<span style="font-family: courier new,monospace;">On 6/9/06, Andy Robinson <<a href="mailto:Andy_J_Robinson@blueyonder.co">Andy_J_Robinson@blueyonder.co</a>.</span><span style="font-family: courier new,monospace;">uk> wrote:
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"><snip></span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> Probably 50% of the ways I have created in residential Sutton Coldfield have</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> been non-linear, in that they contain loops, multiple branches and the like.
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> This is because I define my way as one which represents the contiguous</span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> physical street reference, normally its street name. If the named street</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> forks then so do my ways.</span><br style="font-family: courier new,monospace;"><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">I've been doing very much the same. It works fine for rendering, but not very useful for route planning.
</span><br style="font-family: courier new,monospace;"><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">There is a problem though even with rendering, that if a way has multiple branches and the name is positioned half-way along the path of the way then it may hit a discontinuous point and the name gets split into two fragments.
</span><br style="font-family: courier new,monospace;"><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">This can be solved by making each branch a separate way with just the "main" way having a name (for rendering). But this leaves the problem that the branches are unnamed which could be disconcerting for residents of these branches and for the postman ;-(
</span><br style="font-family: courier new,monospace;"><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">It seems like we need some method of making a collection of ways that are all part of the same "road". This could also deal with routes that are discontinuous because of roundabouts, etc.
</span><br style="font-family: courier new,monospace;"><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">This would result in a schema that is something like:</span><br style="font-family: courier new,monospace;">
<br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> Road</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> |</span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;"> |*</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> Way</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
|</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> |*</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> Node
</span><br style="font-family: courier new,monospace;"><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">Alternat</span><span style="font-family: courier new,monospace;">ively, segments could be extended to have contain an ordered list of nodes so that we have:
</span><br style="font-family: courier new,monospace;"><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> Way</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
|</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> |*</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> Segment
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> |</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> |*</span>
<br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> Node</span><br style="font-family: courier new,monospace;"><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
It's conceivable that the Road/Way/Segment should structure should be a single class with hierarchical structure, but this would make it quite a bit more difficult to process (for the average developer who is trying to actually use the data).
</span><br style="font-family: courier new,monospace;"><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"></span><span style="font-family: courier new,monospace;"> --------------
<br> |* |<br> Road/Way/Segment thingy |</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> |</span> | |
<br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> | --------------</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
| *</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> Node</span><br style="font-family: courier new,monospace;"><br>Rigth now, I'm pretty sure that what we have is not sufficient to describe the data we need to model. I don't know if what I'm suggesting is right yet, but it does try to address some of the issues with the current model.
<br><br>Etienne<br><br><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> </span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> The result is, as Richard rightly pointed out, that what I have been mapping</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> for the physical world does not fit well with the algorithms required for
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> path modelling (ie navigation).</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> </span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> So, IMHO, OSM should record the physical and where this means that the</span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> representation of the physical in OSM does not fit with the ideals of the</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> path models then something needs to be added to the nodes and segments that</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> permits the data to be used for path modelling. That could mean additional
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> ways used for this purpose or additional tagging to segments and nodes for</span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> path analysis use.</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> </span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> Cheers,</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> </span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> Andy</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> </span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> Andy Robinson</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> <a href="mailto:Andy_J_Robinson@blueyonder.co">
Andy_J_Robinson@blueyonder.co</a>.</span><span style="font-family: courier new,monospace;">uk</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> </span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> >-----Original Message-----</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >From: <a href="mailto:talk-bounces@openstreetmap.org">
talk-bounces@openstreetmap.org</a> [mailto:<a href="mailto:talk-">talk-</a></span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> ><a href="mailto:bounces@openstreetmap.org">
bounces@openstreetmap.org</a>] On Behalf Of Etienne</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >Sent: 09 June 2006 11:46</span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> >To: <a href="mailto:sxpert@esitcom.org">sxpert@esitcom.org</a>; <a href="mailto:talk@openstreetmap.org">talk@openstreetmap.org</a></span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> >Subject: Re: [OSM-talk] colour fills in osmarender</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >On 6/9/06, Raphaël Jacquot <<a href="mailto:sxpert@esitcom.org">sxpert@esitcom.org</a>> wrote:</span>
<br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >> Etienne wrote:</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> >></span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >> > Are loops and branches in ways a good thing or a bad thing? I can</span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> >> > imagine that route planning applications might find them problematic,</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> >> ></span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >> > Etienne</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> >></span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >> I believe we shouldn't have loops of any sort.</span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> >> routing algorithms like to have straight simple topologies. loops add a</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> >> huge level of complexity that I don't think is necessary</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> ></span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> >To do this, ways would need to be constrained so that segments can</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> >only be contiguous within a way</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >(segment/@toNode=following-sib</span><span style="font-family: courier new,monospace;">
ling::segment/@fromNode). This would be</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >a good thing IMHO.</span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> ></span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >However, if you don't have ways with loops and branches then you don't
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >really need segments at all.</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> ></span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >Some questions though:</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
> ></span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >How would a roundabout be defined? Is that a way or a point?</span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> ></span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >Some roads, especially residential housing estates, can have roads
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> >that split and merge and branch, but only have one name. How can that</span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> >be achived economically?</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> ></span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> >Etienne</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">> ></span><br style="font-family: courier new,monospace;">
<span style="font-family: courier new,monospace;">> >______________________________</span><span style="font-family: courier new,monospace;">_________________</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
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<span style="font-family: courier new,monospace;">> ______________________________</span><span style="font-family: courier new,monospace;">_________________</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
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