Chris Despite the well-argued views of a minority, I am persuaded by the equally well-argued views of the (considerable) majority who favour option (b).
That is not to say that there isn't room for using a bit of common sense! I wouldn't divide up Delamere Forest into individual areas bounded by paths etc. - the paths in a sense form part of the forest landuse - but I would probably divide a residential area with, say, a major road going through it and would certainly divide landuse=farm either side of a road, for example, if I knew that it was a different farm on either side. Like everything else in OSM, it all a question of judgement! I asked the original question from a neutral standpoint but - in the light of the responses have now developed a preference for option (b) - with exceptions. Of course, nothing is ever final ... Mike Harris > -----Original Message----- > From: Chris Morley [mailto:c.mor...@gaseq.co.uk] > Sent: 06 October 2009 15:46 > To: talk@openstreetmap.org > Subject: Re: [OSM-talk] Landuse areas etc. abutting highways > > Mike Harris wrote: > > Thanks to those who responded to this thread. Advice > gratefully received. > > > > There seems to be a clear majority preference for option (b) > > - the more detailed approach that avoids superimposing > boundaries of > > areas (and their nodes) on an adjacent way (and its nodes). > > I fully understand the two caveats: > > > > 1. It is only worth being precise if there is precise data > available. > > 2. There are a few exceptions where, for example, the > character of the > > adjacent area has access features more like that of a normal linear > > way > > - the pedestrian area is a good example. > > > > I am persuaded that the advantages of forward compatibility and a > > higher standard of mapping justify my small efforts (where > I have good > > GPS data) > > in separating out superimposed areas/ways and using option (b). > > I am particularly pleased to receive support for splitting > single large > landuse areas (e.g. =residential or =farm) > that cross large numbers of ways. > > Let me encourage you to use option a), based on the reasoning > of Frederik Ramm. > > In detailed mapping, everything is an area way which share > nodes with its adjacent areas. When roads etc. are linear > features, it means they have *indeterminate* width and the > only non-arbitrary representation of this in an editor is for > the width to be zero, with adjacent areas on both sides > sharing the nodes - option a). This makes it consistent with > the detailed modelling approach. I would look at the linear > road etc. as being, not a centre-line, but an indeterminately > wide structure comprising the road surface, sidewalks, verges > etc. up to a boundary (which in the British countryside would > often be a hedge.) By mapping with option a) you are saying > that the golf course, say, comes up to the road's boundary > hedge but that you haven't specified exactly where that is. > If you do know, you are into a detailed mapping approach. If > a linear road is still used then it would now be interpreted > as a centre-line, as is sometimes done with rivers. > > Since I map in the same are as you, I suspect that in most > cases you do not have enough information to use the detailed > mapping approach. > Even with arial photography we have available, poor > resolution and interference from tree cover and shadows often > does not allow the separation between the hedges to be very reliable. > > Editor support for ways sharing nodes is certainly poor, but > as with inadequate renderers, we should improve them rather > than adding artificial data (arbitrarily positioned > structures) into the database. > > Landuse areas which cross a large number of ways are very common. > Surely you don't intend to divide say, Delamere Forest, into > a large number of separated areas separated by the paths and > tracks? When you do need to do it, separating an area into > two at a road is certainly laborious and maybe somebody > should build a JOSM plugin to do it. > > Chris > > > > >> -----Original Message----- > >> From: Martin Koppenhoefer [mailto:dieterdre...@gmail.com] > >> Sent: 05 October 2009 15:52 > >> To: Marc Schütz > >> Cc: talk@openstreetmap.org > >> Subject: Re: [OSM-talk] Landuse areas etc. abutting highways > >> > >> 2009/10/5 "Marc Schütz" <schue...@gmx.net>: > >>>> 2009/10/5 "Marc Schütz" <schue...@gmx.net>: > >>>>>> But a) could be used as acceptable temporary solution until > >>>>>> someone with better information (like having aerial > >> photography) > >>>>>> remaps it as > >>>>>> b) > >>>>> Yes, this is basically what I wanted to say. Leave it to the > >>>>> mappers > >>>> whether they want to use a way or an area for a road. > >>>> > >>>> it will be much harder to add this detail, if all areas > >> are merged though. > >>> Not really. JOSM supports disconnecting ways since a long > >> time now. But anyway: doing things wrong just to make > editing easier > >> is not a good thing. > >> > >> +1. That's why adjacent landuses (see topic) shouldn't be > extented to > >> the center of the road. > >> > >>>>> But with option (b) and a linear way you would have a > >> gap next to > >>>>> the > >>>> road. In the case of landuse, this is not a problem in > >> practice, but > >>>> if there is a place, there you need to insert artificial > ways that > >>>> are not there in reality, just to get the connectivity > >> between the two objects: > >>>>> http://osm.org/go/0JUKytHID-- > >>>> which objects are you referring to? parkings usually have > >> those ways > >>>> (for crossing the sidewalk) so they won't be artificial, and > >>>> pedestrian areas are the exception I mentioned above. > >>> Look at the google sat image: > >>> > >> > http://maps.google.com/maps?f=q&source=s_q&hl=de&geocode=&q=bayreuth&; > >> s > >> > ll=37.0625,-95.677068&sspn=59.856937,107.138672&ie=UTF8&hq=&hnear=Bay > >> r > >> > euth,+Bayern,+Deutschland&ll=49.946316,11.577148&spn=0.000754,0.00163 > >> 5 > >>> &t=k&z=20 > >> That's the mentioned pedestrian area. I agree with you here. > >> > >>> Mapping it the way it is done there does not really make > >> sense: Either the exact geometry is important for you, then you > >> should convert both the plaza and the road to areas. Or it > isn't, but > >> then there shouldn't be a problem with extending the plaza > so that it > >> borders to the road. > >> > >> +1. but that's still pedestrian areas / highway areas. In > these cases > >> the areas _do_ connect to the road. > >> > >> cheers, > >> Martin > >> > >> > >> > > > > > > _______________________________________________ > > talk mailing list > > talk@openstreetmap.org > > http://lists.openstreetmap.org/listinfo/talk > > > > > > > ---------------------------------------------------------------------- > > -- > > > > > > No virus found in this incoming message. > > Checked by AVG - www.avg.com > > Version: 8.5.420 / Virus Database: 270.14.4/2416 - Release Date: > > 10/05/09 18:23:00 > > > > > > _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
