Josh Doe wrote: > Here's a shot at a few levels, with a slight orientation towards > routing, probably the most common use of road data: > > Level 0: > Road way present and connected to other ways, and tagged at least with > highway=road if classification is unknown > > Level 1: > Name and classification (e.g. highway=secondary) > > Level 2: > Route number, two ways created (if divided), oneway=* > > Level 3: > Access restrictions, max speed (if warranted, type=route+route=road > relation created to tie ways of a numbered/named route together) > > Level 4: > Turn restrictions, intersections in the form of highway=crossing, > highway=traffic_signals, highway=motorway_junction, etc. > > Level 5: > Bridges and tunnels, surface > > Level n? > Junction relations to tie signals/crossings together, turn lanes added, ??? > > I'm sure I've missed some things, and have parts out of order, so > please provide your feedback.
Some physical keys could be added to the list, such as width and lanes. However, I wonder whether a total ordering is the best approach. Look at the physical descriptions from your example (bridges, tunnels, surface). They are quite independent from legal limitations (access, oneway, turn restrictions, ...). As you have already hinted at, what you want to map first really depends on the applications that you have in mind: many renderers, for example, don't use turn restriction data, but do use bridge attributes; for routing the situation is reversed. I could use other examples, but the bridges are what I immediately wondered about when reading your list. When I started OSM mapping, bridges would naturally be among the first things I would map. The bridge/tunnel attributes are also much older historically than turn restrictions, and adding them requires a lot less editing skills than relation handling. May I ask why you want to assign numbers to these "levels" at all, rather than providing a checklist? If it's also intended as a guide for new mappers, then the complexity of the data structures involved should also be considered (i.e. things requiring relations should be closer to the bottom, stuff that just requires adding a tag should be higher up). > I'm guessing this has been discussed in > some form before, but I can't find it. Please point me to such > discussions if you know of them! The Ramm/Topf/Chilton books contain a suggestion of mapping priorities (including not only roads, but other features, too). They also group the features into numbered levels, similar to your approach. -- Tobias Knerr _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
