Hi Stefano, > I didn't run any specific benchmark on them but my personal experience is on > the contrary a very fast behavior. Indeed I have been using them with > proprietary software, may be the difference is in the ECW sw release used to > access them?
I agree completely that the performance of a single ECW file, is good (I wrote that last mail in a clumsy manner - see what I meant by "big" below). You can "decompress" the single wavelet very quickly as the format is designed with this specifically in mind. > I didn't fully understand how a VRT could help in reducing access time, > letting apart the big problem of format unsupported highlighted by Andrea, > maybe I am wrong but I thought that when using VRT you always have to search > for inner overviews browsing the ECW file. Or maybe you meant creating > external overview in geotiff format? Having a setup where one tiles into a number of ECWs is another thing (here in DK I see a lot of 1km tiles with 10cm/pixel resolution, which are each still reasonably big files). In outer zooms you have to "decompress" many wavelets, and the wavelet idea is kind of spoiled when you break it up into tiles. Instead using a VRT with (external) overviews will reduce your reading to a single TIFFJPEG overview, which performs very nicely. In a couple of setups, I have seen a speed improvement using a pyramid of simple TIFFJPEG overviews over a single very big ECW (sizes of around 10GB), it might be an OS-issue there though (both were on Win as far as I remember). Cheers, Greg -- Hans Gregers Petersen Partner, Senior Consultant www.septima.dk ------------------------------------------------------------------------------ Subversion Kills Productivity. Get off Subversion & Make the Move to Perforce. With Perforce, you get hassle-free workflows. Merge that actually works. Faster operations. Version large binaries. Built-in WAN optimization and the freedom to use Git, Perforce or both. Make the move to Perforce. http://pubads.g.doubleclick.net/gampad/clk?id=122218951&iu=/4140/ostg.clktrk _______________________________________________ Geoserver-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geoserver-users
