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

Marc Mongenet marc.mongenet at gmail.com
Tue Jun 28 22:10:10 CEST 2022

Well, when I look at
83 nodes for this landuse=forest is already too much with the quality of
swisstopo SWISSIMAGE. Many nodes cannot be sourced by this orthophoto, and
therefore should not be present in OSM. But I don't see how they can be
removed by a "simplifying algorithm" and I certainly would not encourage
such edits.


Le mar. 28 juin 2022 à 21:49, RB <tanrub at gmail.com> a écrit :

> 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 at gmail.com> a
> écrit :
>> 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?
>> 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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