[Routing] generalized routing format - pre-computation

[Marcus Wolschon]

On Thu, 16 Oct 2008 13:16:58 +0200, Sascha Silbe
<sascha-ml-gis-osm-routing at silbe.org> wrote:
> On Thu, Oct 16, 2008 at 12:39:53PM +0200, Marcus Wolschon wrote:
> 
>> Where do you think the most pre-computing occurs?
> For my last prototype (the current one isn't finished yet), the most 
> expensive precomputation was determining whether each way is inside or 
> outside a built-up area ("Geschlossene Ortschaft" for germans). It even 
> prevented me from using a europe dump: it didn't finish within 10 days; 
> the german one only takes a few hours. There's some room for improvement 
> (as I do it in PostGIS, I have to validate each polygon because a single 
> broken one causes the whole transaction to abort), but I still expect it 
> to be very expensive.
> Building an address hierarchy including house numbers would be quite 
> useful, too (and similarly expensive).

Yes, indeed.

How do you go about defining the polygon ofa build-up area?
I am searching if such a polygon was mapped and if not estimate
a radius from the type of town. This of cause if far from being good.
Do you have a better algorithm to "complete" the incomplete data we get
from the mappers on city-limits?

Do you have the polygons indexed by their bounding-boxes to
limit the number of polygons you have to test?
The test itself is trivial. Just counting the number of intersections
of a ray from your location with the polygon and checking if it is
even=outside or odd=inside.

Marcus