<div dir="ltr">Sure! I was just sidestepping about the parking lot example.<div><br></div><div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature">Best, Peter Elderson</div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Op di 14 jul. 2020 om 18:34 schreef Volker Schmidt <<a href="mailto:voschix@gmail.com">voschix@gmail.com</a>>:<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 dir="ltr"><div>Sorry to keep riding this horse, but many of my examples have areas, ways and nodes as members, so they cannot be described by any kind of polygon.</div><div>Lets take my favourite example of a dismantled railway.</div><div>It contains: <br></div><ul><li>nodes: tourist information tables</li><li>ways: embankments, all kinds of highways</li><li>areas: former railway buildings, bridge structures, vegetation areas (that correspond to the former rail bed)</li></ul><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, 14 Jul 2020 at 18:17, Peter Elderson <<a href="mailto:pelderson@gmail.com" target="_blank">pelderson@gmail.com</a>> wrote:<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 dir="ltr"><a href="https://wiki.openstreetmap.org/wiki/Multipolygon_Examples" target="_blank">https://wiki.openstreetmap.org/wiki/Multipolygon_Examples</a> example 1.7 describes disjunct outers. <div><br></div><div>Too bad you have to wrestle through some very complicated examples to get there if you start at the beginning. And, these complex examples should not be followed, because they advocate tying landuse to ways, borders to ways and other stuff you really should not do if you want to keep the map unbroken.</div><div><br clear="all"><div><div dir="ltr">Best, Peter Elderson</div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Op di 14 jul. 2020 om 18:05 schreef Peter Elderson <<a href="mailto:pelderson@gmail.com" target="_blank">pelderson@gmail.com</a>>:<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 dir="ltr">Just two outers is a regular use of multipolygon. <div>If the tags of two areas are the same, you can represent two or more distinct areas as a multipolygon</div><div><br></div><div>If you have one area as a multipolygon with an inner, a separate closed way can be used as an extra outer, it will then get the attributes of the multipolygon.</div><div><br></div><div>Major renderers support this. <br></div><div><br></div><div>One parking lot on two sides of a road is perfect for this method.</div><div><br></div><div><div><div dir="ltr">Best, Peter Elderson</div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Op di 14 jul. 2020 om 16:55 schreef Lionel Giard <<a href="mailto:lionel.giard@gmail.com" target="_blank">lionel.giard@gmail.com</a>>:<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 dir="ltr"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Wouldn't a multipolygon with just two outers solve that parking case?<br clear="all"><div><div dir="ltr">Best Peter Elderson</div></div></blockquote><div><br></div><div>That's a bit of a stretch of the multipolygon definition as there is no inner ring. I never used multipolygon for anything else than complex geometry (with inner ring(s)) and that seems to be what the feature is for.</div><div><br></div><div>As we already have the site relation for grouping features that are part of the same thing, but disjoint, i think that it is good to use it. It also solves the problem when mappers use multipolygon for two polygons sharing the same edge (it is forming an invalid geometry), while with site relation it is not a problem. Another advantage is that it is quite easy to edit. You just need to add or remove a feature : no specific roles (yet) or order needed.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Le lun. 13 juil. 2020 à 23:29, Volker Schmidt <<a href="mailto:voschix@gmail.com" target="_blank">voschix@gmail.com</a>> a écrit :<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 dir="ltr"><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, 13 Jul 2020 at 22:56, Martin Koppenhoefer <<a href="mailto:dieterdreist@gmail.com" target="_blank">dieterdreist@gmail.com</a>> wrote:<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 dir="auto">actually all of these could be „grouped“ with tags alone, e.g distributed museums could have an identifying „network“ tag (or sth similar).</div></blockquote><div>But why invent a new network tag, if we have a site relation, waiting to be used. (I was thinking of open air museums, where the various exhibits are spread over the landscape) <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 dir="auto"><div>For power plants a site might be appropriate, if an area does not do it and you don’t want to rely on only tags.</div></div></blockquote><div>If you have ever looked at the complexities of a hydro-power-plant with dams, lakes, pipes, turbines deep in the mountains or in dedicated buildings . they are really complex, and only parts of it are visible on the surface. <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 dir="auto"><div>In theory objects like the Great Wall in China can and should be modeled as areas, although they seem to be linear in nature, they are also thick enough to „require“ an area representation in order to be well mapped in the scale of OpenStreetMap (you can walk on it). </div></div></blockquote><div>That's not true - you can walk on parts of it, other parts are completely missing, others are heaps of stones. <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 dir="auto"><div>In practice we would also want a way to have preliminary mapping as a line, and mixed geometry relations. A multipolygon relation for all parts of the great wall would likely be broken every day, and would be over the member limits for relations.</div></div></blockquote><div>It's not a multipolygon - it is bits and pieces, some connected, same not. Some may be linear (in first approximation).</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 dir="auto"><div>Would those that are in favour of using a site relation for a linear, circular, interrupted structure, 19km long and some meters wide, also see it as a good relation type for the Chinese Great Wall?</div></div></blockquote><div>You lost me with your question here. <br></div><div><br></div><div>Volker<br></div></div></div><div id="gmail-m_-4227485519747961164gmail-m_-1194931303057811726gmail-m_7578338272934009314gmail-m_-2578868543391359494gmail-m_8037950653339377666DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br>
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