SID vs ECW

[Mark Howard]

Has anyone compared performance between SID and ECW images? I have data
in both formats, but it SEEMS that the ECW works MUCH better with
mapserv. For example, I have two layers with similar data. Both are
served with a tileindex.
 
LAYER1 --    SID
1Meter color ,6x6km /cell,7Mb per image
 
Initial display @1:100k 8-10 seconds
Pan  @1:100k 8-10 seconds
 
Initial display @1:10k 8-10 seconds
Pan  @1:10k 4 seconds
 
------------------------------------------------------------------------
--------------------------------------------
 
LAYER 2 -- ECW
6 inch color ,12x12km /cell,9Mb per image
 
Initial display @1:100k 3-4 seconds
Pan  @1:100k 3-4 seconds
 
Initial display @1:10k 2-3 seconds
Pan  @1:10k 2-3 seconds
 
 
The ECW images render MUCH faster than the SID images. This is pretty
incredible since the ECW images have 36x the resolution (6x X 6x)
 
 
 
 
 
 
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