On Tue, Nov 30, 2010 at 7:48 PM, David Murn <[email protected]> wrote: > On Tue, 2010-11-30 at 19:14 -0500, Anthony wrote: > >> >> > That's nonsense. A way does not show a right of passage. A >> >> > particularly tagged way shows a right of passage. And a park is a >> >> > particularly tagged way. >> > >> > No, a park *CAN BE* a particularly tagged way. >> >> Can be? How can you represent a park in OSM without using a way which >> is tagged with leisure=park? > > Okay, a park that you can route through, is a particularly tagged park.
A way which is tagged with leisure=park is a particularly tagged way. > The point still remains that with incomplete tagging, you have to make > assumptions about whether the park is traversable. Correct. The same is true of a way tagged with highway=footway or highway=steps or highway=proposed or highway=motorway, if it doesn't have any access tags, of course. > See above Indeed. >> > Actually, the fact that its not tagged correctly is a big part of the >> > issue. The renderer has to make assumptions if its not tagged. If >> > there was a tagging scheme to indicate that an area was traversable, >> > then routing engines could start to use it, >> >> There is such a tagging scheme. It is described at >> http://wiki.openstreetmap.org/wiki/Access > > There is also a tagging scheme footway=yes or highway=path. Simply > putting an access=yes tag onto an area doesnt give you any more > information about it. Sure it does, it tells you the area is a right of way. > It doesnt tell you if theres a barrier or gate, > it doesnt tell you if theres a big pond or lake smack-bang in the middle > of the park which you have to walk around. Well, no, of course not. Neither does footway=yes, or highway=path, access=yes, tell you if there's a barrier or gate or a big pond or lake in the middle of the footway/path. If someone maps an area, sticks access=yes on it, and doesn't map the gates, the routers can't be expected to work correctly. Whether or not access=permissive (not access=yes) should be the default is something I can't really say, because I haven't taken a sample to see how common it is for parks with fences to mapped as leisure=park and with no mention of the fence. >> > but Id hate for a routing >> > engine to try and take a short cut 'as the crow flies' through an area >> > which hasnt got ways marked to follow. >> >> I'd love it. It's a feature I'm quite looking forward to. > > If you want routers to route through unmapped areas, then you can simply > ignore the directions given and keep following the map, once you emerge > out the other side of the park, the routing can carry-on from wherever > you happen to come out. I don't want them to route through unmapped areas. I want them to route (via foot) through mapped areas tagged with leisure=park. >> One day OSM will be able to route me from Linkwood Avenue to Pine Bay Drive >> through the park >> (http://www.openstreetmap.org/?lat=28.07187&lon=-82.550402&zoom=18&layers=M), >> saving me 50 minutes of walking. > > Imagine if you tried to save 50min by getting routed across Albert > Park[1]. That big thing in the middle of the screen is a lake that > extends almost the entire length of the park, hence you'll notice all > the walking paths have been mapped in, to allow you to be routed through > the park appropriately. You forgot the link, so I'm going to imagine that the lake was mapped. Obviously a lake is by default foot=no. >> what if someone marked a national park as an area, should routers simply >> show a route ATCF or should it only route through a national park area >> if there is a way to follow? >> >> Routers shouldn't route through all areas the same, any more than they >> should route along all non-areas the same. An area tagged with >> leisure=park wouldn't have the same access defaults as an area tagged >> with building=yes. > > Okay, so what areas are routable then? Is leisure=playground passable? Not sure what the default for that should be. Probably foot=permissive. > What about parking areas, Default is probably foot=permissive, vehicle=destination. > golf courses, schools, graveyards, farms? I'd say the default there is access=private. > All > of these places can sometimes be travelled across, but not all. These > places often also have paths to follow, as do most parks, especially > between entrances. You don't seem to be using the term "park" the same way as is intended by leisure=park. leisure=park is meant for open areas. Just because something is called a park doesn't mean it should be tagged with leisure=park. In any case, as you allude to, routing of vehicles through a parking lot generally shouldn't use shortest path. For foot traffic, shortest path is probably a good approximation. Thanks for the discussion. You raise a lot of good points about how much detail will have to go into the routers in order to properly handle this. I have no doubt one day that detail will be added, though. It's just too huge of a potential time saver for it not to be incorporated, and is a place where OSM and its high level of detail might just be able to get a leg up on the competition. _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
