Re: [Talk-GB] Imaginery footpaths added by user "Gavaasuren"
On 18/08/14 12:15, SK53 wrote: There are plenty of examples of people building routers for people with restricted mobility using OSM data (for instance wheelchair users, blind people etc). Most of us will map steps on footways simply because even one step acts as a barrier to wheelchair users or many older people. In the case that I'm thinking about, the limitation wasn't physical barriers, but a combination of very slow walking and short gaps between vehicles. ___ Talk-GB mailing list Talk-GB@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Imaginery footpaths added by user "Gavaasuren"
Hi David, Most of these problems are issues for a router for interpreting OSM data, rather than specific problems for the data. There are plenty of examples of people building routers for people with restricted mobility using OSM data (for instance wheelchair users, blind people etc). Most of us will map steps on footways simply because even one step acts as a barrier to wheelchair users or many older people. Fortunately barriers for pedestrians are not as common as they used to be. For places as mapped as areas a simple strategy for a routing engine is to find the centroid and build virtual paths to places on the edges. Similarly such areas can be buffered by, say 5 metres, to determine any overlaps with highways mapped as centre-lines. All such things are relatively simple post-processing steps on the data which can be easily carried out in PostGIS and do not need special tagging on OSM. Many of the members of this list routinely use OSM on a daily basis (we 'eat our own dog food') for pedestrian routing. I have used OSM for this purpose for 5 and a half years and have never encountered any problems other than missing data. My main purpose of routing is to have accurate estimates of time to get to place X (usually a bus stop or railway station) so as not to miss a public transport connection. It works very well. Jerry On 18 August 2014 11:40, David Woolley wrote: > On 18/08/14 10:59, SomeoneElse wrote: > >> Whilst the existance of a highway=pedestrian area that isn't connected >> is an indication of something, it's usually just an indication of that >> mapping in a particular area is not complete. >> > > Considering the longer term problems: > > 1) There needs to be better guidance to routing software developers on how > to route when there are parallel features accessible on foot; > > 2) There needs to be a lot more mapping of barriers. > > Ideally, the routing rule for foot needs to be something like that, > subject to access and surface quality considerations, if there is no > barrier between adjacent features, you may cross at any point between > them. In this case, there has probably been pressure to make life easier > for the router. > > I think this also came up recently with regard to central reservations on > non-motorways. > > The other difficult situation we have here is that pedestrian areas are > mapped physically, as the actual area occupied, but most roads are mapped, > abstractly, as an infinitely narrow line on the centre of the carriageway, > so you will get a gap between the two and the router has to use some > heuristics to decide whether that gap is bridgeable on foot. I have seen > cases where the pedestrian area was mapped out to the centre of the road, > but I considered that wrong. (In fact, mapping roads as areas will > generally confuse routing software.) > > Another variation of this routing problem is that of where is it > reasonable to cross a road. Ideally, physical barriers at the centre of > the road should be mapped, and access restrictions put on any reservations > that is not supposed to be used by the public, but the main consideration > tends to be the level and speed of traffic and the visibility of that > traffic, combined with whether or not there is a designated crossing point > near enough to be used. > > There really isn't enough information mapped to make a decision as to > whether it will be safe to cross. Also, a little old lady may not be safe > crossing at an arbitrary point, whereas it will be no problem for a more > able bodied person. Some people may want to avoid pedestrian subways, > particularly after dark. Any mapping of crime levels in them is likely to > be volatile and may even move the crime. > > Particularly for residential roads, you might get into the dangerous area > of mapping actual maximum speeds on rat runs, as, there is a road near me > with a 20mph limit, but, apart from speed bumps it is long and straight, so > vehicles may get up to 40 mph between bumps, with visibility limited by > parked cars. The council policy is to only use passive enforcement. > Mapping that as 40 mph de facto, may encourage people to use it that way, > but saying it is safe for little old ladies to cross at night, based on the > 20 mph limit may also be wrong. > > Maybe there is a need for a verification tool that renders additional > random interconnections and crossing points, so that one can see whether > there is a need to add barriers, and other hints, to prevent such routings. > > > ___ > 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
Re: [Talk-GB] Imaginery footpaths added by user "Gavaasuren"
On 18/08/14 11:41, David Woolley wrote: >Considering the longer term problems: > >1) There needs to be better guidance to routing software >developers on how to route when there are parallel >features accessible on foot; Agreed. The things that give our routing engine problems are: - dual carriageways. We are limited to "official" crossing points. Many dual carriageways don't even have areas between carriageways, just voids. It is then worse, because the crossing point is often the road "cut through", which is usually marked for foot, and actually less safe for the pedestrian than crossing onto the central verge (although I accept that you can do it right next to it). - pedestrian areas. With an infinite number of crossing "routes", we pragmatically route around the edge of it. Not especially helpful or elegant in many cases, but at least we get a route. - footpaths/cycleways separated from the road. I know why these are mapped this way, but from a routing perspective they are hardly helpful (we want people to transfer from the footpath that they have walked on to the bus that is standing on the adjacent, and unconnected, road). > 2) There needs to be a lot more mapping of barriers. Yes, although until there is it makes it difficult to do (1). Some things - waterways - are obvious. Others less so. > Ideally, the routing rule for foot needs to be something like that, > subject to access and surface quality considerations, if there is > no barrier between adjacent features, you may cross at any point > between them. In this case, there has probably been pressure to > make life easier for the router. We do need to define what we mean as "adjacent" though. And that needs to be something that is understood by the wider community, not just us. > I think this also came up recently with regard to central reservations on > non-motorways. That was me. I decided again the suggestion of using this type of imaginary footpath, though, as I felt that there would be too many and, at the end of the day, unhelpful to the majority of routers/renderers Regards, Stuart ___ Talk-GB mailing list Talk-GB@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Imaginery footpaths added by user "Gavaasuren"
On 18/08/14 10:59, SomeoneElse wrote: Whilst the existance of a highway=pedestrian area that isn't connected is an indication of something, it's usually just an indication of that mapping in a particular area is not complete. Considering the longer term problems: 1) There needs to be better guidance to routing software developers on how to route when there are parallel features accessible on foot; 2) There needs to be a lot more mapping of barriers. Ideally, the routing rule for foot needs to be something like that, subject to access and surface quality considerations, if there is no barrier between adjacent features, you may cross at any point between them. In this case, there has probably been pressure to make life easier for the router. I think this also came up recently with regard to central reservations on non-motorways. The other difficult situation we have here is that pedestrian areas are mapped physically, as the actual area occupied, but most roads are mapped, abstractly, as an infinitely narrow line on the centre of the carriageway, so you will get a gap between the two and the router has to use some heuristics to decide whether that gap is bridgeable on foot. I have seen cases where the pedestrian area was mapped out to the centre of the road, but I considered that wrong. (In fact, mapping roads as areas will generally confuse routing software.) Another variation of this routing problem is that of where is it reasonable to cross a road. Ideally, physical barriers at the centre of the road should be mapped, and access restrictions put on any reservations that is not supposed to be used by the public, but the main consideration tends to be the level and speed of traffic and the visibility of that traffic, combined with whether or not there is a designated crossing point near enough to be used. There really isn't enough information mapped to make a decision as to whether it will be safe to cross. Also, a little old lady may not be safe crossing at an arbitrary point, whereas it will be no problem for a more able bodied person. Some people may want to avoid pedestrian subways, particularly after dark. Any mapping of crime levels in them is likely to be volatile and may even move the crime. Particularly for residential roads, you might get into the dangerous area of mapping actual maximum speeds on rat runs, as, there is a road near me with a 20mph limit, but, apart from speed bumps it is long and straight, so vehicles may get up to 40 mph between bumps, with visibility limited by parked cars. The council policy is to only use passive enforcement. Mapping that as 40 mph de facto, may encourage people to use it that way, but saying it is safe for little old ladies to cross at night, based on the 20 mph limit may also be wrong. Maybe there is a need for a verification tool that renders additional random interconnections and crossing points, so that one can see whether there is a need to add barriers, and other hints, to prevent such routings. ___ Talk-GB mailing list Talk-GB@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Imaginery footpaths added by user "Gavaasuren"
I have already notified tye data working group. The user was contacted, his imaginary work was not reverted and he was not blocked, he continues to add complete junk from his armchair. He needs to be stopped. On 18 August 2014 10:59:22 GMT+01:00, SomeoneElse wrote: >Hi, > >User "Gavaasuren" has been adding a series of imaginary footpaths over >the last few weeks, each with the changeset comment "zwischen >Fußgängerzonen und Straßen Fußweg erstellt". What they seem to be >doing >is joining "pedestrian islands" to random nearby roads in order to >resolve "routing errors". > >Whilst the existance of a highway=pedestrian area that isn't connected >is an indication of something, it's usually just an indication of that >mapping in a particular area is not complete. > >For example, this way(1) was added to connect the pedestrian area to a >random road, but in this instance the mapping of the marketplace as a >pedestrian area is an approximation - what there actually are there >lots >of paths between market stalls, and I'm sure at some point in the >future >it'll get mapped properly. Adding this imaginery footpath doesn't fix >the problem - it's mapped just as "wrongly" now as it was before >(arguably more so), but it does hide the problem from QA sites. > >I've messaged this user 6 times over the last month and although >they've >replied communication does not seem to have occurred (they're still >adding imaginery footpaths). I also resurveyed a relatively local >one(2) to show that, following a survey, what actually exists bears >little resemblance to their "fixes". > >I've just messaged them again saying "please stop!". If they continue >I'll mention it to the data working group; in the meantime I'd suggest >that people check their local areas for these edits and (if they're >invalid) revert them, and if possible survey and map the affected areas > >properly. > >Cheers, > >Andy > > > >(1) http://www.openstreetmap.org/way/297892595/history >(2) http://www.openstreetmap.org/#map=19/53.01357/-1.35353 > > >___ >Talk-GB mailing list >Talk-GB@openstreetmap.org >https://lists.openstreetmap.org/listinfo/talk-gb --- cheers, Chris osm user, chillly___ Talk-GB mailing list Talk-GB@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-gb
