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Re: [udig-devel] Re: ImageIO-GDAL integration
WRT quality, there is a nice study at http://cs.joensuu.fi/~villeh/EI5022-79.pdf
Performance-wise, I don't know of any which would even marginally include the relevant variables like disk bandwidth, memory and cache size, number of clients and cpu performance. All I can offer is that if you have fast disks, lots of space and serve dumb raster imagery to large number of concurrent clients, mosaicked TIFF probably performs noticeably better than ECW. But, in such scenario, you would ultimately want to simply serve cached tiled images from cache to client like google does. This is orders of magnitude faster than anything that requires decompression and/or scaling.
OTOH, rendering ECWs on smart clients can be even more performant than above, since you typically have a fast CPU to burn and ECW bandwidth requirements are quite modest.
So, ECW and a client which can perform ECW decompression could be best option on convenience and performance. As long as you can afford ECW license price, of course :) 

Guido Lemoine wrote:
Is there any quantitative data on ECW versus GeoTIFF comparison (speed, quality)? GeoTIFF appears more "open" than ECW, which also has some nasty limitations on maximum size allowed in the "free" codec. I recall that GDAL was implementing 
JPEG2000 compression in the GeoTIFF standard, but may be wrong on that.

GL

Aleksander Bandelj wrote:
My experience is that ECW decoding is much more expensive than TIFF one. So, compactness yes, speed no. Fine for a single client, but not so good for a server ... 

Andrea Aime wrote:


Paul Ramsey ha scritto:
I would very much like to see an ECW driver or (even better) a JP2000 driver from this project, as such a thing would be widely useful for end users. My priority order would be: JP2000, LAN, ECW, AUX. I assume GeoTIFF is already handled by the existing coverage work? If not, it would go first.
Well, I second Daniele's choice since, at least here in Italy, you either support ECW or they'll start laughing at you. Geotiff is so '90s (it has his merits, but 
everybody seems to have gone nuts for ECW's speed and compactness).

Cheers
Andrea
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
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_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel


_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel

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