[pgrouting-users] Re: Fwd: NiuRouting, PgRouting for SQLite

[Max Weninger]

Hi again

Of course a "simple" bbox is also not always 
helping much for really long routes especially
if lat/lon differs by a large amount since the
resulting bbox still may contain to much data.

If your memory limitation is really that
hard you can only try to "split" the route into
"managable" pieces by e.g. creating "connection points"
(waypoints) on e.g. country boarders or from city to city.

Of course the "hard part" is to find such points 
A DB based solution is not really build for that kind
of "solution"

Regards

max

On Thu, 23 Feb 2012 11:12:50 +0100
Max Weninger <max.weninger at gmail.com> wrote:

> Hi
> 
> On Thu, 23 Feb 2012 11:26:49 +0200
> Jaak Laineste <jaak at nutiteq.com> wrote:
> 
> > 
> > What is the project you're talking about here?
> 
> That is my "own" home-grown current project
> of creating a car-navigation tool based on
> 
> -OSM 
> -mapnik for map generation
> -SQLite + spataialite for some geom data
> -trsp algorithm from pgrouting
> 
> So my comment about the time needed to build
> the graph is for trsp.
> 
> I have not done memory cosumption measurments
> how much memory a trsp graph needs. In my "environment"
> memory is not really a "hard limit". Time is more important.
> 
> Regards
> 
> max
> 
> > Spatialite Djikstra does not really have any query to fetch the
> > data, where bbox could be applied. My understanding is that: a) in
> > pgRouting with every calculation you query route data, graph is
> > built based on it, and graph calculation is done. To reduce data in
> > query you can use BBOX b) in Spatialite Djikstra you pre-generate
> > graph for a table, so you have it as binary fields in special
> > table. This is done once. From about 300MB of routes I got 20MB of
> > graph data. For query this graph is loaded to RAM for calculations,
> > and if you dont have enough of it then it crashes. Actually graph
> > generation itself is quite fast, maybe it could be done for every
> > query, then BBOX system could be hacked in reduce graph size. 
> > 
> > Anyway still bbox limit trick does not scale, especially for longer
> > diagonal roads like "from Seatlle to Florida".
> > 
> > My question was what is approach of NiuRouting to pregenerate and
> > keep graph data?
> > 
> > Jaak_______________________________________________
> > Pgrouting-users mailing list
> > Pgrouting-users at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/pgrouting-users
>