We have added the overviews and they help but as we are able to fix the zoom levels we are hoping to go a step further.
Thanks Ian -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Frank Warmerdam Sent: Tuesday, December 13, 2011 3:29 PM To: Ian Walberg Cc: [email protected] Subject: Re: [mapserver-users] Raster rendering performance and zoom levels Ian, The normal approach to slow rendering at larger scales is to build pyramids/overviews on large images. This can generally be accomplished something like: gdaladdo big.tif 2 4 8 16 32 64 128 The gdaladdo command should work on virtually all GDAL supported raster formats. There are also things you could do to produce very specific overviews for the particular rendering resolutions you want to produce. But I'd suggest first trying the above generic solution and see if it is sufficient for your needs. Some gdaladdo docs are available at: http://www.gdal.org/gdaladdo.html Best regards, On Tue, Dec 13, 2011 at 3:21 PM, Ian Walberg <[email protected]> wrote: > > > We have an application which is using php mapscript to render maps at > a number of different zoom levels, these zoom levels can be fixed and > the maps are centered on a specific location. > > > > So we calculate the extent based on the zoom level and the current > required center lat/long. > > > > The raster imagery we are using is approx. the same resolution as the > max zoom (smallest extent) and in this case the map rendering is the fastest. > > > > As we zoom out and the extent increases the map rendering is slower, > we are assuming this is because the imagery is being resized which is > processor/memory intensive. > > > > Now the question, how do we create imagery sets for each zoom level > so that they are the required resolution and no re-sizing is required? > > > > We are using mapserver without a client to generate the images on a server. > > > > I hope this makes sense. > > > > Thanks > > > > Ian > > > > > > > _______________________________________________ > mapserver-users mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/mapserver-users > -- ---------------------------------------+-------------------------------- ---------------------------------------+------ I set the clouds in motion - turn up | Frank Warmerdam, [email protected] light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Software Developer _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
