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Author Topic: "Proximity" definition  (Read 6958 times)

Offline Charles Martèle

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"Proximity" definition
« on: February 07, 2013, 02:01:03 pm »
Hi guys !

As an introduction, I'd like to say that the glossary definition of "proximity" has been quite bothering me  :-\

[rule]Proximity : A measure of distance for in play skaters that is defined as skating not more than 10 feet (3 m) in front of or behind the nearest pack skater.[/rule]

The issue I see here is that the definition for Proximity refers to the word Pack, and the definition of Pack (which I won't write here, but trust me ^^) refers to the word Proximity. Circular dependance error ? Anyway, one can say that's a triviality : i would tend to agree, but still, for me this is not a thorough definition.  >:(

Anyway, the main question I wanna ask here is about 4.1.2.1 :
[rule]4.1.2.1 Distances  for  determining  the  pack  and  the  Engagement  Zone  are  measured  as  the shortest distance  parallel  to  the  track  boundary  between  skaters' hips  (see  Glossary for  “hips”).[/rule]

Noticing that the outside track boundary is not parallel with the inside one (cf. Track Design appendix), one can say that, again, this definition is quite strange.  ::)
Ok, let's assume that we take into account the inside track boundary for such distance measurement and continue.  ;)

I very well understand what 4.1.2.1 means when the skaters are in the straight lines. In picture 1, the "derby distance" between skaters A and B is 6 feet (and not 12 feet) and skaters are therefore in proximity.

When the skaters are in a turn though, I'm not sure how to measure such a distance. In picture 2, what is the "derby distance" between skaters C and D ? I think everybody will agree this is not 10 feet since this measurement is not in any way parallel to any boundary. But is the correct distance :
- 8 feet (parallel to the boundary, going through skater C)
- 11 feet (parallel to the boundary, in the middle of the track, where the 10-foot marks lies)
- 12 feet (parallel to the boundary, going through skater D)
?

Any opinions ? Any "nobody cares about that" ?  :P

Offline Anton Deck

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Re: "Proximity" definition
« Reply #1 on: February 07, 2013, 02:30:25 pm »
It is the distance infront or behind a skater (distance along the track) that defines proximity, for both pack and engagement zone.

On the straights thats quite simple to measure obviously.
Example one the skaters are 6ft apart for the purposes of judging proximity, although the literal distance between them is further.

Example two is more complicated, as you rightly point out the corners require more thinking.
The method that has been taught at WFTDA clinics is known as the box method. See here http://www.zebrahuddle.com/index.php?topic=1442.0 and here https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-snc7/308690_258788907493306_239636724_n.jpg



Offline SeerSin

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Re: "Proximity" definition
« Reply #2 on: February 07, 2013, 03:37:56 pm »
The pack is measured in a forward and backward direction in a straight line. So it's 10 feet in a straight line from hip to hip. I can't make graphics to show you on my crappy work computer so I'll try to describe it.

Imagine on the curve you have a big square that is 10 feet on all sides. Place that square on the track and use it to measure the distance. So in your second scenario the skaters are more than 10 feet apart.

Details: the 10 foot lines on the track can be misleading. On the inside of the curve they're only 7 feet apart while on the outside they're 14 feet apart. For this reason many now lay down only a partial line(about 3 feet long) in the center of the track instead of running the 10 foot line all the way across the track.


Offline Charles Martèle

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Re: "Proximity" definition
« Reply #3 on: February 07, 2013, 04:08:08 pm »
Thanks guys ! That makes sense ; unfortunately, I had never heard of this box method before (looking forward to the Eindhoven Clinic !!).
Anyway, the rules could really be clearer on this point :'(

Offline SeerSin

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Re: "Proximity" definition
« Reply #4 on: February 07, 2013, 04:16:02 pm »
Thanks guys ! That makes sense ; unfortunately, I had never heard of this box method before (looking forward to the Eindhoven Clinic !!).
Anyway, the rules could really be clearer on this point :'(

Well sure, but the rules just lay out what the game is. Then we as officials develop some methods and practices to implement those rules. This is one of those things officials came up with on how to best implement the pack definition rules on the curves.

Offline Brass Monkey

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Re: "Proximity" definition
« Reply #5 on: February 12, 2013, 04:33:37 pm »
I have never heard it referred to as "The Box Method" but that is consistent with how I was taught and how I explain to skaters when they ask questions about it.  Derby would be easier to ref with out curves. 


All in favor of removing curve?


But yes, "box method", new reffing term added to Derby-Ref-edex.
#87 Brass Monkey

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[Former] Skater - Chicago Bruise Brothers

Offline SeerSin

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Re: "Proximity" definition
« Reply #6 on: February 12, 2013, 11:11:50 pm »
I don't think "The Box Method" is in any way part of the derby lexicon so you'll probably get a lot of blank stares when using the term.  ;)

Offline Numb3r Crunch3r

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Re: "Proximity" definition
« Reply #7 on: February 12, 2013, 11:26:22 pm »
I don't think "The Box Method" is in any way part of the derby lexicon so you'll probably get a lot of blank stares when using the term.  ;)

I have even heard 'pack definition' and 'clockwise or counter-clockwise?' on the curves be referred to as 'lasagne sheets and pizza slices'. Whatever works for your brain :P

Offline Megapickle

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Re: "Proximity" definition
« Reply #8 on: February 12, 2013, 11:51:04 pm »
[...] many now lay down only a partial line(about 3 feet long) in the center of the track instead of running the 10 foot line all the way across the track.

<derail>
I tried something new at this weekend's bout: The normal 2-foot-by-2-inch high-contrast lines as ten-foot reference. But I extended them on each end with 3-foot-by-1-inch lower-contrast lines as ccw/cw/perpendicular reference. So each line looked like:
|  _________  |

I loved how well it worked out & I think I'll be doing it the rest of our season.

Offline Major Wood

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Re: "Proximity" definition
« Reply #9 on: February 13, 2013, 12:42:04 pm »
[...] many now lay down only a partial line(about 3 feet long) in the center of the track instead of running the 10 foot line all the way across the track.

<derail>
I tried something new at this weekend's bout: The normal 2-foot-by-2-inch high-contrast lines as ten-foot reference. But I extended them on each end with 3-foot-by-1-inch lower-contrast lines as ccw/cw/perpendicular reference. So each line looked like:
|  _________  |

I loved how well it worked out & I think I'll be doing it the rest of our season.

That's why I like full length 10' lines. Much less for distance than a point of reference for angle.
Your friendly Zebra Huddle admin.

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Offline Celtic Raider

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Re: "Proximity" definition
« Reply #10 on: February 13, 2013, 04:20:31 pm »
Agree MW.  We finally got full 10' lines on our home track (after much complaining from me about the lack of them) and makes pack definition MUCH easier.

Offline Megapickle

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Re: "Proximity" definition
« Reply #11 on: February 13, 2013, 09:18:32 pm »
Agree MW.  We finally got full 10' lines on our home track (after much complaining from me about the lack of them) and makes pack definition MUCH easier.

Wait, huh? Pack definition is precisely what the full lines are not beneficial for, as compared to the center-track short lines (on the curves, that is). Do you enjoy doing calculations in your head such as: "She's 2' from the inside line, so the 10' lines are actually 8' apart here, so is that other player more/less than 2' in front of the next 10' line"? With the short dashes, you have a clear 10' reference nearby, which in your head you 'slide' over to where the skaters are. To each his own, but I find that 2nd mental exercise much easier in the moment.

Offline bmd (2113)

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Re: "Proximity" definition
« Reply #12 on: February 25, 2015, 03:28:21 pm »
I notice that the link to the image was broken. (I was looking for it.) Here it is again.
Alex Cline
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Offline Bitches

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Re: "Proximity" definition
« Reply #13 on: March 04, 2015, 01:35:34 pm »
Those two skaters are in proximity in BOTH images posted by Charles.

The distance is measured along the line parallel to the inside track boundary. As someone else mentioned, in the straightaways that's easy. In the corners, you have to draw the line that is a tangent to that point on the curve.

Basic geometry dictates that if the two skaters' hips are exactly 10' apart (as shown in the second image) unless that line is also parallel to the inside track boundary, they are less than 10' apart according to the rules because that 10' is automatically the hypotenuse of the triangle and the side of the triangle that is parallel to the inside track boundary must be shorter.

I drew in some squares on Charles' example, and the geometry of his triangle showing the line parallel to the inside track boundary must be shorter than 10', and I drew in some boxes.

I also did this video on pack and cover this very same topic a couple minutes in:
http://youtu.be/BWhfMDmXaWg?t=2m13s
(See, especially at 3:40)
« Last Edit: March 04, 2015, 01:44:14 pm by Bitches »
I'm always happy when my skates are on.

 

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