[mapserver-users] CGI mapserv.exe - BUFFER

[Donald Kerr]

I've just had a thought on this one! I wonder if the BUFFER is actually a
buffer to both sides of the XY specified in "MAPXY". That would account for
the resultant image looking approximately twice the distance across that I'm
looking for e.g. a BUFFER of 2000 would result in an image that's actually
4000m (4km) across. I'll have to go back do a bit of experimenting.

-----Original Message-----
From: mapserver-users-bounces at lists.osgeo.org
[mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Donald Kerr
Sent: 08 January 2009 17:47
To: mapserver-users at lists.osgeo.org
Subject: [mapserver-users] CGI mapserv.exe - BUFFER


I'd appreciate it if someone could give me some clarification please?

I am using the following url to return an image:

http://localhost/cgi-bin/mapserv.exe?map=/ms4w/os.map&mode=map&mapsize=500+4
00&mapxy=258544+665909&layers=all&buffer=2000

The documentation states, "BUFFER [distance] - A distance, in the same
coordinate system as the map file, used in conjunction with MAPXY to create
an new map extent".

The coordinate system is in metres so I would expect that the width of the
image (500px) would be 2000m (2km). That doesn't seem to be the case i.e.
the returned images is, at a guess, double that.

I need clarification on what "buffer" is actually doing. No doubt I'm way
off the mark with the deduction above!

Many thanks.

Regards,

Donald Kerr


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