Hi Jukka Thanks for the response and the great investigative work! My log entry for drawing the layer is - [Fri Sep 03 10:01:25 2010].658000 msDrawMap(): Layer 1 (meanspringpeakflow), 24.500s. :o(
I do wonder if my Mapfile layer definition is just v.poor (admittedly no expert!) so have taken an excerpt of the layer defintion (there are about 15 classes in all) - views anyone, should I be loading it a different way? Also Jukka, could I get a sample of your scale dependent WMS GROUP layer map code - as it sounds like a great idea maybe for this but also some v.hi-res model grids I am thinking about. Thanks again, much appreciated! Chris LAYER NAME "meanspringpeakflow" TYPE polygon DEBUG 5 DATA "Tide" TEMPLATE void PROJECTION "+proj=utm +zone=31 +ellps=GRS80 +units=m +no_defs" END METADATA "DESCRIPTION" "Mean Spring Peak Flow" "RESULT_FIELDS" "ID,DISTANCE,DEPTH,MEAN_SP_PC" "RESULT_HEADERS" "ID,Minimum Distance (m),Average Depth (m),Mean Spring Peak Flow (m/s)" "ows_title" "meanspringpeakflow" "RESULT_HYPERLINK" "ID|| Load graphing tool" END # Metadata CLASS NAME '> 4.00 (m/s) ' EXPRESSION ([MEAN_SP_PC] >= 4 AND [MEAN_SP_PC] < 4.5) STYLE COLOR 135 99 64 END #end style END # end class CLASS NAME '3.51 - 4.00' EXPRESSION ([MEAN_SP_PC] >= 3.5 AND [MEAN_SP_PC] < 4) STYLE COLOR 158 126 63 END #end style END # end class etc etc On 3 September 2010 09:04, Rahkonen Jukka <jukka.rahko...@mmmtike.fi> wrote: > Hi, > > I took some numbers to compare with. > > Material and methods > > Polygon layer, rather simple polygons with few vertises, Feature Count: > 117383 > DEBUG 5 in mapfile > WMS client asks for the whole layer > Mapserver 5.2.1 (CGI) on not so fast Windows computer > Results > First request: rendering time taken from the log file are between 3.5 and > 4.5 seconds > Following request, BBOX is changing but all the polygons are drawn though: > rendering times 1.5 - 2.5 seconds > > Conclusions and discussion > At first one might think that my server is faster. But this test is not > controlled at all because we are not using the same shapefiles and we can't > say so. What we can say that a couple of hundred of thousand polygons can be > drawn faster. > > However, it does not really make sense to render an image this way if it > should be fast. If the screen has 1000 by 1000 pixels it makes a million > pixels together. For 200000 polygons it makes 5 pixels per polygon. You > can simplify your polygon geometries pretty much before anybody can see the > differense. If the polygons are spread evenly nobody can even see the > difference if there are 20000 or 200000 polygons on the screen. > > We have one polygon layer with about million polygons and for that I made > two simplified layers which contain only 1 percent and 10 percent of all the > polygons. Those and the original shapefile are put into the same scale > dependent WMS GROUP layer. This group is pretty fast at any scale. The 1 > percent layer is perhaps a bit too sparse but I have been too lazy to have a > try with 2 or 5 percent samples. > > -Jukka Rahkonen- >
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