Re: [mapserver-users] Raster Strategies Examples
On 08/03/10 16:06, Daniel Morissette wrote: Jan, Jeff, If you have ideas of an easier mechanism to help determine scales that you would like to see added in MapServer then please share them... I'd be happy to help improve this. As a rule of thumb, for raster maps I compute the scale that displays one pixel from the raster file as exactly one screen pixel. The optimal Maxscale-Minscale breakpoints between two raster maps are generally exactly in the middle of those basic scales (depends a bit on format and compression ratio). For vector maps I start with the scale needed to display the whole map on a 1000*1000 screen (becoming the largest Minscale) and try to figure out efficient breakpoints for smaller scales by counting the number of elements in the files. Most of the time, my Maxscale/Minscale pairs for different layers are derived by multiplying/dividing by two, on the basis of those basic values. Those are just rules of thumb of course. I'm not sure whether they could or should be generalized into MapServer directives. Jan ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-users] Raster Strategies Examples
Daniel Morissette wrote: Jan Hartmann wrote: Would it make sense to add this functionality to MapServer? Finding scale breakpoints is a hassle indeed! Jeff McKenna wrote: I've always used a simple CGI template containing the [scaledenom] parameter. I plan to simplify this for MS4W users. Jan, Jeff, If you have ideas of an easier mechanism to help determine scales that you would like to see added in MapServer then please share them... I'd be happy to help improve this. I always setup a trivial OpenLayers viewer with the scale control turned on and it displays the scale over the map. This has the benefit, that I can make changes to the mapfile and see them in OL by just a slight pan to refresh the map. I use singleTile: true, ratio:1 on the layer. This has the advantage of bringing the scale value and the map together so you can better visualize the changes and see the effect of changes. -Steve W ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-users] Raster Strategies Examples
Jan Hartmann wrote: > > Would it make sense to add this functionality to MapServer? Finding > scale breakpoints is a hassle indeed! > Jeff McKenna wrote: > I've always used a simple CGI template containing the [scaledenom] parameter. > I plan to simplify this for MS4W users. Jan, Jeff, If you have ideas of an easier mechanism to help determine scales that you would like to see added in MapServer then please share them... I'd be happy to help improve this. -- Daniel Morissette http://www.mapgears.com/ ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-users] Raster Strategies Examples
- How can i calculate the scale where i should create another layer of the tiles, or i shoud see it with some tests? I find the MapServer scale values very confusing myself. If I want to compute the scale for particular request (for instance to establish breakpoints for MINSCALE/MAXSCALE), I do a request at the target resolution with shp2img and debug output on and examine the debug output for the scale reported. I've always used a simple CGI template containing the [scaledenom] parameter. I plan to simplify this for MS4W users. -jeff -- Jeff McKenna MapServer Consulting and Training Services http://www.gatewaygeomatics.com/ ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-users] Raster Strategies Examples
On 08/03/10 14:12, Frank Warmerdam wrote: I find the MapServer scale values very confusing myself. If I want to compute the scale for particular request (for instance to establish breakpoints for MINSCALE/MAXSCALE), I do a request at the target resolution with shp2img and debug output on and examine the debug output for the scale reported. Would it make sense to add this functionality to MapServer? Finding scale breakpoints is a hassle indeed! Jan ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-users] Raster Strategies Examples
Folks, I'm sorry for speaking up on this without having read the other replies. Forgive me for repeating information. Edi.Karadumi wrote: as you may know, i have very slow performance when i zoom out and im stucked here. As i have read i should make a copy of the tiles with reduced resolution. Merge the tiles together and use min/max scale to show different layers in different scales. the min/max scales i zoom in/out are 100/120. Now my questions are - How can i calculate the scale where i should create another layer of the tiles, or i shoud see it with some tests? I find the MapServer scale values very confusing myself. If I want to compute the scale for particular request (for instance to establish breakpoints for MINSCALE/MAXSCALE), I do a request at the target resolution with shp2img and debug output on and examine the debug output for the scale reported. - how much should be the resolution of the new layer? You basically want to move to a new mosaiced overview layer at the point where a map request is likely to request several tiles at once. If we, roughly, assume a map request is on the order of 500x500 then at 32 times reduction in resolution would give a request over an area of 16000 x 16000 which is certain to touch several of your 6000 x 6000 base files. So, I'd aim to have this merged mosaic at approximately 1/32nd of the resolution of the original imagery. 1200GB of full res imagery reduced to 1/32nd resolution is only about 1GB so it is a very managable size for an overview layer. - is there any tools or program to merge the tiles? merging 6000 tiles with the gdalwarp by writing the command by myself is frustrating gdalwarp can take multiple input files in one run, but there are some issues with how gdalwarp is implemented that make it not scale well to many input files without great care. Since the input files are quite a modest size I would suggest using gdal_merge.py to mosaic them at a reduced resolution. If your original imagery were 5m pixels something like: gdal_merge.py -o overview_mosaic.tif -ps 160 160 */*.tif might do the trick. - how many tiles should i merge together to create the new layer? (how many tiles should have the new layer) i know that in each zoomscale its better to appear only one tile but i dont know how to calculate it - the tiles that i should merge are the originals or those with internal tiling and overviews? If you use gdal_merge.py, it is best to use input files that have overviews already built. This will ensure that the mosaic built uses the same downsampling technique (ie. averaging) that you used to build the overviews. It will also make the mosaicing much faster. Best regards, -- ---+-- I set the clouds in motion - turn up | Frank Warmerdam, warmer...@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush| Geospatial Programmer for Rent ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
[mapserver-users] Raster Strategies Examples
I have read many strategies for raster performance, but i still have problems with my case. The posts that i have read explain the strategie, but are not very detailed. Im new to mapserver so i have problems implementing them. My case is: -about 6000 tiles that form the map -170mb each tile -aproximately 1.2T of iamges -i have 10T HD and i think disk space is not a problem for me -tile format is TIF -tile size 9375x6250 pixels The strategy i have implemented and the problems i have -First i divided the tiles in 60 folders, to increase the performance in disk seek/read. -Than i transformed source files into internally tiles with the command gdal_translate -of GTiff -co "TILED=YES" original.tif tiled.tif -i used gdaladdo to add internal pyramids gdaladdo -r average 2 4 8 16 32 64 128 -Created a tileindex using gdaltindex -write_absolute_path MapAll.shp //server/Maps/Subfolder1/*.tif -Created a spatial index .qix file shptree MapAll.shp -than added the layer to the mapfile without the .shp extension so the application can use the .qix as you may know, i have very slow performance when i zoom out and im stucked here. As i have read i should make a copy of the tiles with reduced resolution. Merge the tiles together and use min/max scale to show different layers in different scales. the min/max scales i zoom in/out are 100/120. Now my questions are - How can i calculate the scale where i should create another layer of the tiles, or i shoud see it with some tests? - how much should be the resolution of the new layer? - is there any tools or program to merge the tiles? merging 6000 tiles with the gdalwarp by writing the command by myself is frustrating - how many tiles should i merge together to create the new layer? (how many tiles should have the new layer) i know that in each zoomscale its better to appear only one tile but i dont know how to calculate it - the tiles that i should merge are the originals or those with internal tiling and overviews? -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/Raster-Strategies-Examples-tp5363321p5363321.html Sent from the Mapserver - User mailing list archive at Nabble.com. ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
