[mapserver-users] Display performance

[Chris Jackson]

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.Rahkonen at 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-
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/mapserver-users/attachments/20100903/dc78abe1/attachment.htm>