[pgrouting-dev] difference between st_convexhull and pgr_pointsAsPolygon

[Stephen Woodbridge]

On 4/15/2015 1:09 AM, Dave Potts wrote:
> On 14/04/15 02:23, Vicky Vergara wrote:
>>
>>
>> > Date: Mon, 13 Apr 2015 20:50:47 +0100
>> > From: dave.potts at pinan.co.uk
>> > To: pgrouting-dev at lists.osgeo.org
>> > Subject: [pgrouting-dev] difference between st_convexhull and
>> pgr_pointsAsPolygon
>> >
>> > Hi list
>> >
>> > I am doing some with the end results of a driving distance calculation,
>> > I can use either st_convexhull or pgr_pointsAsPolygon to turn the end
>> > results in to a polygon
>> >
>> > Q. What is the advantage of using pgr_pointsAsPolygon instead of using
>> > st_convexhull?
>> >
>> > regards
>> >
>> > Dave.
>> > _______________________________________________
>> > pgrouting-dev mailing list
>> > pgrouting-dev at lists.osgeo.org
>> > http://lists.osgeo.org/mailman/listinfo/pgrouting-dev
>>
>> By inspecting pgRouting code, there is some checking taking place...
>> https://github.com/pgRouting/pgrouting/blob/develop/src/driving_distance/sql/routing_dd.sql#L77
>>
>> But now that you are one it, does it give you different results?
> Hi
>
> No Idea, just noted the two different ways of doing and wondered why
> there was an extra method in the pg route package to do something that
> you got by default from postgis.

This is probably because driving distance was written some years ago 
before these functions were available in postgis. My thought has been to 
drop the CGAL dependency and implement the contouring in postgis, but I 
have not gotten around to that yet.

Dropping the CGAL dependency is somewhat less important these days 
because I believe that postgis now has a dependency on that for some 
part of the raster code. It used to be a pain for users build with that, 
but it has gotten better package support now that it is getting used in 
other GIS packages.

-Steve

>>
>> Vicky.
>>
>>
>> _______________________________________________
>> pgrouting-dev mailing list
>> pgrouting-dev at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/pgrouting-dev
>
>
>
> _______________________________________________
> pgrouting-dev mailing list
> pgrouting-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/pgrouting-dev
>


---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com