# Need help on complex building

Hi everyone! While mapping Waterwijk in Ypenburg, The Netherlands. I came across this complex building, with skillions and diagonal skillions. Here I provide you with a little sketch I made of the building. Could somebody help me with the correct parameters for this building?

I can’t seem to figure this one out…

In general its a two storey building with building:levels=2, roof:levels=1, building:height=9 and roof:height=2.
But when it comes to roofing its a building with four parts. I would do it like this:

Part #1 (the skillion to the left):
building:height=9, roof:shape=skillion, roof:height=2 and roof.direction=.

Part #2 (the skillion to the right):
building:height=9, roof:shape=skillion, roof:height=2 and roof.direction=.

Part #3 (the skillion along the street):
building:height=9, roof:shape=skillion, roof:height=2 and roof:direction=.

Part #4 (the skillion on the back):
building:height=9, roof:shape=skillion, roof:height=2 and roof:direction=.

YES, I know, its not the real thing. its an approximation. but I can do no better.

[Edit1] actually its a relation with type=multipolygon. to assign multiple roofs you first must convert it into a relation with type=building and redefine the building outline to exclude the inner courtyard. after adding the building:parts you get https://demo.f4map.com/#lat=52.0367663&lon=4.3681569&zoom=19

[Edit2] corrected two height messurements on inner courtyard which seems to be swapped.

[Edit3] found a slightly better roof approximation, which improves visualisation of the shaddowline.
special bonus: works on neighbor roof variants too. so Waterhoeve buildings have finished now.

It does not need a building relation. But a “type=multipolygon” should remain. You can also do both relations.

It depends on the rendering engine. If building parts are present the engine should hide multipolygon and outline. But some don’t. So z-fighting occurs. irrelevant in 2D. but undesirable in 3D.

It’s possible to convert a relation from type=multipolygon to type=building without loss of information. But you have to be very careful. If the MP has multiple inner and outer sections I won’t do it. Same if MPs are nested.

To preserve the inner section you have to cut the outline somewhere. That’s the hardest thing. Otherwise it’s better to have seperate buildings instead of parts. But having parts requires an outline. Without you get a JOSM “missing outline on building parts” error. And F4map won’t show any parts at all.

Thanks for the feedback! It’s a shame F4 won’t render OSM-4D/Roof table, because that will solve this problem I guess. But still this roof shape is very uncommon.

Shame happens if a commercial company focusses on gimmicks like “real time weather effects and 3D animations” instead of fully support osm buildings. Nevertheless its possible do do some 3D artwork.