[mapserver-users] CGI mapserv.exe - BUFFER

[Bob Basques]

Donald,

Ahh, I misunderstood your original question, I thought you were trying to buufer a feature.  You want to buffer the view with the features edges.

I ran into this same stuff a while back.  I think I eneded up (at the time) building a whole new BBOX value set with a serverside call.  It was a couple of trips to the server to get thing right, because you needed to get the feature BBOX first, then add in a buffer value to retrieve the real (desired) mapsize.

I think there has been some work on this since my trials with it though.  I'll need to deferr this to someone else I'm afraid.

Sorry about that.

bobb




>>> "Donald Kerr" <donald.kerr at dkerr.co.uk> 01/08/09 1:23 PM >>>
Bobb,

I don't quite follow you there to be honest. The BUFFER states that it's "in
the same coordinate system as the map file". How could that be changed to
image pixel values? What I'm try to do effectively is set the width of the
created image to a certain distance e.g. BUFFER=10000 which (hopefully) will
give me an image that's 10km across no matter what pizel size I set in the
querystring.

Regards,

Donald


-----Original Message-----
From: Bob Basques [mailto:Bob.Basques at ci.stpaul.mn.us] 
Sent: 08 January 2009 19:17
To: donald.kerr at dkerr.co.uk; mapserver-users at lists.osgeo.org
Subject: Re: [mapserver-users] CGI mapserv.exe - BUFFER


Donald,

I haven't tried this, but di you try using Image (pixel) values for the
buffer?

bobb



>>> "Donald Kerr" <donald.kerr at dkerr.co.uk> 01/08/09 11:47 AM >>>
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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