very large tile index

[Stephen Woodbridge]

Christopher Condit wrote:
> I've got a fairly large set of .tif files (A total of 2774 images at
> roughly 400mgs each). They've all had gdaladdo run (at 2 4 8 16), and
> then a tile index created. If I attempt to draw the map with mapserver
> at the full extents, the cgi request times out. I realize this is too
> much data, but the question is: how do I find out at what point the tile
> index will break down and overview should be used? Also, if MapServer
> won't draw the composite image, will shp2image work?
> This is running on a linux machine with 4 2.8 ghz Pentiums and 4gb
> RAM...

At full extents you still have to open 2774 images and depending on the 
zoom scale you might still need to take the 16th over and reprocess that.

What you need to do is create external overviews using gdalwarp and then 
use min/max scale to control when to use the external overviews

-Steve W