[mapserver-users] Mr Sid vs ECW
andy at squeakycode.net
Tue Jul 6 15:55:42 EDT 2010
On 7/6/2010 11:10 AM, Mark Volz wrote:
> Which format is faster ECW or Mr Sid for a large image? P.S. I don’t
> think I will be able to use a tile cache for the application I am
> Mark Volz
> GIS Specialist
Go with ECW. If you have huge CPU power you may not notice, but I run
my maps on AMD64 X2 3800+. Most of the time the cpu sits around 5-10%,
but MrSID uses huge amounts of cpu to uncompress. Its noticeably slower.
ECW will be a little bit bigger on disk, but does not use much at all
for CPU to uncompress.
MrSID is even worse when you have a frontend (like OpenLayers) request
tiles... it'll request two or three smaller tiles at a time. My dual
core was just pegged with requests. Switching to ECW is smooth,
regardless whether your frontend requests one big image or many small.
I can recommend Global Mapper as an image converter. I had several
gigabytes of MrSid split into thousands of files, and GM converted it
into one single ECW, several gigabyes in size.
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