Ian, I am guessing you actually have many files, not just one big one. Is that right? As you zoom out opening many files to accumulate the full image is expensive. Up to some scale it is practical to merge things into one big mosaic tiff with overviews. At some point that can be impractically large.
The usual practice to avoid opening too many files with tileindexed layers is to have two LAYERs in your map file. One for the fuller resolution data, and then another at greatly reduced resolution and then to generate a reduced resolution mosaic for the reduced resolution layer. Use the MIN/MAX SCALE control keyword in the LAYER to control which is used. Best regards, On Fri, Nov 11, 2011 at 11:15 AM, Ian Walberg <ian.walb...@airborne.aero> wrote: > Does anyone have any experience of how to get the best performance out > of raster formats. > > We have an application which needs to be able to display a number of > zoom levels and once we get out to whole earth or continent level the > performance is poor. Our assumption is that it is the shrinking of the > images which where is the time if being used up. > > The raster files are tifs with external world files, adding overviews > helps a little. > > The zoom levels and output resolution can be fixed so if the overviews > match exactly the required image size that look like it would work but > we cannot see how to do this. > > So any advice on what are the most efficient file formats to open and > the most efficient output format. > > The application is written in php mapscript which runs as a service and > not via a browser. > > Thanks > > Ian > _______________________________________________ > mapserver-users mailing list > mapserver-users@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/mapserver-users > -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmer...@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Software Developer _______________________________________________ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users