Hi, On 12/4/08, Robert Vollmert <rvollmert-lists@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@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