Donut Symbol.

[Frank Warmerdam]

On 8/26/05, Bill Binko <bill at binko.net> wrote:
> Another approach is to handle this on the data side: either in Mapscript
> or in the database if your data is in PostGIS (and perhaps through OGR:
> Frank?)
> 
> What I do for this is simply have the data set return a buffer() around
> the point and then display the layer as a POLYGON rather than a point.
> 
> So, if your original data was in PostGIS and your DATA line was:
> 
> DATA "myPoint from (SELECT oid, myPoint from myTable WHERE someField =
>       'someValue') as foo using unique oid using SRID=1234"
> 
> You could just change that to:
> 
> DATA "myPoint from (SELECT oid, buffer(myPoint, myRingsize) from myTable
>       WHERE someField = 'someValue') as foo using unique oid using SRID=1234"
> 
> and change your layer from POINT to POLYGON
> 
> I don't know if OGR can do buffer(), but certainly you could look into it.

Folks,

I just wanted to mention that OGR SQL does not do geometric
operations like buffer.  It is also very simplistic in the sorts
of SELECT statements it supports, so generally when you want to
do this sort of cool stuff you need a real RDBMS.  Of course, 
OGR does support passing sophisticated SQL through to the
RDBMS when operating against an RDBMS. 

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent