<div dir="ltr">Thank you for the extensive answer. Here are some comments:<br><br><div><div class="gmail_extra"><br><div class="gmail_quote">2017-03-02 15:24 GMT+01:00 "Christian Müller" <span dir="ltr"><<a href="mailto:cmue81@gmx.de" target="_blank">cmue81@gmx.de</a>></span>:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div style="font-family:verdana;font-size:12px"><div>
<div>I usually go for a mixture of 1.1. and 1.3., i.e.</div>
<div> </div>
<div>- use building:part for the architectural blocks the building is made of,</div>
<div>with building:min_height / building:min_level where appropiate</div>
<div> </div>
<div>- use type=multipolygon building=*, stuff the usual building tags into that,</div>
<div>this will be rendered by non-aware 3d renderers, i.e. serves backward compat</div>
<div>and will be added in role outline to the following</div>
<div> </div>
<div>- use type=building relation to group together outline and parts,</div>
<div>see <a href="http://wiki.openstreetmap.org/wiki/Relation:building" target="_blank">http://wiki.openstreetmap.org/<wbr>wiki/Relation:building</a></div>
<div>(though I've never used ridge or edge roles)</div></div></div></div></blockquote><div><br><br></div><div>do I understand you correctly, we use 1 way (or multipolygon) for every building:part plus 1 multipolygon relation with building=* as a fallback plus 1 type=building relation for every single building? That's a lot of stuff, but it sounds reasonable in order to map everything in an unambiguous way.<br><br></div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div style="font-family:verdana;font-size:12px"><div>
<div> </div>
<div>As for your point 2. - afair simple buildings allows to define</div>
<div>roofs only along with building:part, so there is no extra</div>
<div>mechanism to define roof elements separated from those.</div></div></div></div></blockquote><div><br><br></div><div>yes, my question was refering to the building:levels tag: where to count the levels, as part of the roof or of the "main part" of the building<br><br><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div style="font-family:verdana;font-size:12px"><div>
<div><br></div>
<div>If you have a roof that deviates a lot from the building</div>
<div>parts it covers (or you want to define the roof as a single</div>
<div>object covering a lot of building parts), you can "hack"</div>
<div>around the proposal's limitation by using extra building</div>
<div>parts for the roof elements in question (or single roof)</div>
<div>that lack a building level and only account for the resp.</div>
<div>roof levels.</div></div></div></div></blockquote><div><br><br></div><div>good point<br><br></div><div>Cheers,<br></div><div>Martin<br><br></div><div>btw.: there's only one aspect of the simple building model which I really detest: the way building:levels in defined for buildings that have "missing" levels. IMHO it should express the number of building levels (like it says), not be a partial information where you have to subtract building:min_level to get the actual building levels number. ...and in case there's a "bridge building" like in the example: <a href="https://wiki.openstreetmap.org/wiki/File:Minlevel.svg">https://wiki.openstreetmap.org/wiki/File:Minlevel.svg</a> the suggestion should really be to use "min_height", as it will often not be clear to which building or floor_height building:min_level refers to (the (existing) levels of the object that has this tag, the left or the right building, or a "standard height"?)<br></div></div></div></div></div>