This approach produces too much shapes and should be used only for irregular structures.
Please give me time for clear specification of this problem and I think, cmif4 can order the adding of this function for rendering.
building:parts=… means, that it is building=…, which consists of several building:part=…, and we should skip volume rendering for such building=…, because we have several building:part=… for such purposes.
Ignoring building:parts=horizontal is not a good idea. I think, that better idea is deletion of building:parts=horizontal from elements in OSM database, for which using of building:parts=horizontal is incorrect.
This is redundant, though, because you could just look at the building:part=* polygons and their tags to find out whether they are arranged horizontally and/or vertically.
building:parts is basically your own invention and has not been discussed before it was presented in the wiki as if it was an established tag. Unfortunately, I still don’t think it is useful. The name is also very typo-prone.
Let me say in other words. It is your decision, to use some tag for some your purposes or not. But if you see, that someone’s work with incorrectly used tag leads to incorrect result, you can not say “ignore this tag”, you should say “delete incorrectly used tag from database”. In this concrete case we see incorrectly used tag - the reason of incorrect rendering is not in bad tag, but namely in incorrect using of tag.
For example, we have tag natural=water for water areas. It is your decision, to render it in some way or not. But if someone asks “why does this soccer pitch render as blue area in this render?” and you see, that pitch is tagged with natural=water, you can not say to author of render “ignore tag natural=water, because it leads to mistakes”, you should say to author of question “delete incorrectly used tag natural=water from pitch”.
P. S. Not all software can determine buildings, divided to parts, by analyzing building:part= polygons. There is a software, which use tag building:parts for such determining. If tag can help some software in some cases, why should we consider it as a harmful?
A tag shouldn’t be ignored because it is sometimes used incorrectly. You are right about that.
The reason why I suggest to ignore building:parts=* is different, however: Because it is redundant, and burdens mappers with a task that should be done by computers.
There are other reasons to determine the parts belonging to a building. For example, the parts are generally understood to “inherit” attributes such as colour from the building. Furthermore, placing parts without grouping them to a building will also cause problems if you place them on a terrain surface, which would introduce unpredictable vertical shifts. So the tag does not actually free software from that task (and even if it did, I would still consider it questionable to trade mappers’ time for CPU cycles in this manner).
Great.
I would suggest adding of couour tag for every possible elements. Of Course we have it more detailed for the buildings, bot there are another elements like e.g. street lamps etc…
Approximation of circle by use of closed semi-circular polygon from the ground floor shape
Use as “height” for this element calculated radius.
Resulution of segments in ground floor by use of closes multipolxgon shape which is drawn.
In z-direction resolution depend of calculated radius. In this case i would say app. 6x dividing…
Thank you for the help proposal but we’re already updating potsgis to get the StraightSkeleton computation done on server side, then i will be in charge of the roof refactoring on client side.
I hope we won’t spent too much time on this improvement
Well,
this is the 3D community discussion portal.
And, this is doocracy. The people do, what works. And this idea is obviously and comes by the way not from me.
The users from the polish community and some italian friends suggests me such solution.