Mappers Blog: It was not your fault! Blame the map.

A short analysis on the Glarus Schwändi Map, used for the Swiss Middle Championships last weekend. I was the mapper and I ran the H 40 course for testing purposes. What I am doing now is go through the course and check where the mistakes where made and look for possible map related contributions.

The map

So first, here is the competition map. Have a look at it. Which controls might be tricky?
 

 The rates of mistakes

Here is what winsplits says, if we apply the default 20 seconds/20 percent rule.

And btw. he total number of participants is 46.

Control by control 

The first control is a short one and actually pretty easy. I can be spotted from 50m. Still there is a 30% mistake rate (MR) here. Partly it can be explained with the stressed starting situation. But otherwise one has to admit, that the control ring mask the bigger land form. Also there is a missing dash point on the eastern small knoll.

Same excerpt without overprint.

The second control was easy on the leg, but it seems some (20%) had problems to find the right side of the right stone here. Note how the contours interfere with the black objects.

Then a series with easier controls to 4 ....

... 5, 6, 7....

... 8 and 9. The easiest control of the course.

10 also looked easy but it some took it too easy. Might be a consequence of the climb to 8.

In this section the overprint again masks the terrain. Mostly the dell on the way into 11 and along the gully towards 12. At 12 the MR starts to rise again to over 20%. The mapping inside the control circle is not that clear.

And now to the most tricky section. At 13 MR is 30%, 14 tops with 43% and 15 follows with 21%. 13 and 14 are pretty easy legs, if you look on the map excerpt without overprint below...  13: follow the ditch, 14: follow the valley. A smaller mapping issue can also be spotted south-east  of 13 where the contour has a gap crossing the ditch.

After a pretty physical leg to 16 with a low MR 17 and 18 came back with 26% MR both. The cartographic issues here: The small knoll south of 17, suiting as attack-point is very prominent, but was drawn with a form-line due to over-correctness. A possible source of irritation.  Then on running speed it was not possible to see that the 17th was no boulder but a knoll. Small brown surfaces just melt together with black.
The cliff for the 18th control was, as you can see from the excerpt below, added to make a control point by the course setter...  and therefore was the least prominent cliff mapped on this map.

The last control was no problem from this side. But the elder Hubmann lost some precious seconds going straight over the hill from south-west. Also here the over-print mask the contours.

Resolution

1) Check for the effect of the overprint on the terrain representation, not only the control ring but also the connecting line.
2) Check for legibility issues not only for features with the same color but also between features with similar colors (brown-black)