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kallend

Different types of distortions

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Just so we are all talking about the same thing, I have created some pictures of various types of distortions, with the words I'm using to describe them.

For convenience, they are all based on a 49-way diamond having 90 degree corners to define the perfect formation. The same general idea would apply to any formation.

Picture 1. 49-way diamond. Each 4-way cell in the lattice is square.

Picture 2. UNIFORM distortion, stretched along the line of flight. All the cells in the lattice are the same shape and size, but no longer square. The diagonals of the diamond are still at 90 degrees to each other.

Picture 3. UNIFORM distortion, skewed (the diagonals of the diamond are no longer at 90 degrees to each other). All the cells are the same shape and size, but no longer square.

Picture 4. Smooth, continuous distortion but not uniform. What should be straight lines have become curves. 4-way cells in the lattice are no longer all the same shape and size.

Picture 5. Inhomogeneous (random) distortion. Each point is allowed to move up to 40% of the interjumper spacing. The formation is the right shape overall but no longer so "pretty" internally.

Picture 6. Inhomogeneous (random) distortion. Each point allowed to move up to 80% of the interjumper spacing. Formation is still generally the right shape overall, but very ugly internally.
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The only sure way to survive a canopy collision is not to have one.

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Pretty cool.
I think in general, the stetch is the only thing which can occur, even with perfect sightlines. Allowing a minimal scaling of the grid sideways (in/out) to conform the formation (within a certain limit, of a few %) seems reasonable. As it means you can have perfect spacing, flying and distances between each jumper, a formation thats as pretty as you'll ever see, yet a formation thats not 100% confirming to the planned dive.

All other forms of stretch and skew, seem like things that can be fixed by just keeping eyelines/rows in check during flying.
In short, all a result of bad flying, where-as the stretch can be good flying, yet just a misjudgement of a few degrees in terms of angle.
I think it would also only work, if its symatrical. Too extreme, asymetrical scaling (in short> looking like shit) to the point of visually spotting it instantly, should be a big no in my book.

Its just subtle angle tollerances Im interested in.
Lets chat more via mail on this after the FAI stuff, so we can ask Tom (our programmer) to maybe give this one a goB|

JC
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Pretty cool.
I think in general, the stetch is the only thing which can occur, even with perfect sightlines. Allowing a minimal scaling of the grid sideways (in/out) to conform the formation (within a certain limit, of a few %) seems reasonable. As it means you can have perfect spacing, flying and distances between each jumper, a formation thats as pretty as you'll ever see, yet a formation thats not 100% confirming to the planned dive.

All other forms of stretch and skew, seem like things that can be fixed by just keeping eyelines/rows in check during flying.
In short, all a result of bad flying, where-as the stretch can be good flying, yet just a misjudgement of a few degrees in terms of angle.
I think it would also only work, if its symatrical. Too extreme, asymetrical scaling (in short> looking like shit) to the point of visually spotting it instantly, should be a big no in my book.

Its just subtle angle tollerances Im interested in.
Lets chat more via mail on this after the FAI stuff, so we can ask Tom (our programmer) to maybe give this one a goB|



That's what I was thinking. A uniform stretch of a few % (not 100% for sure) still leaves a pretty formation, and we can then evaluate each jumper's position against that.
...

The only sure way to survive a canopy collision is not to have one.

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Within software, that could just be an easy thing.
Allowing the polkadot judging grid© to have the few % scale in/out automaticly, up to a certain degree.

Doing some fake photoshop formations, and asking for feedback with regards to 'wat goes and what doesnt' would again be a good thing, to find out which % of stretch would be acceptable..

Good stuff..
JC
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Within software, that could just be an easy thing.
Allowing the polkadot judging grid© to have the few % scale in/out automaticly, up to a certain degree.

Doing some fake photoshop formations, and asking for feedback with regards to 'wat goes and what doesnt' would again be a good thing, to find out which % of stretch would be acceptable..

Good stuff..



I can do that, but it would be valuable if some OTHER people came up with pictures too.
...

The only sure way to survive a canopy collision is not to have one.

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was just playing with tolerances and uniform skew/stretch as well as non uniform stretch last night



mmm... I'd love to see video of that!
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Pretty cool.
I think in general, the stetch is the only thing which can occur, even with perfect sightlines. Allowing a minimal scaling of the grid sideways (in/out) to conform the formation (within a certain limit, of a few %) seems reasonable. As it means you can have perfect spacing, flying and distances between each jumper, a formation thats as pretty as you'll ever see, yet a formation thats not 100% confirming to the planned dive.



So, for a starting point (and allowing later change in the light of experience) what amount of stretch (+ or -) do you think is a reasonable allowance? 10%? 25%?

For reference, the stretched diamond I posted earlier has been stretched 30% along the line of flight. I'd consider that not acceptable.
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The only sure way to survive a canopy collision is not to have one.

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IMO, 20% is fair. We tested various formations for accuracy (formations that have been submitted as records) and found as much as 25% tolerance was required. 10% seems too demanding for larger formations.



we need to take into account not just formation that have been submitted, but also the possibilities that we are allowing for future submissions.

while I'm not yet set on my numbers for this, one thing I find is that when you look at a tolerance, you need to always check what is the worst most distorted awful looking formation that you can come up with that still works within that tolerance. if that worst example still fits within the standards of what we wish to call a record, then the values are acceptable.
if not, then the values need to be decreased, even if a stricter standard no longer fits all currently ratified records.

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if not, then the values need to be decreased, even if a stricter standard no longer fits all currently ratified records.



It's pretty obvious that this is already the case. While there is good discussion here in the values, the question that next needs to be asked is "how good should a record be?" and find an answer via more dialog.
Other questions:
Should there be an "intermediate" and "Advanced" set of values as there is in other classes of competition?

Should there be a differing set of values for say, a 9 way vs a multiplane load?

Should all experience levels, formation sizes adhere to one standard?

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if not, then the values need to be decreased, even if a stricter standard no longer fits all currently ratified records.



It's pretty obvious that this is already the case. While there is good discussion here in the values, the question that next needs to be asked is "how good should a record be?" and find an answer via more dialog.
Other questions:
Should there be an "intermediate" and "Advanced" set of values as there is in other classes of competition?

Should there be a differing set of values for say, a 9 way vs a multiplane load?

Should all experience levels, formation sizes adhere to one standard?



Good questions, and questions that can only be answered by judgment. Measurements can give accurate values, but interpreting those as pass/fail is a matter for the community to decide.

I'm inclined towards the 10% overall distortion as a maximum (both Summerfest 25-way and Elsinore 68-way were distorted overall by much less than this. 10% is quite achievable.
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The only sure way to survive a canopy collision is not to have one.

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Pretty cool.
I think in general, the stretch is the only thing which can occur, even with perfect sightlines. Allowing a minimal scaling of the grid sideways (in/out) to conform the formation (within a certain limit, of a few %) seems reasonable. As it means you can have perfect spacing, flying and distances between each jumper, a formation that's as pretty as you'll ever see, yet a formation that's not 100% confirming to the planned dive.

So, for a starting point (and allowing later change in the light of experience) what amount of stretch (+ or -) do you think is a reasonable allowance? 10%? 25%?

For reference, the stretched diamond I posted earlier has been stretched 30% along the line of flight. I'd consider that not acceptable.

Reminding you of your own post, I agree with your then opinion that all homogeneous distortion is acceptable. I would not put a maximum on it either.
Yes, that means distances between flyers can be ridiculously great. That's much, much less of a problem than Yuri scatter, and the real world will find a reasonable optimum anyway, because you can't fly a grid spanning a state.
Yes, it means you can brief a wide diamond and fly a tall one. I don't see that as a problem, the symmetry of the formation doesn't change.
Johan.
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Picture 3. UNIFORM distortion, skewed (the diagonals of the diamond are no longer at 90 degrees to each other). All the cells are the same shape and size, but no longer square.

Even though this affects the dimensional symmetry of the resulting formation, in my opinion this can be allowed as well.

A Grid System can have its grid adjusted to fit over this, I think, but for a Polka Dot System you would need to consider lines pointing left apart from lines pointing right. Then it would again work, I think.
Johan.
I am. I think.

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Pretty cool.
I think in general, the stretch is the only thing which can occur, even with perfect sightlines. Allowing a minimal scaling of the grid sideways (in/out) to conform the formation (within a certain limit, of a few %) seems reasonable. As it means you can have perfect spacing, flying and distances between each jumper, a formation that's as pretty as you'll ever see, yet a formation that's not 100% confirming to the planned dive.

So, for a starting point (and allowing later change in the light of experience) what amount of stretch (+ or -) do you think is a reasonable allowance? 10%? 25%?

For reference, the stretched diamond I posted earlier has been stretched 30% along the line of flight. I'd consider that not acceptable.

Reminding you of your own post, I agree with your then opinion that all homogeneous distortion is acceptable. I would not put a maximum on it either.
Yes, that means distances between flyers can be ridiculously great. That's much, much less of a problem than Yuri scatter, and the real world will find a reasonable optimum anyway, because you can't fly a grid spanning a state.
Yes, it means you can brief a wide diamond and fly a tall one. I don't see that as a problem, the symmetry of the formation doesn't change.



Yes, that IS what I thought THEN. (Re-reading that thread is interesting).

Having been in two largish formations that didn't skew or curl significantly, and seen pictures of a number of others that didn't, I don't think NOW that we need be tolerant of skewing or curling, we've shown we can build formations that don't.

I also think NOW there SHOULD be a limit to the amount of stretch allowed. I attach a "square" diamond with 10% stretch along line of flight. I think we CAN do as well or better than this. The Illinois 25-way was stretched less than 2%.
...

The only sure way to survive a canopy collision is not to have one.

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I also think NOW there SHOULD be a limit to the amount of stretch allowed. I attach a "square" diamond with 10% stretch along line of flight. I think we CAN do as well or better than this. The Illinois 25-way was stretched less than 2%.



I am beginning to agree more and more with you that the stretch we allow should not be too much from the preplanned formation. There should be SOME stretch allowed, just not too much. So maybe a 5% will do? Hard to tell without flying a lot more bigways...

However, it is important to differ from the USPA grid in allowing one to DECLARE the formation to be flown with whatever angle from the line of flight, not just 45 degrees or 90 degrees.

So if we want to fly a thin rhombus, then we can fly a damn thin rhombus. The grid doesn't allow that, and it should, because a thin (or fat) rhombus can be flown just as beautifully and accurately as a square. Just like that Guinness-rated plane formation record posted about a week ago.

Whatever angle we plan on the ground, whatever angle we dirtdive, that's what is taken into account. By dirt diving over and over again we should be able to find visual cues on our neighbors' rigs (or, like you did on the 68way, put little markers on the helmet visor) to help eyeball the angles accurately enough that the formation doesn't get stretched too far. There may still be a little bit of stretch. But anything too big ultimately shows lack of skill. Like when we started flying and we were doing head to foot formations and there would be a lot of breathing space at the back... the biggest reason being just that all of us noobs were at the back.

This discussion also keeps reminding me of the Texas State Record where I think it was Matt who pointed out that not only were they flying a squished formation, they felt like they had also been dirt diving it that way. In such a case, changing from predeclaring it as a square to predeclaring it as a longer rhombus and redoing the whole jump the same way would validate a record.

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Yea, agreed.
The polka-dot-grid also allows for other formations than grid-spaced ones. And also beginning to think more and more, deviations in angle shouldnt be allowed. Its needed because the flying is like that now, but its not a bad think to set a standard higher than the current one, in terms of whats allowed and what not.
JC
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I think a square diamond and a thin rhombus are equally pretty, and in terms of a formation equal enough not to matter.

It's not that I want looser criteria, but both will make a random onlooker go "oooooooooh pretty," and that is what I would want to achieve. Not "ooooooh within 2% of the dive plan." You want to make it objective, binary, pass or fail, but if you can have rules that encourage flying pretty formations instead of rules that demand major flying skill, I know what I would prefer.

I seem to remember people wanting rules for judging pretty formations as valid and ugly formations as invalid. Where did that change into rules to needlessly require as much skill as possible? I simply don't see that as the intention of having judging rules.
Johan.
I am. I think.

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It's not that I want looser criteria, but both will make a random onlooker go "oooooooooh pretty," and that is what I would want to achieve. Not "ooooooh within 2% of the dive plan."



but pretty is subjective so we need to accurately quantify pretty to eliminate all the if's

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You want to make it objective, binary, pass or fail, but if you can have rules that encourage flying pretty formations instead of rules that demand major flying skill, I know what I would prefer.



requiring a decent level of skill is not a bad thing. Nobody is asking for the impossible. We're saying hey look at the skill we already seem to have, we should at least keep the same standard...
all bigways in other discipline require a certain degree of skill. you don't go on the world 400 or 500-way after just doinga couple dozen 4-ways at your dropzone. you work hard to qualify. let's not even think of the VRW formations and how much tunnel time those flyers have, and how much more air time on top of that.
Records are not zoo dives. Skill should be required. We shouldn't require the impossible, but some basic skill that seems to already be present in most experienced flyers is only fair.

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Yea, agreed.
The polka-dot-grid also allows for other formations than grid-spaced ones. And also beginning to think more and more, deviations in angle shouldnt be allowed. Its needed because the flying is like that now, but its not a bad think to set a standard higher than the current one, in terms of whats allowed and what not.



So how many more must agree before we can say we have a consensus?
...

The only sure way to survive a canopy collision is not to have one.

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