[OpenLayers-Users] loading heavy WFS. solutions?

[G. Allegri]

Mmm, as I was expecting it's not a good solution for polygons. The
simplification removes the little ones, and it's ok, but it returns a
lot of holes along the polygon boundaries, as it doesn't preserve a
topological coherence. I hope the next release of PostGIS will
integrate the topology suite (at the moment in beta version).

2008/9/18 G. Allegri <giohappy at gmail.com>:
> I was doing it right now :-)
> I was blocked by a problem while I was creating a view for the
> simplified geometries. The simplify alone works fine, but with the
> create view statement it returns empty... But this is something for
> the PostGIS ML.
>
> Thanks anyway for sharing the URL.
>
> 2008/9/18 percy <bjpd at pdx.edu>:
>> I haven't tried this with WFS, but...
>>
>> I display "simplified" geometry when zoomed out with geologic map polygons.
>>
>> I use the PostGIS simplify(the_geom, $vertex_density) command to generate
>> polygons with only one vertex every 500m, for example, when zoomed out past
>> a certain extent. This is served via Mapserver using minscale/maxscale
>> settings at the layer level.
>>
>> You can create different columns of simplified geometries for use at
>> different scales (thegeom_2M, thegeom_500K, etc) in PostGIS. Or you can
>> process the data and spit out different shapefiles for each scale range.
>>
>> Sometimes I can see some artifacts of the simplification, since topology
>> constraints are not part of the process. It has a little "jagginess" like
>> stained glass, but when you zoom in to see what the artifact is, I have
>> substituted the high-res data and it's no longer there!
>> :-)
>>
>> I'm pretty sure this approach will work for what you want to do. You can see
>> a non-openlayers version of this here: http://ogdc.geos.pdx.edu/
>>
>> Cheers,
>> Percy
>>
>> G. Allegri wrote:
>>>
>>> Hi list,
>>> I need to load a heavy GML (the original shapefile is >12 MB), and I
>>> can't make any simplification, beacuse it's composed by little,
>>> needed, polygons.
>>> Has ever been experimented something to do a sort of "pyramids" with
>>> vectorial features? The only solution I can imagine is to produce
>>> various simplifications, and then call different GMLs on the base of
>>> the zoom factor... Well, it isn't a solution, it would be just a
>>> horrible workaround!
>>>
>>> Any idea to share?
>>> _______________________________________________
>>> Users mailing list
>>> Users at openlayers.org
>>> http://openlayers.org/mailman/listinfo/users
>>>
>>
>> --
>> David Percy
>> Geospatial Data Manager
>> Geology Department
>> Portland State University
>> http://gisgeek.pdx.edu
>> 503-725-3373
>>
>