(The left one, for the case that the focus isn’t perfectly)
Normally it is roof:shape=gabled, but with the shorter part in the north it won’t work. I also tried to work with roof ridge/edge, but i don’t get the right roof.
Basicly I would do a similar approach. Not sure, maybe O2W and Kendzi 3D can figure out the right shape by just using a roof:shape=gabled on the single building outline.
I don’t know how this could work with to parts. I also tried this. The Problem is, that the shorter ridge is not at the highest point. it has no defined height. If I draw a second part there, I don’t know the height and there would be a step.
I think, with the actual Tags it is not possible to tag this roof. If anyone knows, how this could be tagged, please tell me.
It’s a big problem for me, in this area many roofs have this shape.
I don’t known algorithm with could handle this case.
Personally I thing that gabled shape is good approximation of this roof. But if you want to do it more precisely you need to split it into parts, which involve adding heights.
I think, there have to be additional Tags/additional rendering because actually some roofs couldn’t be build in OSM.
If the beginning of a roof is not all around at the same height, you’ll get wrong renderings.
Even the roof I meant in #1 is actually not to draw in OSM.
There have to be solutions for this kind of roofs.
I don’t know how this could work.
Please change rendering rules for roof:shape=round.
If bounding box longer than12 m then resolution= 24 -effective for the half cirlce=12
If the bounding box longer than 20m then resolution= 32 -effective for the half cirlce=16
If the bounding box longer than 32 m then resolution= 48 -effective for the half cirlce=24
We need support of half_dome. I suggest the use of half cirlce in the top view with the attribute roof:shape=half_dome and automatic calculation of the hight from the half circle diameter.
OK. Maybe short description in assembler:
" Cwiartka jablka. Przecinam jablko horyzontalnie, wywalam dolna polowe. Sprytnym ciosem noza po pionie odkrajam jedna czwarta. Dostaje to, jak np wyglada muszla koncertowa filharmonii w operze lesnej przy pomocy tagu depth=value opisujace grubosc konstrukcji robie z tego wneke "
Example: http://images29.fotosik.pl/267/837802be6f3d96f6.jpg
The difference is only - I describe there rectangular shape, but it should work for every possible geometry of building outline.
I think it´s not so complicated to implement it.
If we could keep it simple and use a constant offset to the outline then it should be easy to implement and also work for non-rectangle outlines. What about quadruple_saltbox with only parameter roof:ridge:offset with default offset being roof:height?
In jts/geos this could be implemented with buffer operation and join type mitre. As segments may collapse with this operation (in general) one could get the start of the roof by positive buffering the result by the same amount.
green is the original, blue is flat area and purple is slope area
Edit: of course the offset could also be determined from roof:height together with roof:angle
That buildings are almost square so you should not use roof:orientation tag. That tag it won’t work on square like buildings. You could try to roof:direction but i don’t known if F4 is support it.