[mapserver-users] Creating an abutter's list (was: Accessing Vertices of a Shape - PHP MapScript)

[Paul Ramsey]

Why not use PostGIS as your data source and simply test on 
Distance(the_geom,my_geom) < 300 ? As the mapserver home page says, 
"mapserver is not a full-featured GIS system, nor does it aspire to be".

Incidentally, when GEOS (geos.refractions.net) is integrated with 
PostGIS (RSN, RSN, RSN) you will be able to do the exact topological 
test for edge adjacency.

P.

Daniel Morissette wrote:
> Ed McNierney wrote:
> 
>>Daniel's proposal is for ADJACENT parcels, which tend to not be what's required in municipal applications.  The typical "abutters list" requires all parcels that have any point within them lying within some distance (say, 300 feet) of any point within the subject parcel.  In densely subdivided areas, this may include parcels that are several parcels away from the subject parcel.
>>
> 
> 
> Agreed that real buffering is the best solution.  Steve's suggestion to
> honor the tolerance with the shape query would work too.
> 
> As an interim solution, you could set the tolerance to 300 feet and then
> do your query using MS_MULTIPLE (in MapScript) and it will return you
> any parcel within 300 feet.  You would still have to walk along the edge
> of the parcel of interest with a fairly small step value (a few feet
> max), and you should calculate a search tolerance (a little over 300
> feet) to match the step value and make sure you catch *any* polygon
> within 300 feet.
> 
> I agree that this would still return an approximation, but you should
> not miss any parcel if your step and search radius are set properly.  In
> the worst cases you may end up with extra parcels that you would have to
> filter out.
> 
> Daniel


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      | Paul Ramsey
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