Occassional thoughts about orienteering

Monday, April 20, 2009

Nice middle distance course


Here is the middle distance course I ran on Saturday. I have a system for looking at course setting - a set of questions that I use to "score" a course. Let's see how this course does.

1. How many different types of terrain are on the map and how many does the course include?

I see three types of terrain: the north side of the map with a long but somewhat bland slope; the big, rocky hill in the middle of the map; and the urban area with buildings and roads. The course went through 2 of the 3 terrain types.

2. How many legs are longer than 1 km? How many are longer than 1.5 km?

There aren't any legs over 1.5 or 1.0 km. 8 to 9 is close. It actually felt like a longer leg than it was because it offered a couple of route choice options and involved enough climb to make it feel longer than 1 km.

The leg length question works better for longer courses and doesn't work at all for sprint courses.

3. How many direction changes are there?

I score a direction change when you leave the control at a sharp angle (say 45 degrees or more) from the direction you approached the control. For example, you would approach 11 heading almost due east, then leave 11 heading almost due north. That's a direction change.

By my count, there are 8 direction changes (leaving controls 3, 4, 5, 7, 8, 9, 10, and 11).

4. How many legs are either less than half as long or more than twice as long as the previous leg?

By my count, there are 7 legs with big distance differences compared to the previous leg.

Answering those 4 questions gives me a sense of the course. It gives you a description, a "fingerprint" of the course. In general, higher numbers are better than lower numbers. A course with a lot of variety in terrain types, direction changes, and leg lengths is generally interesting.

Back to okansas.blogspot.com.

posted by Michael | 8:29 PM


Direction changes might work better as a percentage. So---number of direction changes divided by number of controls (x100, of course)? (I thought there might be a n-1 or n+1, but when I drew a course with all direction changes, just n seemed to work.)

One metric I like to use is average leg length. I started looking at this after I ran a course I didn't like. It had average legs of 300 or 350m, but nearly all the same length. I shoot for >500m per leg, but I'm okay with less if I like the control picking sections.

For sprints, I've been thinking about "decisions per 100m" as a metric. I haven't actually counted decisions on a real map, though.

I've been accused of overthinking some things...
M21 also had a good course but it was better than the one you ran as there was more direction change. M21 had a long first leg that had three options that for a large part decided the race. Because the green was pretty easy to get through those that ran straight were (much) faster. On the way to #2 I realized how good the green was and realized my round about leg to one was bad. Whether such a leg us fair can be disputed by I liked it. We got a model map and had our chance to check out the mapping style. So overall, one of the better middle courses I've run in some time.

When I compared the red and blue courses, I like the red more - mainly because I liked the route choice leg to 9 (and blue didn't have a similar leg).

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