Dec 16, 2020, 15:22 by tomasstrau...@gmail.com: > 2020-12-16, tr, 16:01 Mateusz Konieczny rašė: > >> https://wiki.openstreetmap.org/wiki/Tag:landuse%3Dreservoir#water.3Dreservoir >> (just added) >> > > Thank you. Maybe it is better to discuss here before adding to wiki? > > In my experience it results just in not adding anything at all. It is wiki and can be edited by anyone, so if what I added is wrong it can be changed. > > > My arguments on the points you've added: > > 1. Regarding benefit of having a combining level/tag natural=water. > If today you would query all data with natural=water - you will get > not only lakes and reservoirs grouped, but also riverbank polygons > (totally different beast) and micro elements like water=pond. This > could only be partly useful in the largest scale maps and only if you > make very simple maps and for some reason use the same symbolisation > for such different water classes. For example ponds usually have less > complex and less prominent symbolisation because of their size and > importance. Riverbanks would not need polygon labelling, but rather > use river (central) line for label placement. Most of GIS/Cartography > work goes in middle/small scales and it will be impossible to use only > natural=water there, you would have to add "and water not in > ('riverbank', 'pond', ...)". This erodes the benefit of "one tag" and > makes it of the same complexity from coding perspective as original > water scheme. > I agree that it is useful only for primitive rendering of water areas (that possibly filters water areas by area but does not distinguish between lakes and rivers). It may be worth mentioning. But it is also the most typical and common way of rendering things. > 2. Very important disadvantage of water=reservoir from > cartographic/gis perspective: it allows mappers to NOT differentiate > between natural lakes and man made reservoirs. If first point > describes how different classes are USED, this second point is about > how these classes are CAPTURED. > This is a double edged sword, it also means that mapper unsure whatever something is natural or man made (common in case of mapping based on aerial images, sometimes even in case of survey) is unable to mark a water area. And distinguishing natural vs man made is still possible with water tag anyway. I was unsure whatever it should be listed as a benefit or drawback or both sides explained so I ended not mentioning this. (similarly like I have not mentioned that both natural and landuse are quite counterintuitive key names here)
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