wms capabilities and mapfile scale correspondence

[Ed McNierney]

Trond -

Yes, they are, with one important note.  Since MapServer does not know
the pixel resolution of your screen, it cannot know how many pixels are
used to create "one centimeter on screen".  That's what the RESOLUTION
statement in the map file does; the default value is 72 for 72 pixels
per inch (the units are always pixels per inch).  Since you cannot know
the user's screen resolution either, you can either work with this
estimate or choose another guess of your own.  Most users are running
monitors more in the 100 pixels per inch range these days.

     - Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242  

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Trond Michelsen
Sent: Thursday, April 21, 2005 10:39 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] wms capabilities and mapfile scale
correspondence

On Thu, Apr 21, 2005 at 10:32:56AM -0400, Daniel Morissette wrote:
>> The problem is that they display different values... :s In the map 
>> file I have
>>     MINSCALE 45000001
>>     MAXSCALE 999999999999
>> and in the capabilities file this same layer has
>>         <ScaleHint min="22450.6" max="4.98903e+08" /> Any idea why? 
>> Maybe a unit related issue? I have UNITS DD set up in the MAP element

>> of the map file.
> The different values are normal.
> MapServer's scale values are what you are used to seeing on paper maps

> as scale denominator, e.g. 1:50000, etc.

Just one small question about the scale values.

Are they just like a regular map, so that 1:50000 means that one
centimeter on screen equals 50000 cm., or does it mean that 1 pixel
equals 50000 mapunits?

--
Trond Michelsen