[Qgis-user] Re: QGIS 1.5 Update for ECW/SID support crashes

[Jean-Claude Repetto]

Le 18/10/2010 15:59, MORREALE Jean Roc a écrit :
> Le 18/10/2010 15:53, Jean-Claude Repetto a écrit :
>>
>> Not only disk size is a problem, but also speed, for example when you
>> want to display the maps at very low zoom levels.
>>
>> Jean-Claude
>
> Make tiles out of the file so just the corresponding tiles get loaded.

Maybe tiling is a solution when you want to get only a small part of the 
map at zoom level 1, but if you want to display the map at zoom level 
1/256 you have to read 65536 tiles to display only one tile.
I have compared GeoTiff (tiled) and ECW, and ECW is MUCH faster at low 
zoom levels.

Jean-Claude