[talk-ch] vandalism under the pretense of "simplifying"

Marc Mongenet marc.mongenet at gmail.com
Tue Jun 28 21:37:53 CEST 2022

Le lun. 27 juin 2022 à 11:38, RB <tanrub at gmail.com> a écrit :

> A user is destroying precise landuse mapping in Wallis. "Simplifying" in
> this case turns precise landuse cover into weird angles and destroys the
> work done by the previous contributors while harming the OSM database. Such
> moves could furthermore clearly be perceived as aggressive.
>  Typical examples of the vandalism can be observed there
> https://www.openstreetmap.org/way/965324922/history#map=19/46.02973/7.11287
> What is the appropriate way to react to such attacks against the project?

I did some mapping in Wallis last week, and obviously noticed the
landuse=forest mapping.
I must first say that I am very impressed with the size of the area mapped
with better than normal accuracy.
But I have to put (very) cold water on this enthusiasm.
The forest mapping in Wallis is not accurate; it is not micro-mapping; it
is a fancy sine wave around the actual (usually straight) land use; over
95% of the nodes are based on shades, non-orthogonal projection of the
canopy on the ground, or pure invention. They are not based on terrain, and
removing most of them actually improves the accuracy of the map.

Here is an example. If we look at this (non-free) data:
a straight line of trees and a straight fence marking the boundary between
the forest and road land use are shown.
The most accurate mapping would have been to use the fence as the boundary
of the landuse=forest, but instead there is a sinusoidal curve that even
has a few nodes on the motorway asphalt. It is very noticeable with the
swisstopo SWISSIMAGE now that most of the trees have been cut down.

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