Occassional thoughts about orienteering

Sunday, September 13, 2009

Mapping rules of thumb


When I'm mapping, I have some rules of thumb. One is to be cafeful about mapping any feature where I catch myself thinking, "that's be a great place for a control." I've found that when I see a feature and think of it as a control location, more times than not the feature just shouldn't really be mapped.

When I see a feature and think it'd be a good place to put a control, I try to ask myself, "would I notice the feature if I was running past it in the middle of a leg? Would it be useful for navigating on a leg?" Often the answer is, "not a chance."

When I first did some mapping in Sweden I remember vowing to avoid mapping kolbottnar (i.e. charcoal burning areas). As an orienteer, I almost never noticed kolbottnar. But after a bit more experience in the Swedish forest - both racing and mapping - I started noticing kolbottnar. How strange? I still remember updating an old map and noticing some kolbottnar that the original mapper hadn't drawn. I added them.

I couldn't resist myself today. I was working on a sprint map and saw a little wall next to a building. My first thought was to leave it off the map. I decided to look behind the wall. It turns out that the wall surrounds a small area that a course setter could use as a control feature (it is next to a building so it isn't especially difficult). I worked out a way to draw the feature and, I hope, keep it legible at 1:5000. I probably should have just left the feature off the map.

I wonder what other rules of thumb mappers use.

Back to okansas.blogspot.com.

posted by Michael | 6:36 PM


I am afraid to get started, but here's one that came up this past weekend-
* "Up"features get priority over "down" features.

Another quick one-
* Walk first, map second = less erasing.

* Location must be absolute (as possible), otherwise it looks correct to only one person, at one angle, at one time.

* Representation (selection of features and symbols) is much more relative to surroundings, to the point that INconsistency is sometimes useful for readability. (This might draw more comments.)

Better stop. I meant to do only the first one.

Eric W
Eric, interesting. I especially like the first one. I don't think I've ever thought about that before.

Do not get me started on charcoal platforms, I had my share of finding them. The problem is not that it is not a prominent enough feature, most of controls placed on them look like a bag in the middle of the woods, unless you are looking at it from a very specific angle. Another problem with charcoal platforms is with summer vegetation on the ground, neither control nor platform itself, and this is most important, are visible from any reasonable distance. And this is one point I will keep arguing with EricW, otherwise almost always agree with his mapping wisdom :)
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