On Wed, 08 Apr 2009 21:24:32 +0200, "Hermann Kraus" <[email protected]> wrote: > What do you think about this idea: Instead of > attaching tags to a way I could find all nodes which are shared by more > than one way and then for each part of a way between two intersection > create a relation like this: > type=metainfo > alt_difference=10.6 > alt_total=27.3 > distance=1032 > with the way and the two intersection nodes as members. > The distance is easily computed while doing the other processing. So the
> routing application could skip this step. Any here are my 2euro-cent.... Sounds like a way to go. With the relations it would be possible to publish only these new relations (so anybody can merge them with the corresponding planet-extract while also merging other data.) as no existing entities are modified. I suggest changing the name to make it clear what point alt_total refers to and if distance is the 2d or 3d distance in meters. Also note that not all nodes with a degree >2 are intersections of 2 roads. It may be something else intersecting (e.g. a node with the sign of a city may be shared by a road and a polygon surrounding the city or it may be 2 power-lines intersecting). >> If I am right then rather then your proposal will need closer >> integration with the routing programme - I think the router will >> pre-process >> the OSM file to calculate distance between junctions - we will want it to >> include altitudes at the same time. > > I explicitly tried to avoid a strong integration with the routers, because > we have more than one and I expect even more in the future. Creating a > library might be an option, if you think my idea is not really good the > other way. I would be willing to add support for your 3d-distance to the metrics for ShortestWay and StaticFastestWay and for the 3d-distance and and alt_difference to my incomplete metric that involves real physics (car accelerating, maximum speeds in sharp curves, ...). However for applications like this later metric alt_difference may be misleading as there may be 2 inclines and 1 decline between the 2 intersections. > However I still would prefer the preprocessor option since this allows to > publish planet dumps which have the altitude information. When the > processing is done by the router one has to publish data for each router > seperatly or the user has to download the SRTM data. I want to make this > application as userfriendly as possible and what could be more > userfriendly than having a world file (or excerpt of it) which already > includes the altitude data. I agree. a preprocessed dump is good for everyone. >> I think your proposal to add a relation is an interesting one - it is >> essentially doing the same thing as the routing program will need to do >> for >> distances - you can imagine doing the same to calculate distance between >> junctions too, which is what the routing programs will do. I am still a >> little unsure how much benefit is gained by your proposed way of doing >> it, >> rather than directly incorporating it into a routing program - the >> routing >> program(s) will need to be modified to read your new relations anyway >> won't >> they? They need support to read the OpenStreetMap anyway and that dump would be in that format. I guess every other format would make it even more difficult and directly building it into a program would bind it tightly to the internal data-structures that one application uses. (They differ widely.) Marcus _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
