[Mapserver-users] Size of images in ImageCatalog

[Dylan Keon]

Jeff Berry wrote:
> I have DRGs for the State of Washington and I'm struggling with how to tile
> them for display in MapServer.  I've projected and clipped the collars off,
> and am wondering wether I should just keep them at 7.5' quadrangles or clip
> them smaller to say 1.5' blocks.  So, I guess my question is...are smaller
> images necessarily better when in an image catalog for MapServer?  Is it
> faster for MapServer to look at say up to 8 smaller images that are around
> 2-3 Mb each, or is it faster to look at 2-4 larger images that are around
> 7-8 Mb each in to generate the final map?  Maybe there is no significant
> difference.  Hope that makes sense.

I've done the same thing with DRGs for Oregon...created a single 
tileindex layer for the entire state.  I kept the 7.5' quads intact.  I 
can't answer your main question regarding the "sweet spot" for size of 
tiled images, but I can tell you that I've been very impressed with the 
speed of page loads, even when running the app on an older 550MHz PC 
(Linux) with 256MB RAM.

A lot of it also depends upon the scale thresholds you set for that layer...

--Dylan

-- 
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  Dylan Keon
  GIS/Database Specialist
  Northwest Alliance for Computational
  Science and Engineering (NACSE)
  Oregon State University
  Corvallis, OR 97331
  keon at nacse.org        (541) 737-6608
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