Help on raster optimization

[Ed McNierney]

Benoit -

In addition to moving your definitions to the top of the EPSG file, there's nothing wrong with editing that file and removing the large number of definitions that you don't use.

     - Ed

Ed McNierney
Chief Mapmaker
Demand Media / TopoZone.com
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
Phone: 978-251-4242, Fax: 978-251-1396
ed at topozone.com




-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On Behalf Of Daniel Morissette
Sent: Monday, October 15, 2007 4:52 PM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] Help on raster optimization

Benoit Andrieu wrote:
> 
> First, the epsg file loaded by GDAL is loaded multiple times near the start of
> the process, I think it is loaded each time an epsg code is mentionned in the
> map file.
> As we are serving UTM, their epsg code (32631 for instance) are lying at the end
> of the file, so Mapserver was reading the file looking for those codes.
> I, then, moved those definitions to the beginning of the file, just after the
> latlong definition (epsg 4326).
> I launched the requests, and saw that the amount of datas being read was much
> lower, but the end-to-end was slow again.
> 

There is a ticket about this issue:
   http://trac.osgeo.org/mapserver/ticket/1976

I'll be making some changes in PROJ (hopefully fairly soon) to add 
caching and avoid re-reading the epsg file multiple times in situations 
like this.

In the meantime, one way around is to move the definition to the top of 
the file as you did, or to place native PROJ4 definitions in your 
mapfile instead of using the "init=epsg:...." syntax. Using native PROJ4 
definitions in all layers combined with corresponding "wms_srs" metadata 
inside the layers will produce a fully valid WMS service.

Daniel
-- 
Daniel Morissette
http://www.mapgears.com/