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Do you unweight on the steeps? - Page 2

post #31 of 87
Quote:
Originally posted by Bob.Peters:
Do any of you guys ever watch World Cup GS or Slalom races?

There's a TON of unweighting going on there. Still. In 2003. Even with the newest skis.

Do any of you ever ski things that are 40-degrees plus, about two ski-lengths wide, with rock walls, trees, moguls, or other unpleasantness below or to the sides?

There's a ton of unweighting going on there as well.

I'm sorry, but anyone who tells me they don't unweight is going to have to show me how to survive some of these situations without unweighting.

Bob
Bob: Obviously you're still turning too much! (HA! HA!) Just kidding.
post #32 of 87
So the answer is in a chute due to minimal width available to turn un-weighting is required. On a steep slope where the width allows a reasonable “turn” un-weighting i.e. lifting the skis off the snow is not required. Does that about sum it up with the exception of crud snow? I just returned from Big Sky where I found on the steeps all of the above was required depending on time of day and width or breadth of the run. The answer is yes and well no!

Also I avoid the use of the term rising with un-weighting. When you equate the two terms skiers stand up instead of moving forward with their center of mass. Racers are moving forward and across their feet with their hips allowing the skis to release and not rising. In fact Bode Miller does move lateral as in a “pedal” turn and then “pulls” his skis back under and around as his body moves downhill, which is one reason he is so successful with the "modern" skis when the course is set up for very round turns. He also uses an diverged (open)tip with one ski if he is too hot into the turn. (Now if he could only gain balance but whom that is another topic!) [img]graemlins/thumbsup.gif[/img]
post #33 of 87
Quote:
Originally posted by Prosper:
Are my skis unweighted while I'm sliding down a steep, narrow chute on my back?
No, but they are when you are sliding down a steep icy chute face first on your stomach.
post #34 of 87
Diggin' up an old one! Great photos Bob. But if you look closely at your pictures they show the same thing mine does. As I mentioned the C.O.M. is the 3-dimensional balance point of an object. If you put a ski on edge and turn it across your line-of-motion, pressure or what's perceived as weight is created. Do you agree with that? If you do then you should also agree that you can turn a ski and not create a change of direction. With the shapes of skis these days, a self steering effect is built into the ski so it is very difficult, if not impossible, to put a ski on edge and not get a change of direction. Do you agree with that? If you do then you should agree with the statement that I made about forces that act upon your C.O.M. are felt through your B.O.S. (the feet being light and heavy) To flatten your skis the B.O.S. needs to be under the C.O.M., as all of your photos and mine show so you must agree with that, a release of pressure or "unweighting". I think what you missed from my explanation is this: Look at the photo that you posted by Ron LeMaster, the skiers C.O.M. is at it's lowest point when her joints are most extended(frame 1 just past the red gate), it's at it's highest point when her joints are most bent which coincedentally happens to be when her feet or B.O.S. is directly under her C.O.M. and her skis are flat(frame 5) I agree with your statement that
Quote:
"Rising"(extending)does not cause edge release-flattening the skis on the snow does
What I was saying is flattening the skis on the snow raises the mass not that you extend to raise the mass to flatten the skis. I guess maybe it's just how you interpret "rising". I don't think of extension as rising, as I said it actually lowers the mass. Try this simple experiment; hold your ski pole just under the basket, the basket is the B.O.S, the grip is the C.O.M. Tip the pole from side to side, the grip rises and is at it highest point when the basket is parallel to the ground or, flat. The pole length remains the same. As the picture of Sarah Schleper shows, the leg length doesn't change much but the C.O.M. does and HAS to rise to change edges.

[ April 18, 2003, 01:20 PM: Message edited by: Ski Professor ]
post #35 of 87
Quote:
So the answer is in a chute due to minimal width available to turn un-weighting is required. On a steep slope where the width allows a reasonable “turn” un-weighting i.e. lifting the skis off the snow is not required. Does that about sum it up with the exception of crud snow?
Hi Learner--

You've pretty well summed up what usually DOES happen, but it really is not what MUST happen. Even in a steep, very narrow chute, it is not necessary to unweight the skis in order to turn them, even 180 degrees--provided you are willing to let them run downhill a little during the turn. Think of the basic "hockey stop." While many skiers like to make a little hop to unweight their skis in hockey stops, all that is really necessary is to flatten them and pivot them with your legs. Properly done, "pivot slips" involve 180 degree pivoting too, and DO NOT require any vertical motion or elimination of your full weight bearing on the skis.

There are two reasons why most skiers hop (up-unweight) when they pivot their skis in steep, narrow chutes. One, which you've mentioned, is that the snow is often soft and cruddy, so simply flattening the skis does not actually release the snow's grip--you have to get them up out of it. The other is that many skiers are NOT willing to release their edges and let their skis run downhill in these steep, intimidating situations. So they hop straight up in the air, pivot their skis 180 degrees, and land on edge with minimal travel down the hill. But it is, technically, possible to release the edges and pivot the flat skis 180 degrees within their own length, without removing the force of your full weight from them. So it is technically possible to ski even a steep, very narrow chute without unweighting.

Once again, I must emphasize the difference between "unweighting" and the simple reduction of pressure that results from flattening the skis and ending a turn. "Weight" is the force produced by gravity pulling your body down onto the snow. If you weigh 150 pounds, then there is 150 pounds of force pressing down on your skis when you just stand still. You can reduce or eliminate that force--momentarily--by hopping up in the air or dropping down suddenly ("active unweighting") or by being launched from a bump or rebounding out of a turn ("passive unweighting"). This reduction/elimination of the force of your WEIGHT is what is meant by classic "unweighting," and it is how I have been using the term in this discussion.

Gravity, of course, is not the only force involved in turns. The actual CAUSE of turns is "centripetal force," which can be simply defined as "any force that causes a turn" (more precisely, any force that causes something to move in a circular arc). Gravity can and does provide a component of centripetal force as it pulls us down the hill, into the turn, in the first half of a turn. The sideways push of the snow against tipped skis, into the turn, provides the other main component of centripetal force in skiing.

As Ski Professor suggests, we sense both "weight" and centripetal force as pressure on the bottoms of our feet. When we flatten our skis, the snow can no longer push sideways on them, so that component of centripetal force vanishes. The pressure we feel on the soles of our feet diminishes. But if that's ALL we do--flatten the skis, without any of the "unweighting" criteria I described above--the force/pressure of our full body weight will remain on them. This reduction of pressure that results from just flattening the skis/releasing their edges/ending the turn does NOT fit the definition of "unweighting." Again, recall the analogy of the car in S curves that I described earlier in this thread. When a turn ends, centripetal force ends (by definition). But the car's full weight remains pressing down on the road, unless a frost heave or something "unweights" it.

SO.... Anyone who insists that ANY reduction of the pressure on the skis should be called "unweighting" would be correct that unweighting occurs in the transition between all turns. "Pressure" is another name for the very force (centripetal) that CAUSES the turn, so of course, when the turn ends, so does that pressure.

But I maintain that, as long as my full weight remains on my skis, I have NOT "unweighted" them, no matter how much I may have reduced other forces/pressures. By this definition, "unweighting" is clearly NOT necessary in all turns!

It seems quite counter-intuitive to define "unweighting" any other way, doesn't it? How can anyone suggest that you have unweighted your skis, when you still have your full body weight on them? In any case, whether you agree with this statement or not, the classic definition of "unweighting" on skis is as I've described it. See THE HANDBOOK OF SKIING, the classic "skier's Bible" by Karl Gamma: "Unweighting:The process by which a skier momentarily reduces the presure that his body weight exerts on his skis." (emphasis mine). End of argument!

Expert skiers are fully capable of controlling these two distinct phenomena independently. They can flatten their skis, eliminating centripetal force, with or without unweighting them, at will, as appropriate, on any terrain or snow condition including moguls. With skillful flexing and extending movements, they can momentarily reduce, or increase, the pressure on their skis at any point in or between turns, independently of the tipping or flattening of their skis, and independently of the other forces acting on them.

It is for this reason that we MUST NOT confuse "extending" with "releasing the edges." It is unfortunately common jargonistic ski instructor dogma to insist that skiers "extend to release the edges" when they really mean "flatten the skis to release the edges." You can flatten your skis with or without extending, and you can extend with or without flattening your skis. By insisting that skiers extend to release their edges, we may force them to unweight unnecessarily and inappropriately, when all they really need to do is flatten their skis on the snow.

I've rambled long enough. Just thought it would make sense to revisit some of these issues that keep resurfacing.

Best regards,
Bob Barnes
post #36 of 87
Hi Ski Professor--

Thanks for digging this one up again. While it's pretty technical, this discussion involves some very important concepts, including some common misconceptions that cause many skiers unnecessary problems!

While we probably agree on "the forest," I think we're seeing "the trees" a little differently. Here's my response to some of the points and questons you raise:

Quote:
If you put a ski on edge and turn it across your line-of-motion, pressure or what's perceived as weight is created. Do you agree with that?
Well, yes--if you pivot your skis crosswise to your direction of travel, and engage their edges, pressure you feel underfoot will increase. But regardless of how we may perceive it, this pressure is NOT the same thing as "weight." This movement does NOT cause us to gain weight!

Quote:
... you should also agree that you can turn a ski and not create a change of direction. With the shapes of skis these days, a self steering effect is built into the ski so it is very difficult, if not impossible, to put a ski on edge and not get a change of direction. Do you agree with that?
I agree with the first part--pivoting your skis without changing your direction of travel is the definition of a "hockey stop" or a "pivot slip." And I somewhat agree with the second part--doing it with NO change of direction is a tough test of skill, on ANY ski--as many instructor certification exam candidates have learned, to their chagrin. But it is certainly not impossible. Challenging, yes, impossible, no!

Quote:
If you do [agree with the previous statement] then you should agree with the statement that I made about forces that act upon your C.O.M. are felt through your B.O.S.
Not sure why this follows, but since I don't 100% agree with your previous statement anyway, it's a moot point. Yes, we feel many forces in skiing as pressure on the soles of our feet. No--as I've noted--not all those forces are "weight."

Quote:
To flatten your skis the B.O.S. needs to be under the C.O.M., as all of your photos and mine show so you must agree with that
No! Generally, flat skis coincide with the moment the CM (center of mass) crosses over the skis, and our photos do show this. But it is not necessary! Are you familiar with what Georges Joubert called "surf technique"? Just as angulation movements of the feet/ankles, knees, hips, and spine can increase edge angle at any point, so can they DECREASE edge angle. Whether I SHOULD or not may be debatable, but I CAN flatten my skis on the snow without my CM being over my feet.

Quote:
...a release of pressure or "unweighting".
As my reply to Learner above describes, while unweighting may involve a release of presure, not all releases of pressure constitute unweighting!

Anyway, I'm not sure any of these picky points is really critical to this discussion, beyond just defining terms, but since you've raised them, I've replied.

The real crux of our possible disagreement seems to be the following:

Quote:
What I was saying is flattening the skis on the snow raises the mass ... the C.O.M. does and HAS to rise to change edges.
As I've elaborated, the CM rising as the edges change is a common coincidence, but it is NOT a necessity. It often represents a common intermediate mistake! I can most certainly flatten my skis while LOWERING my CM, if I choose, by actively retracting (flexing, shortening) my legs beneath me as I tip my skis flat. I can flatten my skis while maintaining the heght of my CM too, and I can flatten my skis while raising my CM. As I noted in my reply to Learner, separating the movement pools of flexing/extending and tipping/flattening is a critical skill for expert skiing.

Your experiment of holding a ski pole at the bottom and tipping its grip left and right is flawed as an analogy of a skier--because that pole obviously CAN'T flex and extend as it tips, but a skier CAN. Unlike that pole, a skier's length need NOT "remain the same."

I contend that the sequence of Sarah Schleper shows the edge change without rising/unweighting as she demonstrates a "retraction turn." But if others don't see this, clearly all she would have to do is flex a little more deeply during the edge change in frame 5, and it would be obvious.

Accurate and independent movements of the CM relative to the feet, forward and back, left and right, and up and down, appropriate to the skier's desire and the task at hand, are a sign of expert skiing. Developing the skills to do this is hardly easy, and most skiers are not experts! But we must not confuse what most skiers DO with what MUST BE DONE. We must not confuse common practice with logical or physical necessity.

For sure, expert skiers routinely do things that most skiers cannot!

To summarize the relevance of these points to the original topic of this thread--unweighting IS often useful and often desirable, but it is NOT always necessary. Simply releasing the edges (flattening the skis) finishes a turn, releasing the pressure of centripetal force, but without a coinciding raising or lowering of the CM relative to the feet, it does NOT alter the pressure caused by the skier's body weight. Releasing the edges is not the same as unweighting!

Best regards,
Bob Barnes

PS--for those who REALLY want to get technical, consider that it actually makes no difference whether the CM is rising or dropping anyway, as far as "unweighting" goes. We can momentarily unweight--OR momentarily INCREASE the pressure on our skis--while rising OR sinking. What matters is not the direction of movement of the CM, but the direction of its ACCELERATION. Skis are unweighted when the CM accelerates downward--which means either slowing down an UP movement or speeding up a DOWN movement. And pressure increases when the CM accelerates upward. For what it's worth....
post #37 of 87
Good stuff guys. Just a couple things to add.

First, in reading the posts I did not see the idea of using extension as a means of INCREASING pressure (perhaps I missed it). At the end of a high force level carved turn the outside ski is the primary resistor of those forces (weight is concentrated on the outside ski). The outside leg is extended and the inside leg is flexed. A technique for making a rapid pressure transition to the new outside ski (the currently flexed inside leg) is to extend onto that leg which imposed immediate pressure on that ski and allows for quick edge engagement and thus quick turn initiation. As edge engagement takes hold centrifugal force takes over and drives the ski into reverse camber.

And finally some feedback on a couple of Bob's statements.

BOB SAYS:
I can most certainly flatten my skis while LOWERING my CM, if I choose, by actively retracting (flexing, shortening) my legs beneath me as I tip my skis flat.

FASTMAN REPLY:
True, but only to a point. There is a threshold in degree of edge being utilized in a turn where this is highly impractical, if not virtually impossible. In high speed high edge turns the CM is typically lowered very close to the snow if an effort to maintain a strong skeletal alignment to efficiently combat the forces created.

In such positions it would be very difficult, and not at all efficient to keep the CM at or below that elevation through the crossover at turn transition. The knees would have to be bent over 90 degrees. So bottom line, I think a qualifier on elevation of CM during the turn must be assigned to that statement to make it totally accurate.

BOB SAYS:
Simply releasing the edges (flattening the skis) finishes a turn, releasing the pressure of centripetal force, but without a coinciding raising or lowering of the CM relative to the feet, it does NOT alter the pressure caused by the skier's body weight.

FASTMAN REPLY:
Hmmmm. Are we forgetting the effect of the release of reverse camber as caused by the flattening of the ski? Maintaining a static CM (relative to the feet) at the end of a carved turn will allow the rebound of skis coming out of reverse camber to lower the pressure on the skis caused by the skier's body weight. This is one of the primary reasons skiers employ retraction, to help absorb that rebound energy and thus maintain better ski to snow contact and pressure.

[ April 19, 2003, 08:36 PM: Message edited by: FastMan ]
post #38 of 87
Quote:
In such positions it would be very difficult, and not at all efficient to keep the CM at or below that elevation through the crossover at turn transition. The knees would have to be bent over 90 degrees. So bottom line, I think a qualifier on elevation of CM during the turn must be assigned to that statement to make it totally accurate.
A valid point, FastMan, but it does not change the thrust of my argument. Surely you are right--depending on how "low" the skier gets at the lowest point, it could be difficult to stay that low through the crossover/transition without the flexibility of a limbo dancer. But three immediate responses come to mind. First, I have merely said that it is POSSIBLE, and that it is SOMETIMES preferable and efficient, to maintain pressure ("weight") on the skis through the transition. Quite often, as I've said, it is NOT preferable, and some unweighting makes sense.

Second, it is actually quite rare to see the CM so extremely low that, as you suggest, it would require abnormal contortion to keep it that low. Bending the knees more than 90 degrees is certainly not unusual!

Third, however "low" we get from inclining into a turn for balance, we get there progressively, as the forces develop. As we come out of the turn, the forces, and our inclination, diminish progressively. So we don't END a turn inclined way over, at least if we end it in balance! This does not contradict your point, of course, but it does suggest that even in the most radically inclined turns, even if the CM were to get so low that we couldn't physically cross over without raising it somewhat, there is still no need to SUDDENLY rise to initiate, so the unweighting effect could still be minimal if we so chose. The extreme inclination you describe is akin to a very large mogul where, no matter how much the skier tries to flex to absorb it, he will still be thrown into the air--but that would certainly not suggest that he shouldn't try for all he's worth to REDUCE the unweighting effect!

Quote:
Are we forgetting the effect of the release of reverse camber as caused by the flattening of the ski? Maintaining a static CM (relative to the feet) at the end of a carved turn will allow the rebound of skis coming out of reverse camber to lower the pressure on the skis caused by the skier's body weight. This is one of the primary reasons skiers employ retraction, to help absorb that rebound energy and thus maintain better ski to snow contact and pressure.
Well, I'm not forgetting it FastMan! I specifically mentioned rebound as one of the causes of unweighting, in my earlier post. You are right that rebound is one of the many things that affect pressure on skis, and that skiers must learn to harness for maximum efficiency and effect. Like going over a mogul or a roll, rebound can make unweighting effortless, if we let it, or it can require some effort and skill to absorb if we DON'T want to unweight.

At the same time, rebound is not what many people think it is, and excessive rebound often represents a mistake! As I mentioned above, in smoothly linked carved turns, skis tip AND UNTIP progressively, releasing the energy stored in the reverse-cambered skis smoothly. The rebound effect is minimal in such turns--by the end of the turn, the skier has returned to "neutral," and the reverse camber is gone! Even in slalom turns, where everything happens most quickly, this release of pressure CAN be smooth and progressive, with minimal rebound. In GS and longer turns, the release of energy stored in the skis can be downright slow! In the sequence of Sarah Schleper (page 1 of this thread), Sarah's edge angle, and the amount of pressure on and reverse camber of her skis, decreases smoothly throughout the first five frames. The rebound is minimal, like easing off the string of a bow, rather than letting it snap.

When skiers get "kicked" out of a turn, or pop up to initiate a turn, it is often a sign that they did NOT release the edge angle and forces of the turn smoothly. It is the signature of the "park and ride" skier who just plunks into a "position" and holds it throughout the turn, rather than moving progressively as the forces build and diminish. You have alluded to this problem with your statement, "Maintaining a static CM (relative to the feet) at the end of a carved turn will allow the rebound...," so I suspect we agree here. But this "static" pose is precisely the error that can be avoided by skillfully applied flexing-extending and tipping movements! Such skiers not only get popped by rebound, but they are also unable to shape their turns as they choose, because they fail to manage the constantly changing pressures of turns. They're passengers, rather than drivers.

Yes, this sport requires SKILL! Without it, skiers are VICTIMS of the same forces that experts master and harness to do their bidding.

Best regards,
Bob Barnes
post #39 of 87
Well done Bob! Given the opportunity to clarify his position and he does so EXPERTLY! It's refreshing to read posts that display such an understanding of the sport. I could only offer small details to suppliment your position, but it's really not necessary as you have covered this topic quite well. [img]graemlins/thumbsup.gif[/img]
post #40 of 87
Thanks FastMan! The respect is mutual. Please don't hesitate to add your details, fill in the blanks, or express a different perspective. We'll all learn!

Best regards,
Bob Barnes
post #41 of 87
Quote:
Originally posted by FastMan:
Well done Bob! Given the opportunity to clarify his position and he does so EXPERTLY! It's refreshing to read posts that display such an understanding of the sport. I could only offer small details to suppliment your position, but it's really not necessary as you have covered this topic quite well. [img]graemlins/thumbsup.gif[/img]
I agree with you FastMan, Bob has most definitely explained his point in great detail and at great length . Suffice it to say I have a differing opinion on some of Bob's points but do agree with others based on my experience. We seem to be saying the same thing although I'm saying it with a Canadian accent(it takes too long to type eh? at the end of every sentence, but trust me I'm saying it).
This being said I will add a couple more thoughts to defend/prove my point. As Bob says(paraphrased);the actual weight of a skier does not change in a turn, I'll add that it's the feeling of weight. I described this as pressure. No where did I say that weight is increased or for that matter, decreased. My point, and it seems to be Bob's point as well(?), is that the movement of the C.O.M. and B.O.S. affect pressure. As the C.O.M. moves to the inside of the B.O.S., the feet, the arc, the feet travel on an arc, yada, yada, yada, edge angle increases(in an every day parallel turn, sure you can surf a turn but why would you want/need to?)this increases pressure, the feeling of weight. When the B.O.S. crosses under the C.O.M. edge angle is reduced and pressure(not weight) decreases accordingly, this is most definitely true.
As I said, the C.O.M. is the 3-dimensional balance point of any object. To maintain balance while skiing movements must actually be 4-dimensional, fore-aft, lateral(my analogy of the ski pole tipping), rotational, and vertical. Bob's analogy of a hop describes this in a vertical sense although it is slightly flawed,(sorry, you said my anology was flawed, which it isn't, but based on your own explanations yours is)just because the skier is in the air he is NOT weightless. He has released pressure not weight, Bob said so, so it must be true I look at a hop in these terms, (and you should too!) While extending, pressure that is exerted into the snow will actually increase for a moment until the C.O.M. reaches inertia. At this point ALL pressure is released, the skier is airborne. Now, depending on what the skier does in terms of flexion when he lands can and will do two things. If he lands with his legs stiff there will be a moment of extreme pressure as the C.O.M. comes to an abrupt halt then pressure will return to normal. If the skier rapidly bends(drops the C.O.M. downward) he will absorb this pressure. If you want to think of this experiment in terms of weight try this; stand on a scale with your legs deeply bent and then extend rapidly, for a moment the scale will read an increase in weight. If you continue this rapid extension so that you leave the surface of the scale, obviously the scale will read 0 or "weightless". Did you lose any body mass? NO! What you actually did was release pressure Conversely, try this; stand on the scale with your legs straight and flex rapidly, for an instant the scale will show a reduction in weight until your C.O.M. reaches the bottom point of it's path and the reading will go back to your actual weight. Once again, did your body mass change? NO!
So in conclusion, maybe Bob and I are saying the same thing, I don't know but this is the way I understand "un-weighting" and use it on a daily basis while skiing and teaching. In my opinion to say that the C.O.M. does not rise and fall while skiing(turning) at any speed on any terrain is incorrect based on the information that I've just posted. This movement increases and decreases pressure in a 4-dimensional sense this same thing can be and is described as Weighting and Un-weighting. I know this because it's based on a component of a very well respected Interski presentation by Andre Schwarz and Martin Olson called Movement and Motion(I can name famous skiing guys too!).
It would be great to hook up with Mr. Bob Barnes/Colorado and discuss this further I think it would make for a few interesting chair rides. Maybe I'm a freak but it's this sort of stuff that I love about skiing. Thanks for the brain work out.

"And that's all I have to say about that." - Forrest Gump(not so famous ski guy)
post #42 of 87
I will admit I have not read all of this carefully, however, A quick glance at the photos leads me to think it isn't any sort of unweighting process and that particularly in the case of the first photos it is energy being managed.

Had flexion not occured the first skier in the Ski Professors photo would have exited stage left.

As Bob has alluded to, why do we term this unweighting in the first place?

Get to neutral .....then tip em!

P.S. I really wanted to say abduct the foot,plantarflex,invert, supinate, and abduct the inside femur but I didn't want to start a firestorm. Besides....it's time for more percocet balanced with a couple Red Bulls.

[ April 20, 2003, 06:12 PM: Message edited by: Rusty Guy ]
post #43 of 87
When it gets real steep and/or gooey snow, I make a stronger movement of mass down the hill (extension "up", but perpendicular to the tilt of the slope) to make darn sure I release, bending the new stance ski by "pedaling" with that extension...

When it's not as steep, or not as gooey, I can release the turn much easier, with just a tip of the ankles while relaxing the old "stance foot"...

But, if I go UP (vertical, not perpendicular to the slope) and UNWEIGHT (skis leave the snow) this is usually a "result of" not relaxing the old stance foot/leg enough so my center of mass moves down the hill over my feet... so I'll need to recover my balance when I make this mistake, and unweighting works.

If I am not perpendicular to the slope at release, I am NOT going to be in balance EARLY in the turn on the new stance foot... so I'll use a "recovery move", unweight to pop the
the edges loose so I can "catch up" with a rotary twirl IF that move is needed, you'll see me do a double pole plant with it... Stabilize me now!

I keep working on keeping the skis on the snow, BENT and TURNING, no matter what, it feels more secure... [img]smile.gif[/img] It's also a lot less work!
post #44 of 87
Bob

Would you care to comment on the eqipment, techniques etc, used to produce these stunning images? Great teaching and coaching tool, I would think.
post #45 of 87
Hi Arcadie--

These photo sequences and animations aren't as difficult as they may look. It's easier to do, probably, than to explain, but I'll give it a shot.

They're done with photo-editing software--like Adobe Photoshop or, in my case, Corel Photopaint. It takes a little practice and patience, but basically it's a cut-and-paste operation. The original images come from a digital video camera or from any high-speed sequence of photographs. Most of my sequences are 5 or 6 frames per second, from a video camera (every 5th or 6th frame of 30 frame-per-second video). Of course, you have to be able to capture the frames from the camera to your computer, but most video-editing software can do that easily.

To produce the montage, I just paste the first image of the sequence into a large, blank, new document. Then I mask out the part of the background of the second image that would cover the skier in the first image, and paste the new image on top of the first. I repeat the process for each successive image in the sequence. To make sure each image registers in exactly the right place, I align some stationary feature in the background that appears in both images.

That's essentially it. Sometimes it's easier than others, mostly depending on the background. If the background is simple, primarily white snow, with good contrast from the skier (that is, the skier isn't wearing white), most good photo editing software can mask the background out very easily, making cut and paste a snap. If you have to cut out the background by hand, it takes a lot longer. There is software that can help mask (Corel Knockout, for one), but I haven't experimented with it.

The animations aren't much harder--all you have to do is save each intermediate step of the finished montage as a separate file, then assemble them in an animation (.avi, .mov, or .gif) file. Photopaint has a very simple "movie" function that makes this easy.

It takes some experimenting, and you definitely get better and quicker at it with practice, but it is still time consuming. There are easier ways, though. "Dartfish" is a new state-of-the-art software program that automates the process. You've seen it--the networks called it "Stro-Motion" or something like that, and used it to produce instant montages, especially of the figure skaters, in the Olympic coverage last year. Dartfish is also the software that produced those cool superimposed video images of two ski racers in the course at once.

I hope this is helpful. I'd love to see some more photosequences here, because I agree--they're excellent learning tools, in addition to being fun to look at. Give it a shot, and let me know if I can help. There are little tricks that you will learn as you experiment, and I'd be interested to hear anything anyone else comes up with that helps. Good luck!

Best regards,
Bob Barnes

PS--a few notes on the finer details:

Obviously, the better the original images, the better the result. I know that some of Ron LeMaster's sequences come from a digital video camera, like mine, and others come from scanned images from motor-driven film cameras. He may also use a digital still camera these days, but I'm not sure. Few digital still cameras can shoot fast enough to create these high speed sequences, except for very expensive high-end digital SLR's (Nikon D1H, for example).

If you use still images from a standard digital video camera, they must "de-interlaced" to eliminate the inherent jaggy, fuzzy effect. One frame of video actually contains two superimposed images 1/30 second apart, with each image occupying every other scan line. "De-interlacing," which Photoshop or Photopaint can do with a simple mouse click, eliminates every other line and replaces it with a new one interpolated from the lines above and below, vastly sharpening the image.

Video shot in "progressive scan" mode is not interlaced, and produces much better still images than standard video. Only higher-end consumer video cameras have this mode, though, and, while it produces great stills, it's a lousy mode for video. Essentially, progressive scan video shoots with twice as much resolution per frame (because it's not interlaced), but at only half the frame rate, so it's jerky. My Sony TRV-900 can shoot in progressive scan mode, and that's what I used for the slalom animations in this thread, but the montage of David Oliver came from normal, interlaced video.

Again, I hope this helps!

[ April 20, 2003, 10:18 PM: Message edited by: Bob Barnes/Colorado ]
post #46 of 87
Quote:
Originally posted by FlipFlopFly:
With my old straight skis, several years ago, I use to; I would think we all did. However, now with shaped skis, it's just roll the ankles and keep motoring....I meen skiing.
Unweighting is the essence of good skiing. It is graceful and allows you to work with gravity. This is why I still use my old straight skis, and will always unweight everywhere except the bumps.

Unweighting is like small government. They are both commonsense, and they are both beautiful.
post #47 of 87
Agressive unweighting where it's not necessary is ugly , making people look like jack rabbits. Watch an old ski movie and see all those people bobbing up and down (often in really ugly one piece's). No wonder people started filming snowboarders. Thank god skiing got rid of that for the most part. We've got much better flow now.

[ April 24, 2003, 09:48 AM: Message edited by: Tog ]
post #48 of 87
Quote:
Originally posted by Tog:
Agressive unweighting where it's not necessary is ugly , making people look like jack rabbits. Watch an old ski movie and see all those people bobbing up and down (often in really ugly one piece's). No wonder people started filming snowboarders. Thank god skiing got rid of that for the most part. We've got much better flow now.
Watch me ski and you will laugh perhaps. Then use my skis and you will hang you haughty head in shame, realizing that your skiing only got EASIER, and that your skill got WORSE.

Then you will see the beauty in the flow of my fore and aft unweighting. You will cry in shame and awe.
post #49 of 87
Hey MIM--if you ever want to replace those "old straight skis," give me a call. I've got a basement full of "like new" straight skis--slaloms, giant slaloms, and high-performance recreational skis, Elan, LaCroix, others, 198-210cm. All with bindings, top-of-the-line. They're a little dusty, but they'd love a good home. Unweight me!



[ April 25, 2003, 08:39 AM: Message edited by: Bob Barnes/Colorado ]
post #50 of 87
MIM,
I applaud your selflessness in taking on the unenviable role of being a lighthouse marking a rocky shoal most travelers of the learning to ski journey would do well to avoid. Were it not for a few brave souls such as yourself, we might lose track of the perils we have left behind and inadvertantly venture there again.

Deepest thanks for maintaining a referance point of calibration as to where we have been and do not wish to go again lest history repeat itself.
[img]graemlins/thumbsup.gif[/img]
post #51 of 87
Hey now, just hold on people, MM might be on to something here. I think you need to possess a wider range of skills to ride the skis he's on.

Most of us learned to ski on straight skis, and for those of us who refined our skills on those shapeless planks to the point of being able to carve quality turns the transition to shape ski was effortless and almost instantaneous. Why? Because we had already developed all the skills we needed to drive the new shapes on our old straights. We knew how to roll an edge and develop pressure. We knew how to balance the forces we created by moving the CM. We could already direct our point of pressure anywhere we wanted, laterally or fore/aft, as we desired. All we had to do when we got on our new shape skis was make the necessary body position changes to put us in the balance of forces sweet spot we were so familiar with.

But for us straight ski carvers we also had to learn a whole bunch of other skills. With straight skis our choice of carved turn radius was pretty limited so we had to develop other tricks to reduce the radius. We learned to do things such as pivot or steer prior to carve, to feather into a carve and to step post carve. These skills allowed us to create turn shapes the geometry of the ski would not, and we used them frequently.

Now with shape skis, possessing these supplemental skills is not as crucial an issue. It is quite possible to skip refinement of those additional skills and project an illusion of proficiency by simply developing a neophyte ability to ride the sidecut from start of turn to the finish. That ability to shortcut the way to advanced skiing is going to result in skiers brought up on shapes not having the refined skill repertoire of the old straight board masters. I would guess the transition from shapes to straights would be far more difficult for today's shape babies than the straight to shape was for us.

So rock on MM, God love ya. Can't say I'm going to join you because I'd rather drive a Lotus through hairpin curves than a Cadalac, but I've got to respect your spirit for trying!! [img]graemlins/thumbsup.gif[/img]

[ April 25, 2003, 09:04 PM: Message edited by: FastMan ]
post #52 of 87
I beg to differ. Even in the case of shaped skis, it's not the plane, it's the pilot.

I would like to see the evidence that supports the contention that a lousy skier can magically perform on shaped skis. The only people I know who can do that are great skiers. Many of them, like FastMan, earned their stripes in the days of longer, straighter skis, and did indeed transition to the shapes without a hiccup. It was the pilot that adapted.

I found the adaptation from straights to shapes was simplification. One can almost eliminate gross motor movements. But this implies that one has to develop fine motor movements: to let (allow) and not to make (force) is perhaps the hardest skill of all to learn, and I'm not just talking about skiing.

It's difficult for people making the transition from straights to shapes to settle down (because of force of habit) and it is difficult for people learning to ski on shapes to settle down (because they want control). Either way, it is not in a human's nature to "let the ski turn you." It is very much in a human's nature to do just the opposite. The equipment may evolve, but people are still people.

MM, snobbery in reverse is still snobbery. If you're a good skier on straights then good for you. It doesn't mean anything to me. Your experience is not mine. I can't possibly judge it relative to my experience. I can only wish that you have as much fun as I do skiing, and hope you would wish me the same.
post #53 of 87
Quote:
Originally posted by nolo:

I found the adaptation from straights to shapes was simplification. One can almost eliminate gross motor movements. But this implies that one has to develop fine motor movements: to let (allow) and not to make (force) is perhaps the hardest skill of all to learn, and I'm not just talking about skiing.

That's exactly right, but even on straight skis the best skiers developed the fine motor skills required to maintain control at high speeds. The difference is that modern skis perform in a way that allows skiers of average athletic ability to develop those subtle skills at reasonable speeds. Those lucky few who had already developed those skills were among the first and most enthusiatic proponents of shaped skis. The transition for them was very easy. Skiers who learned to depend exclusively on gross rotary movements and defensive techniques will need to learn new skills to get the most performance from the new skis.

John
post #54 of 87
Quote:
Then use my skis and you will hang you haughty head in shame, realizing that your skiing only got EASIER, and that your skill got WORSE. - MM
Well, I'm always willing to learn something but I know my skiing won't get easier by going back to straight 205's. I've tried it. As for skills getting worse? That doesn't seem to make any sense but since you know what you're talking about, I guess I'd better stick to my shape skis.

Quote:
Then you will see the beauty in the flow of my fore and aft unweighting. You will cry in shame and awe
Congrats on your pressure control skills, they're still useful on the new skis contrary to the "just stand in the middle" philosophy. I will admit that this was one of the things I most enjoyed about my last pair of straight Volkl P20sl 205's. Bend the tip and then slam the tail for rebound unweighting. That was fun but a lot of work. I must say I still like to watch old school slalom for the rythm they achieve but then they're w/cuppers.

Still you can do that fore/aft weight shift on shapes. In the moguls doing that it's a real blast getting air off each one.
I'll take the awesome feeling of pulling some real g's on a pair of shape skis though. Super high edge angles are not that hard to achieve at reasonable speeds on shapes and boot-out is real. On straights you'd have to be doing 40mph to get any type of high edge angle in a turn. Angular velocities in turns on shapes are just so much faster...that's why they're more fun.

Do you need shapes to have fun? No...
Do we need to go out in the freezing cold, sit on a chair 50 feet off the ground in the wind and go to the top of a mountain in winter...for Fun?

I've got the perfect transition shapes for you. A pair of Rossi 9X 9.9 gs skis in 191cm, and Volkl P40 F1 red/white 193cm. The rossis are soft but were their best gs ski until the current generation of 9x's that came out in 00/01. The Volkl's are much stiffer but a thing of beauty at speed. I'll sell both for cheap.

I'd did pass a farmhouse near Stratton, VT with a huge pile of straight skis set up like a huge haybale. A sacrifice perhaps?...
post #55 of 87
Thank you for explaining that passage, John. I quite agree with you: modern ski geometries put good skiing within the grasp of moderately gifted athletes, where the less-forgiving skis of the past were harder for average Joe Skier to master.

However, I would argue that the masses are NOT achieving skiing mastery in a greater percentage than previously, as many assume to be the case. What we have succeeded in doing is creating a faster track to intermediate skiing, but people are still stalling out here as they always have.
post #56 of 87
Quote:
Originally posted by nolo:

However, I would argue that the masses are NOT achieving skiing mastery in a greater percentage than previously, as many assume to be the case. What we have succeeded in doing is creating a faster track to intermediate skiing, but people are still stalling out here as they always have.[/QB]
==============================

See there Nolo, we weren't disagreeing after all!!

This is the same point I was making in my post. With the opportunity shape skis offer for skiers to experience carving much further down the skill development ladder many rungs are being bypassed. That "fast track to intermediate skiing" you speak of which in the past I've described as a "rush to carve" is producing skiers who are carving turns and projecting a vague image of advanced skiing, but in reality have significant leaks and holes in their technical foundations. What better recipe for development stagnation.

Straight or shape, the same core balance, edging, and rotary skills must be developed to achieve mastery in the sport, nothing has changed here so I would say your observation that skiers are not achieving mastery in any greater percentages than previously is spot on. You can dress up a whore but it doesn't make her a lady.

[ April 26, 2003, 05:28 PM: Message edited by: FastMan ]
post #57 of 87
It's been suggested in the Forums, a long time ago, that the new skis have merely created a new type of intermediate skier. It used to be that the slopes were filled with terminal intermediate skiers on the verge of disaster because they couldn't hold an edge to save their lives, on any snow condition. Now we have a mass of equally unskilled skiers who can do nothing BUT tip 'em and carve--can't shape a turn, can't feather a skid, can't adjust their lines, can't control their speed....

Of course, some of the new "short cut" teaching methodologies haven't helped, suggesting that anyone can be an expert skier in a day or two, and exploiting the natural turning ability of skis as an excuse to NOT teach people how to turn them.

No, the new skis are no substitute for classic skiing skills! "The more things change, the more they remain the same!"

Best regards,
Bob Barnes
post #58 of 87
Quote:
Originally posted by Tog:
[QUOTEDo you need shapes to have fun? No...
I have a good skiing buddy who refuses to ski on shape skis, and he can ski the steeps, bumps and off-piste with the best of them (for those of you who know Taos-Al's Run, The Cornice and the High Traverse). Watching him ski is pretty. He can turn both feet at the same time; uses simultaneous edge changes; keeps his center of mass moving down the hill; can go slow (if he wants to, but rarely does) rarely falls, and when he does, he laughs. Shaped skis have helped to improve my skiing, but I still can't keep up with my friend. Getting back with the original topic of this thread, he usually uses active leg retraction and sometimes hop turns on some steep and especially narrow terrain (survival?), so I guess he does unweight on the steeps.
post #59 of 87
Why does he refuse to use shape skis? He wants to compare himself with Glen Plake?
I would think he could rip even more with something a little newer.
post #60 of 87
Quote:
Originally posted by Tog:
Why does he refuse to use shape skis? He wants to compare himself with Glen Plake?
I would think he could rip even more with something a little newer.
Why do we go out of our way to ski expert runs when there is an easier way down?

Everybody can "rip even more" on a low angle groomer. You can "rip even more" on shaped skis? So what?

Besides, there's only one "advantage" that shaped skis give you; the abilty to make "train tracks" in the snow and feel the G-forces. If I want to feel the G's I'll go ride the "Gravitron" at my local carnival side show, which is exactly where shaped skis belong, maybe not because of performance, but because of mentality.

I for one, do not want my skiing to get easier. I want to be a better skier. I want to do it on my own.

Why climb a cliff when you could walk up the other side through the woods? Ask a rock climber why he does it, or a whitewater kayaker why he takes those risks. If you can't understand why downhill skiing became a popular recreational sport in the first place, by all means keep the "easier is better" attitude. If you can grasp what skiing is about you'll switch back. You'll have to.
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