<div dir="ltr"><div>I'm surprised to learn that a major developer has reservations and concerns about OSM relations. I don't like them much either. Small ones like simple riverbanks and lakes containing islands are okay but when they get large, they're difficult to understand and nearly impossible to debug. There are myriad tools to "assist" the debugging process but which tool is best to use and when? And how does the tool itself work? I've got a "polygon is not closed" error that I must've inadvertently
caused
on a big riverbank relation in Alaska. When I go into the relation editor and ask it to "jump to the error", it highlights an entire, many miles long riverbank. This is not helpful at all. For the moment I'm stuck. I have much I want to accomplish in my Mapping Alaska (as I call it) project. Debugging an obscure error in a large relation slows me down horribly.<br></div><div><br></div><div>I'll be following this thread to see if I can learn more about how to deal with them.</div><div><br></div><div>Dave<br></div><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr">On Sun, Sep 30, 2018 at 10:28 AM Joseph Eisenberg <<a href="mailto:joseph.eisenberg@gmail.com">joseph.eisenberg@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div dir="auto">Would it be helpful if there were several simpler database primitives for several of the simplest types of relations?</div></div><div dir="auto"><br></div><div dir="auto">I know people have already talked for years about adding a true area object (which now we imitate with closed ways)</div><div dir="auto"><br></div><div dir="auto">Could we also have a linear feature made up of ways only? This would include the current route and waterway relations. Would something like this be helpful, especially if there were a limit to how many ways could be included?</div><div dir="auto"><br></div><div dir="auto">Could multipolygons be specifically defined, perhaps as a type of area?</div><div dir="auto"><br></div><div dir="auto">I do think it is strange that any random collection of nodes and ways can form a relation. And the ability to make relations out of other relations is also confusing.</div><div dir="auto"><br></div><div dir="auto">But it would be quite helpful to be able to make relations from smaller relations, in the simpler cases of a Lake with an island inside (multipolygon in a multipolygon), or a long highway made of shorter routes, or a long river made of shorter waterway relations.</div><div dir="auto"><br></div><div dir="auto">-Joseph</div><div><br><div class="gmail_quote"><div dir="ltr">On Sun, Sep 30, 2018 at 12:01 PM Bryan Housel <<a href="mailto:bhousel@gmail.com" target="_blank">bhousel@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word;line-break:after-white-space"><div><blockquote type="cite"><div>On Sep 29, 2018, at 6:56 PM, Paul Johnson <<a href="mailto:baloo@ursamundi.org" target="_blank">baloo@ursamundi.org</a>> wrote:</div><br class="m_-4495674956839814632m_8673674813274848344Apple-interchange-newline"><div><div dir="ltr">I honestly don't understand why, ten years since it's introduction as OSM's third basic primitive, there's still this weirdly unnatural aversion to relations, even though they're quite a powerful primitive in our toolbox.</div></div></blockquote><br></div><div>From my own perspective as the main developer on the main editor for OSM, the reason I don’t like relations very much is because:</div><div>- every type of node basically works the same.</div><div>- every type of linear way basically works the same.</div><div>- every type of polygonal area basically works the same </div><div><i>- every type of relation is an edge case that requires special code in order not to break. </i></div><div><br></div><div>Relations are also problematic because they are unbounded. Want to make a boundary relation with a million child ways? This is allowed. Want to ensure that all those ways are connected? It may take minutes to download them all. </div><div><br></div><div>They’re almost even a security threat. I’m willing to bet a black hat could design and upload a relation that would destroy OSM.. Or at least, crash every piece of software in the stack that we rely on: mapnik, osmium, and any editor that tries to touch it. </div><div><br></div><div>Anyway, I’m not totally against them, but every one of them is different and I can't spend weeks or months supporting every kind of relation or public transport schema people dream up unless it’s super critical for building a useful map (like turn restrictions). They are really best for features that can not be mapped any other way.</div><div><br></div><div>Thanks, Bryan</div><div><br></div></div>_______________________________________________<br>
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</blockquote></div><br clear="all"><br>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">Dave Swarthout<br>Homer, Alaska<br>Chiang Mai, Thailand<br>Travel Blog at <a href="http://dswarthout.blogspot.com" target="_blank">http://dswarthout.blogspot.com</a></div></div>