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Discussion: Knoll

in: Spike; Spike > 2016-09-19

Sep 29, 2016 8:45 PM # 
I guess I may have expected more of a knoll there too, but since the boulder was obvious and my bearing was correct I just didnĀ“t think too much about it and continued straight into the control.
My problem was the control before that were I may have lost close to 5 mins mostly caused by misjudging the distance.
Sep 29, 2016 10:37 PM # 
I guess I missed a memo somewhere along the way (not surprising). When I learned to map, stacked form lines were an absolute no-no. When did that change?
Sep 30, 2016 12:44 AM # 
@bubo, I should have been able to adjust, but the combination of the rain and having trouble reading the map with wet glasses must have added some stress. I came right to the knoll + boulder but it was so different from what I expected that I immediately assumed I had gone off track. I looked around the map to see if there were any other boulders I might have come to, and didn't find anything. So I bailed out. I'm pretty sure if I could see the map (i.e. not raining) I'd have recognized the stacked formlines and had no trouble.

@ebuckley, it has always been a no-no. But, it has also been regularly ignored. A lot of Swedish mappers are guilty of it. It might be related to having so much lidar data where it is easy to generate 0.5 meter contours and the mapper starts to see every little slope.
Sep 30, 2016 5:04 PM # 
Mapping guidelines aside, with a 5m contour interval there are going to be times when you're going to want/need more than one form line. Taking the bottom contour as the zero level, what do you do when you have a 1m knoll sitting right by a 4m knoll? In many situations the 1m knoll itself will be quite significant and yet the 4m knoll would tower over it. There are different solutions and some of them will involve stacked form lines in order to reflect on the map what the eye is going to see in the terrain. Mapping is part art and part science.
Sep 30, 2016 8:50 PM # 
I get that mapping rules are really guidelines, but my reading of the ISOM spec was that the prohibition on stacked form lines was one that should not be taken lightly. (I haven't read it in a dozen years, so maybe they've toned down the wording).
Sep 30, 2016 11:40 PM # 
I try not to criticize mapping very much. It is hard and it is subjective. That's why I went back out to the forest to see what things looked like. It was a real stretch to use the double formline. The knoll was very low. Leaving the knoll off would have been an improvement.

This discussion thread is closed.