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Technical Topics

Show Profile  mcroxford Posted: 22 June 2015, 10:45 AM  
If there is only one narrow route in and out of a control then it is a dog-leg. Full-stop. Sprint discipline to me is the art of making fast route-choice decisions on the hoof within a technical terrain. It's a mini-long discipline with a range of long and short legs to test an orienteers range of skills at a much faster pace. Fine intricate map-reading can be included but shouldn't just result in a dog-leg. I'd say the issue is the setting not the map or discipline.

Show Profile  Michael Posted: 13 December 2015, 3:37 AM  
There's a final draft of a revision of the international mapping specification ISOM, out for comment. (See mapping thread.) ONZ has referred it to the Mapping Committee, but I think there are some issues that affect how we run the sport of middle to long distance orienteering. The following are not solely "mapping" matters since mappers can do whatever you want in the following areas: declaring a number of features "not to be crossed", the number of greens that we represent runnability with; larger control circles on 1:10,000 maps; and of course the elephant in the room is the widespread use and enjoyment of detailed terrains that cannot be mapped at 1:15,000. They deserve wider debate than just by mappers.

Show Profile  Michael Posted: 22 May 2016, 6:13 AM  
It would be good to hear some opinions about cutting connection lines. (After having difficulty seeing where the next control was, on a sprint map today.) Of course connection lines should be cut where they could hide important map features, but is there any need to cut them when they cross each other? These lines had quite a lot of bends (the course criss-crossed a school) and I think the reason I couldn't find control 11 on the map was that the line from 10 changed direction in a gap where it crossed the line from 2 to 3.

You could also comment on bending connection lines. The downside is that it could "suggest" a certain route choice over the alternatives. But it's often necessary in an intensively used area.

Show Profile  jeffg Posted: 22 May 2016, 3:44 PM  
I was always told to cut connection lines where they crossed another line earlier in the course. It's probably to make sure that the early (earlier) part of the course has the maximum possible clarity, which makes sense. I think bending a connection line is meant to be when there is a compulsory route choice or an area of out-of-bounds to go around, so yes it does imply a route choice when it's used to avoid going through other control circles. A map flip or change is a better idea. Certainly not OK to break a connection line at a bend IMHO.

Show Profile  Michael Posted: 23 May 2016, 2:56 AM  
I've seen a method of avoiding a bend by putting in a semi-circular section on the otherwise-straight line. Kinda like this O----U----O It looks ugly though. A map flip is good (except in MTBO:-)) But my main question is - is there really anything wrong with connection lines crossing each other?

Show Profile  The Map Guy Posted: 23 May 2016, 12:26 PM  
I follow jeffg's philosophy. I have always cut connection lines with the earlier part of the course being the line not cut.

Clarity for the competitor should be the main reason for doing it.

Show Profile  Michael Posted: 25 May 2016, 10:52 AM  
Yes you have been told/always done it. Can we examine whether there is really any impairment of clarity when two lines cross? Esp at nearly right angles?

Show Profile  jeffg Posted: 25 May 2016, 11:18 AM  
Well, I think there are two things, obscuring of map detail where the lines cross and increasing the chance of misreading the lines and switching from one to the other during a leg. Not much chance of the latter if the lines are at right angles, but definitely a greater chance if the lines are more oblique. Cutting the line that occurs later in the course gives more emphasis to the early leg crossing, and gives the competitor a better chance of getting it right earlier in the course when they are less familiar with the map/course. For obscuring map detail, this is more of a case-by-case thing, but I think a line crossing in general obscures more map detail than a single line.

Show Profile  mcroxford Posted: 26 May 2016, 9:27 AM  
Personally I disagree with bending connection lines. I can't think of a reasonable situation that justifies them. If you are planning a course that results in you having an urge to bend a connection line then I would suggest you should seriously consider whether you are setting a fair course for the runner.

But it could be for a perfectly innocent reason. If using Condes, the planner may have settled on a course and inserted gaps on the connection line due to detail or for crossing reasons - but then the planner decides to move one of the controls at either end of the leg. I have noted that Condes seems to bend the line from the gap point rather than realign the whole connection line with the gap still instated.

Show Profile  Michael Posted: 27 May 2016, 3:45 AM  
Agree in general Michael. I've just bent lines in a couple of special cases though. Getting the connecting line on a white course to lie beside the straight handrail rather than on top of it. Around an out of bounds (though I don't know what to do if there's a choice!) And a marked route may not be straight. BTW is there a way of drawing a nice curved marked route? Probably staring me in the face.

Show Profile  Michael Posted: 27 May 2016, 5:17 AM  
Just been looking at the World Cup sprints in Czechia. While the GPS replay might use a special version of the map, the circles and lines are broken so I'm thinking the following observations are valid. No bent lines (bending round OOB is impractical in urban sprints); looks like there was a map change or flip; no breaking connection lines where they cross (breaks are for detail); and the biggest surprise the scale is 1:5000. I thought that was extinct!




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