Thxs for all. I will do the last reply of Piero Cavalieri.
Thxs again. On Dec 14, 2007 11:28 AM, Piero Cavalieri <[EMAIL PROTECTED]> wrote: > You could use gdal_translate (http://www.gdal.org/gdal_translate.html) to > decrease rasters resolution, and then gdal_merge ( > http://www.gdal.org/gdal_merge.html) to create mosaic. The process could > be scripted (but in Windows some gdal commands does not accept jolly > characters). > > You iterate this process some times and at every step you create a tile > index. Every tile index is a Mapserver LAYER, and all of the layers belong > to the same GROUP, which will be used as "the" layer in the query to > Mapserver. > > > > Does this help u ? > > Piero > > > ------------------------------ > > *From:* UMN MapServer Users List [mailto:[EMAIL PROTECTED] *On > Behalf Of *Rahkonen Jukka > *Sent:* giovedì 13 dicembre 2007 9.53 > *To:* MAPSERVER-USERS@LISTS.UMN.EDU > *Subject:* Re: [UMN_MAPSERVER-USERS] ECW Pyramid > > > > Hi, > > > > To my understandment and experience it is unnecessary to have anything > like ECW pyramids if you mean by that the same thing as with Geotiffs, for > example. That is, downsampled versions of individual image files. > ECW has a wavelet based internal system for getting the same effect and it > works fine. > > > > Another thing is that if you are looking your site through tile index and > you have zoomed out very far then pyramid layers (or overviews or whatever > they are called) do not help very much. In this case MapServer has to open > a bunch of physical files from the file system, perhaps tens of image files, > and that will ineviatably slow down the response time. What will help in > this case is a separate, radically downsampled image that covers large area > of your imagery. For example, we have often sites which are 50 km by 50 km > in size and they hold 100 aerial images with 0.5 metre pixel size. > Zooming to whole site through tile index means that all the 100 files must > be opened and it is for sure always slow with any file format and whether we > have fine internal pyramids or not. Pyramids do help a bit but the key to > the speed is to avoin opening so many files from disk. What we use to do is > to create a quick look image with something like 10 metre pixel size and use > that until the user has zoomed in so close that the resolution is not good > enough. At that moment only 1-4 original images must be opened through > tileindex and that goes fast. > > > > A simple way to create a quick look image is to define Geotiff > outputformat in the mapfile and ask MapServer to send the image with whole > site extents with some reasonable width and height. > > > > -Jukka Rahkonen- > > > ------------------------------ > > *Lähettäjä:* UMN MapServer Users List [mailto: > [EMAIL PROTECTED] *Puolesta *José Ramón López > *Lähetetty:* 12. joulukuuta 2007 14:09 > *Vastaanottaja:* MAPSERVER-USERS@LISTS.UMN.EDU > *Aihe:* [UMN_MAPSERVER-USERS] ECW Pyramid > > Hi List. > > I have populated a raster layer using a Tileindex made from ECW Files. > This layer is visible 1:1000 scale with MAXSCALE parameter. > As is not possible to create ECW pyramids. Whe have got another raster > layer resampling these ECW files. > We would like to populate a single raster layer that uses one tile index > created from the resampled ECW, visible at 1:10000 scale (and smaller), and > another tileindex from the original ECW files visible at bigger scales. > Is it possible? If not, please tell me how could I do something similar. > > Tnaks. > >
