GEOS integration questions

[Pierre GIRAUD]

On 1/24/06, listuser HH <listuser at herzsys.de> wrote:
> Steve Lime wrote:
>
> >The only GEOS methods exposed are convex hull and a buffer. I didn't
> >want to go nuts until I received some feedback about the usefulness of
> >that type of functionality. They are not difficult to add. Are there specific
> >operators you are interested in and would be willing to test? Let me know
> >if so and we can work in the 4.9 branch.
> >
> >A full list of operators supported by GEOS is available at geos.refractions.net.
> >
> >As for mapfile integration. My idea was to expose a few operators that
> >work of a single shape (e.g. buffer, convex hull, etc...) via the PROCESSING
> >block that is currently used for defining raster operations. That way you
> >could basically apply a GEOS operator to all features of a particular layer as
> >they are read from the data source- for any data source.
> >
> >Steve
> >
> >
> >
> >>>>listuser HH <listuser at HERZSYS.DE> 01/19/06 5:49 AM >>>
> >>>>
> >>>>
> >Hello all,
> >
> >I would like to know how much of the GEOS functions (and which) are
> >already available in the MapScript API and in PHP MapScript. I found
> >only intersects and cointains for both. The shapeObj in PHP Mapscript
> >also has buffer and convexhull.
> >
> >Can someone tell me what the plans for including more of the GEOS
> >functions are?
> >
> >Are there plans to use some functions (i.e. buffer) directly in the mapfile?
> >
> >Are there any docs that give some more information?
> >
> >Regards
> >
> >Norbert
> >
> >
> >
> >
> Hi Steve,
>
> sorry for the late reply I was not in office.
>
> At the moment I'm collecting arguments to convince costumers to use
> MapServer. I know there are many good reasons to use MapServer - mostly
> because of the good work you and the other developers did and do - but I
> want to give a full overview. I tested PostGIS a bit and I think that
> there is much potential but some of our costumers have Oracle and they
> will not use Postgres. So it will be nice to have some of the functions
> available in MapServer.
>
> In the following I have made a list with the things I was thinking of. I
> give a ranking for the importance (1 - most / 5 - fewest).
> - crosses -> 1
> - (boolean) intersect -> 2
> - (geom) intersect -> 2
> - union -> 2
> - difference -> 3
> - getCentroid -> 3
> - getLength -> 4
> - getArea -> 4
> - touches -> 4
> - isValid -> 5
> - disjoint -> 5
>
> If others are interested perhaps we can open a poll for "Geometry
> functions in MapServer" with all the GEOS functions to see what would be
> important for a bigger group of people.
>
> Thanks and my best regards
>
> Norbert
>

For a project, I would need something like collect().

In mapscript, I'm trying to collect (union?) several geometries by
creating a shape and adding all lines that are part of the
corresponding geometries (shapes)
pgiraud but this gives strange results, in some cases (intersects).

Is there any other way to do this, or do I have to wait for the
implementation in mapgeos.cpp ?

Regards

Pierre GIRAUD