Hello all, There's really no "their" where OSM is concerned - the database is made by individual contributors, without centralized oversight, and much of the mapping is by convention. But looking at the OSM wiki gives some fairly strong recommendations: http://wiki.openstreetmap.org/wiki/Key:building - to paraphrase, "in absence of better data, building-as-a-node is better than nothing at all, until it can be mapped as an area from a better source."
As far as "accurate mapping" - that's a problem and a driving force for the whole of OSM: have you seen the map in 2010? There was a very similar situation worldwide, with most buildings existing as rough outlines or not at all; requiring "perfect or nothing" would have resulted in no OSM, period. That said, the quality of mapping does depend on feedback, especially with new mappers: is the project with badly mapped buildings representative of HOT projects? The ones I've seen (and edited) seem to match building shapes and sizes well - e.g. http://tasks.hotosm.org/project/2520 - but that's also an issue of task validation, in addition to mapper training; I do agree that takes some additional human power in return for much better map result. So, I guess that where time is critical (or space, even though XML compresses well and data for mobile apps is compressed even more efficiently), buildings-as-nodes are an acceptable interim solution, but the ideal case is buildings as well-outlined ways (which is what "experienced OSM mappers" do prefer, btw; no retraining needed). Cheers, Jan "Piskvor" Martinec, OSM and HOTOSM mapper Dne 22. 5. 2017 17:54 napsal uživatel "john whelan" <[email protected]>: > But from your computer science background you should realise there are > costs involved. To mark a building as a node is one line in the database. > As a way well there are four nodes for a start each with its lat and long, > then you have the connecting way. Have you saved a bit of .OSM and opened > it in Notepad++? Try it sometime. Open JOSM download a tiny area ie a > building and take a look. Download a node and take another look. > > So we have time costs in mapping, plus internet costs in uploading the > additional information, storage in the main OpenStreetMap database, > additional costs in downloading, more storage required on smartphones in > the field more processing required at all stages. The time costs in mapping > mean given the number of mappers we have few projects will get mapped. We > also have experienced OpenStreetMap mappers mapping who may not follow HOT > guidelines. These will need retraining and how will you reach them? > > In Africa internet transmission costs are much higher than locally in > North America so ideally we want to minimise these. > > Then you get to the added value. > > Take a look at http://tasks.hotosm.org/project/2656#task/102 when I > validated it recently for a highways project it seemed to me that most > buildings=yes were twice or three times the size of the building sometimes > covering more than one building, at least they were mostly square. For HOT > projects this is not untypical but strange shapes tagged building=yes > abound. I've seen tiles when only half the buildings have been mapped but > the tile marked done. > > The true added value is being able to estimate population. How many people > are there that need to be vaccinated. If the buildings are mapped > accurately then you stand a chance. You may have seen some references to > the JOSM building_tool plugin, try it if you haven't. You take the number > of buildings and their combined area and you can make some reasonable > guesses. The area data is so unreliable you might as well have asked for > nodes and to be honest you stand a better chance of them all being mapped. > > I take it you took all these points into consideration before saying that > building=yes nodes should not be used? > > The place to raise the issue is with OpenStreetMap, its their map and > there will be different points of view and it might be worth checking how > many there are in the map already. > > Cheerio John > > On 22 May 2017 at 11:18, Enock Seth Nyamador <[email protected]> wrote: > >> On personal level I feel mapping buildings as nodes is very wrong so I >> avoid it. >> >> But I think tagging nodes as building should be looked at very well. I >> will recommend it is deprecated. >> >> Best, >> >> - Enock >> >> 2017-05-20 11:38 GMT+00:00 Vao Matua <[email protected]>: >> >>> My opinion is that buildings should be mapped as areas. >>> In un-mapped areas it would be best to create landuse=residential areas >>> first rather than quickly tagging buildings with single nodes. When it >>> comes time to trace buildings it is troublesome to convert single nodes to >>> polygons. >>> For existing single node areas they could be cleaned up on an as-needed >>> basis. >>> >>> Emmor >>> (Palolo) >>> >>> On Sat, May 20, 2017 at 2:10 PM, Bjoern Hassler <[email protected]> >>> wrote: >>> >>>> Dear both, dear all, >>>> >>>> If we're agreed that it's better to map buildings as areas - should we >>>> try to re-map node-buildings from previous campaigns as areas? Or shall we >>>> just leave it? >>>> >>>> Many thanks, >>>> Bjoern >>>> >>>> On 19 May 2017 at 17:54, Cascafico Giovanni <[email protected]> >>>> wrote: >>>> >>>>> AFAIK Osmand renders addr: housenumber also for polygons [1]. >>>>> >>>>> Anyway I agree to the general rule that rendering has to adhere to >>>>> mapping (and not VS). >>>>> >>>>> [1] cascafico.altervista.org/public/Screenshot_2017-05-19-18-40-41.png >>>>> >>>>> _______________________________________________ >>>>> HOT mailing list >>>>> [email protected] >>>>> https://lists.openstreetmap.org/listinfo/hot >>>>> >>>>> >>>> >>>> _______________________________________________ >>>> HOT mailing list >>>> [email protected] >>>> https://lists.openstreetmap.org/listinfo/hot >>>> >>>> >>> >>> _______________________________________________ >>> HOT mailing list >>> [email protected] >>> https://lists.openstreetmap.org/listinfo/hot >>> >>> >> >> _______________________________________________ >> HOT mailing list >> [email protected] >> https://lists.openstreetmap.org/listinfo/hot >> >> > > _______________________________________________ > HOT mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/hot > >
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