Again, in the case of a better source, of course it should be corrected as said earlier ("Regarding the possible imprecision, as Danilo pointed out, the appropriate way to deal with it would be to correct it / shift it, not to damage the data"). I don't think anyone challenges that. It would indeed improve the map and even possibly help document the change of the vegetation over time.

Correcting is an improvement and is a totally different thing when compared to the deliberate data destruction by means of "simplifying" algorithms under subjective preferences of what OSM data should or shouldn't be by self appointed OSM police.  I do personally regularly erase and redraw buildings and landuse when beter sources are available. That unfortunately is not what we are dealing with with the above mentioned data sabotage. 

Le mar. 28 juin 2022 à 21:38, Marc Mongenet <marc.mongenet@gmail.com> a écrit :

Le lun. 27 juin 2022 à 11:38, RB <tanrub@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?

 

Hello,

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:
https://www.google.fr/maps/@46.0985256,7.0849358,3a,75y,103.54h,95.62t/data=!3m6!1e1!3m4!1s3ZO7vmctMaMeZX1HLsG7qQ!2e0!7i13312!8i6656
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.

Marc

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