Renaud MICHEL wrote: >Le jeudi 29 octobre 2009 à 13:22, Richard Weait a écrit : >>We aren't really discussing the main building in this case are we? >>More like an awning or a car port? How do we generalize this so that >>it applies in a sensible range of use cases? Multi-lane drive-up >>banks and multi-lane gas stations come to mind as well as drive-in >>restaurants. [1] > >And even restaurant over motorways, see this one >http://maps.google.com/?ie=UTF8&ll=50.654555,5.710015&spn=0.004673,0.008873&t=k&z=17 >which doesn't show very well in OSM either >http://osm.org/go/0GAA7tEY1- > >>I suggest that any tagging on the way should be reduced. With the >>exception perhaps of maxheight. Leave layer for when a motorway passes >>over a carport access road. > >Why limit layer usecase to roads? >It seems appropriate for any features laying at different altitude on the >same (horizontal) position. >And the wiki page[1] says that it can be used for area as well, only >landuse-like areas are excluded. > >[1] http://wiki.openstreetmap.org/wiki/Key:layer
Richard and Renaud, In my original case, my example was the cover extending from a building, over a drive-up bank. Conceivably I could map the extention separately from the building, put it at layer=1, and create a building relation of the two. However there are cases where the building, including the part over the road is much more integrated, and can't accurately be broken apart. In a case like this, where the building is based at level 0, as is the road and parking area. I would use the "covered" tag to denote that the service road proceeds under, not over the building. If I set the road at layer=-1, it would falsely indicate that the road is below the surrounding parking and pedestrian areas. If I set the building at layer=1, then the first floor is not at the pedestrian and road access level. Using "covered" I don't have to falsely state that there is a diffence in levels. Yes, layers can certainly be used for many different objects besides highways. In this case, using layers leads to a false or confusing representation of the physical world. In my opinion, using "covered" to indicate that a highway (road, path, waterway, etc.) goes under something but is not in a tunnel would be a viable option, especially when it is not physically accurate to separate the system into layers. -- Randy _______________________________________________ newbies mailing list [email protected] http://lists.openstreetmap.org/listinfo/newbies
