[pgrouting-dev] driving_distance Synopsis

[Daniel Kastl]

Hi Steve,

My answer probably isn't complete, but I hope others will add additional
comments.
This is what I think could be improved:

   - Driving Distance should have the possibility to return a polygon, but
   the "core" algorithm should just return a list of points that are within
   driving distance together with useful attributes as for example the cost to
   reach the point, or the previous point ID.

   - Currently it requires CGAL for the "alphashape" function. It would be
   nice, not to have CGAl as a dependency. With PostGIS 2.0 it's maybe
   possible to use ST_ConcaveHull instead.

   http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Alpha_shapes_2/Chapter_main.html

   - For large networks it's a good idea to select only a small part
   (BBOX). This is easy as long as the cost attribute is in the same unit as
   the network data (ie. degree or meter). But if the cost is time for
   example, how to define a BBOX extent? If the BBOX is too small the driving
   distance area will look like the BBOX itself ;-)

Daniel


On Wed, Mar 7, 2012 at 10:36 AM, Steve Horn <steve at stevehorn.cc> wrote:

> Hello list.
>
> I am interested in digging in more to the driving_distance functions to do
> some refining and perhaps improve the usefulness of the results (
> http://lists.osgeo.org/pipermail/pgrouting-dev/2012-February/000458.html).
>
> Having a hard time deciphering the current implementation, mostly because
> of my lack of familiarity with c/c++. Is there someone who wouldn't mind
> giving a synopsis of the overall approach that the algorithm takes?
>
> Thanks!
>
> _______________________________________________
> pgrouting-dev mailing list
> pgrouting-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/pgrouting-dev
>
>


-- 
Georepublic UG & Georepublic Japan
eMail: daniel.kastl at georepublic.de
Web: http://georepublic.de
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/pgrouting-dev/attachments/20120307/1a5a2ee4/attachment.html