[mapserver-users] Ed's Rules for the Best Raster Performance

[Brent Fraser]

Jeff McKenna wrote:
> my quick comments:
> 
> - adding overviews with GDAL's 'gdaladdo' utility is very important

In some cases.  It depends on your data.  As Ed once posted, it may be a good idea to switch to external overviews and merge some of the files to limit the number of file-opens Mapserver must do when the view is zoomed way out.

> - I find your use of the word "pyramid" confusing (this seems to be a 
> word that Arc* users are familiar with but has no real meaning in the 
> MapServer world...I guess I've been on the "good" side for too long ha)
> 
Not being an Arc* user I can't comment on it's origins.  "Overview" is a good alternative, but it doesn't seem to convey the same "multi-levelness" as pyramids.  For example to be able to display the Global Landsat Mosaic, I created seven levels of a pyramid (each an external overview of the higher-resolution below it).  

Hmmm, may be the plural of overview is pyramid... :)

Hey Steve L., maybe we should have a "PYRAMID" Layer type, to replace a set of scale-sensitive TILEINDEX Layers (this would help my every-layer-is-exposed-in-WMS problem too: http://trac.osgeo.org/mapserver/ticket/300).

Brent