OSM's model of creating objects is somewhat different from traditional map making, drafting and cartography (and the data that nowadays creates these). Whereas OSM started by creating feature centrelines and defining a width etc at the render stage most traditional mapping and cartography thinks of edges, the edge or a road (kerb), or edge of a building etc. Now of course OSM has developed over the years such that we now draw quite a lot of edges (coastline and river banks and building outlines being examples foremost in my mind) especially where a centreline just doesn’t cut it but OSM is not really every going to be a good representative model for the very detailed accurate type of edge based maps that the OS supply for engineering and planning purposes (MasterMap). We could add kerb lines and other edge limits to OSM but it's never going to be achievable globally so little benefit in doing it locally unless you have a specific desire and reason to do so.
-----Original Message----- From: David Woolley [mailto:for...@david-woolley.me.uk] Sent: 14 January 2015 08:07 To: talk-gb@openstreetmap.org Subject: Re: [Talk-GB] Fwd: What are you mapping and have you fully though through the implications of bad data ? On 13/01/15 22:23, Pmailkeey . wrote: Making large numbers of points all at once will almost certainly result in people latching onto just a few, even when you spread them over multiple postings. Also, many of these are not UK specific. > It's annoying to add things to the database and find them not > appearing on a general map - is there not an 'all data map' ? > Sidewalks - which The map is the data, not the rendering. You do see a more complete rendering in show map data mode or in an editor, but that, inevitably means you can show less attributes, if you want to keep the clutter down. > I've used to mark kerbs as they should be marked. This leads to why I > left OSM years ago: That sounds more like a plan than a map. Having a reasonably high level of abstraction is actually useful for most of the applications of the map. I don't know how OS handle it, but I assume they have both the abstract mapping details to support 1:10000 and up, and a higher level of detail for the sort of plans used in planning applications, rather than dynamically deriving the abstracted roads from the detailed kerb lines. In fact, when people do micro-map things like footways (still as lines), the transition between those areas and more abstractly mapped areas tends to be awkward, and it tends to imply barriers that don't exist in the real world. We currently have very poor coverage of more useful things, like house numbers, and in many parts of the world, even road names, so the map is not going to grow well if you insist on everyone micro-mapping to this level, so most of the map is always going to abstract sidewalks into the road. It is possible to map roads and pavements as areas, but you loose direction information when you do that. Again, transitions are awkward. Also, the surveying tools available to amateurs make mapping detailed kerb lines almost impossible. At best they will be relative to a carriageway centre which has an uncertainty which is often wider than the road. _______________________________________________ Talk-GB mailing list Talk-GB@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-gb _______________________________________________ Talk-GB mailing list Talk-GB@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-gb
