[geos-devel] GEOS and Mapserver

[Ferdinando Villa]

If I can chime in with an almost unrelated one...

what about adding a WKT layer type to mapserver  - should be simple if
GEOS is being worked in. Unless things have changed recently, the only
way to specify a shape was by means of explicit points or polygons. The
WKT layer would make specifying a generic shape a lot easier -
particularly if a program writes the mapfile, as mine do all the time
(and you should see the 150+ LAYER sections for the USA polygon... :)

cheers,
ferdinando

On Thu, 2004-10-07 at 14:27, Steve Lime wrote:
> I've got a skeletal setup in MapServer now. Nothing functional just a
> setup of how this will work. Basically I propose extending the standard
> shapeObj to contain a GEOS geometry. Then I have to write the code to go
> between GEOS geometries and shapeObj's. The wrappers for the GEOS
> functionality then become really easy. You'll see things like
> msGEOSBufferShape and so on. You'll never see the GEOS geometry and will
> deal with shapeObj's. That way you can draw or use those features easily
> with existing MapServer code. I also plan to make use of the PROCESSING
> block as a mechanism to trigger processing. For example you might do
> something like:
> 
> PROCESSING
>   BUFFER 500
> END
> 
> Which would trigger all features to be buffered before being released
> to MapServer or MapScript. MapScript would then gain a whole bunch of
> geospatial analysis methods attached to shapeObjs. That's what I'm
> planning anyways. Now just to find the time to write the converters. WKT
> will likely be too slow for this purpose.
> 
> Steve
> 
> Stephen Lime
> Data & Applications Manager
> 
> Minnesota DNR
> 500 Lafayette Road
> St. Paul, MN 55155
> 651-297-2937
> 
> >>> Godwinl at AGR.GC.CA 10/7/2004 12:29:04 PM >>>
> I've cross-posted this to various lists, so I'm sorry to those who are
> getting duplicates.
>  
> I'd like to beef up my Mapserver applications with some geoprocessing
> functionality - buffers at present, other functions will follow.  For
> now I am playing with PostGIS and having great sucess, IF my features
> are all stored in the database.
>  
> What I'd like to be able to do though, is take a feature from WMS
> getFeatureInfo or WFS and be able to buffer that.  As a test of this,
> I
> took the GML from a getFeatureInfo request and parsed it manually to
> be
> a WKT string.  Then used PostGIS to run the buffer.  Apart from slight
> precision differences, it appeared to be close to what PostGIS would
> have done with it's own feature (the WMS request was done against the
> same feature through MapServer).  
>  
> Now that I confirmed this is all possible, what I am missing is that
> I'd
> like to be able to 
> a.. do the conversion from GML to WKT with some script/library
> b.. do this with a GML stream
> c.. ultimately do this without PostGIS database dependancy.
>  
> I figure that GEOS can do the geometry format conversions, is this
> right?
> Has anyone written a library for linux/windows that will let me talk
> to
> it with PHP?
>  
> I'm prodding these lists in hopes of finding out what else is going on
> out there in this area. It would be fabulous if this was all built
> into
> Mapserver, but from what I can tell, it's just a thought right now. 
>  
> Thanks!!
>  
> Liz Godwin
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-- 
Ferdinando Villa, Ph.D., Associate Research Professor, Ecoinformatics
Gund Institute for Ecological Economics and Dept of Botany, Univ. of Vermont
http://ecoinformatics.uvm.edu