speed skaters and old performances.
That would be a plus over the current system, I think.
Currently judges seem to review more frequently & scrutinize more closely skaters with a reputation for downgrades, sometimes missing the occasional flutzes and underrotations of skaters who do not have that reputation because they do not review them.
I don't think complicated tools are really needed in figure skating. With a good camera angle it's not that difficult to see underrotations. Just nice camera angle is enough in most cases, IMO.
And would it really matter. Those who have their favorite skaters will never admit they underroated no matter what equipment is used to show it.
Who will direct the camera angle? I see a lot of competitions LIVE like the judges and Tech Panel do, but I contend if are looking at a jump from beginning to landing, and you are viewing from the side of the skater, a spectator, judge or panelist can not see an underrotation clearly unless there is some sort of jerky movement to make the jump look complete. A camera view from the rear of skater as he/she is landing the jump will easily show passable landings or underrotations.
Originally Posted by skateaug
Problem here is that the cameraman must take the tape of ALL the skaters. A special device would not be so cumbersome when in use and we will all see the perfect or imperfect jumps on the Jumbotrom.
To ask myself, will this happen? I will say NO for the same reasons that secret judging is used.
No matter where you place the camera(s), there will be a better viewing angle for some jumps than for others, because skaters can place jumps anywhere on the ice with any kind of approach they're capable of, for at least six different kinds of jumps.
Figure Skater Music Editor
Actually Skate Canada already has a computer program/system that does what you're talking about. I don't know what the program name is though. How do I know about it? At the end of our 2008 Skate Canada Adult Championship farewell banquet, one of my skater friends who competes in Adult Competitive in Canada and Masters at the ISU Adult Competition was having her program analyzed with the Skate Canada CPC tech and I saw how they could freeze every movement down to the nano second on the laptop to show where she was making mistakes. It was really cool. I didn't watch long to watch and didn't interupt because I wanted to get back to the competition rink to watch the StarSkate Nationals before driving back to Windsor, ON. It seems that Skate Canada has this program intergrated into the CPC marking system. And it's the reason, my spiral sequence was given a big fat Zero ( Let go of my second spiral position in the change edge way to early, so the whole thing was a nothing even though it looked nice to the eye.
Originally Posted by enlight78
At the rink. Again.
They were probably using Dartfish to review elements. It's not a cheap solution and you have to look at it in review in a specific way. If you look at coachesquiz.com or skatingjumpsecrets.com, Trevor Laak used Dartfish analysis on the elements he reviewed.
You can also se from Trevors site that skating jumps do not have the same rotation in the air as their name impries. ie. a single axel can be called ISU clean with only 1 rotation in the air. The foot actually does a 1/4 turn on take-off and landing can be up to 1/4 underrotated so that an outside edge can be acheived.
A double loop is usually 1 1/4 rotations in the air, 1/2 on the take off, 1/4 on landing, and this is the way it has been for a long time.
Pre-rotations on the ice are an arguable topic of discussion, but seldom discussed in skating boards. Many feel they are not all that important as is the skater's posture during the air turns and the jump landings within the limits permissable. That's just what I noticed, however, personally, I do see serious errors in wrong take-offs of any kind.
At the rink. Again.
How, then, would you generate the rotation if the jump didn't pre-rotate? From a physics standpoint, the rotation has to start on the ice in order to achieve anything more than one rotation.
Yeah! Lets get this party started.
I don't believe pre rotation is the problem. One can pre rotate a half-turn and still do a clean three turns in the are if they actually do 3.5 turns. I believe thats why a clean quad is so hard. Because it is really doing something between 4.25 and 4.5 revolutions. If you count the rotation on the ice. I thought the technical pannel starts when the blade leaves the ice so pre- rotations doesn't matter. You can pre-rotate three turns if that what helps you but it won't count a bit.