[Routing] [OSM-dev] pre-compute routing

[Marcus Wolschon]

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Hello Steve,

I'm Marcus, doing the Traveling-Salesman application
(http://sourceforge.net/projects/travelingsales).

You cannot do precomputed routing for 3 simple reasons:

1)
Routes are optimized for a specific metric like "shortest",
"fastest", "fuel-efficient" and every metric can be parametized
like "use less Autobahn", "use no maut-streets", "use no ferries",
... .

2)
There are things like traffic-jams, temporary building-sites, ...
where a road is either blocked or to be avoided.

3)
The map is dynamic. Every time you change a road (every minute)
there are millions of routes that may change or be added.


Marcus


Steve Coast schrieb:
> (please reply to the new routing list, sent to dev so that you know
> it's there)
>
> We have about 4 million ways.
>
> The total disk space to store all routes is therefore
>
> ~= 4 * 10e6 * (L * B) * N
>
> I'm going to go out on a limb here, and almost any route I've got
> directions for is about 10 steps. Some will be more of course, but
> many will be much less.
>
> ~= 4 * 10e6 * (10 * 2) * 3 ~= 240 million bytes.
>
> This, I'm told, is exactly what Google do. But their dataset is a bit
> bigger.

Google is a very bad routing-application.


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