[mkgmap-dev] Commit: r766: Write more of the *.mp-data.From Alexander Atanasov aatanasov at gmail.com on Thu Dec 4 15:31:22 GMT 2008
Hi, On 12/4/08, Robert Vollmert <rvollmert-lists at gmx.net> wrote: > Hi Alex, > > thanks for your help! > > On Dec 4, 2008, at 13:44, Alexander Atanasov wrote: > > On 12/4/08, svn commit <svn at mkgmap.org.uk> wrote: > > > > > what it does. The road class from RouteParams is set in various > > > places, not really sure they should all get the same. (Why is it > > > > > > > They shouldn't be the same. Some ascii art: > > > > ----------------TRUNK ROAD------L---------------- > > -- local neighborhood streets -| > > |--- --- many small streets --- | > > \ > > -------L- OTHER TRUNK ROAD ---------------- > > > > The small streets should be class 0, TRUNKs class1, etc. > > highways class 6. > > > > > > > > > > > From the small streets you have links to L, how to get on the > > > > > > > > > next road class /i'm not sure but highway herarchies sounds like this/ > > > > Right, the streets come different classes. I'm currently writing this > class in three places: > NOD 2: the first byte is class and speed and two unknown bits (once per > road) > Table A: one byte is class and speed and oneway and toll (once per arc) > Arc: the destination class (this must be wrong) > > For the moment, we're not writing any links. I assume well-placed links > would just optimize routing, but it seems to work without. Links are helpful for fastest route, for shortest may be not. Does the routing work in both modes as expected? > > Are links only ever between nodes on the same road, or can they go further? > Say > A--1--B--2--C > where A and B are nodes in a residential area, 1 and 2 are different small > streets, and C is on a trunk road. Can there be a link A->C? Have to verify this but afaik they are on the same road. Pointers to the nodes that connect to higher road class. So if 1 and 2 are different roads, there is a link to B then to C. > > > > > "destination" class in an arc?) > > > > > > > That's for reading. If you are on node class 5 skip nodes with class < 5. > > The graph is searched bidirectional. Start from pos and dest and try > > to go to a bigger road class. At some point they meet each other. > > In other words when you get on the highway stay there, don't route along > > residental streets. > > > > The class of a node is the maximum of the classes of the roads > it lies on? And the destination class of an arc/link is the class > of the destination node? > > That makes a lot of sense, but I remember seeing some maps where this > didn't seem to be the case. There is a class of the road in net, i think the destination class should be derived from that class. You can reach a node via different arcs with different classes. Node's class itself makes sense only when starting to route from that node, iirc it was always 4 in the cgps compiled maps. -- have fun, alex
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