Ciao Paul,
first of all, where to place JAI and ImageIO native libs. I usually
put them in %JAVA_HOME%/bin but anyway make sure that wherever you put
them, they are in a path, that is inlcuded in the PATH env var or they
won't be picked up.
As far as your mosaic is concerned, I have a few suggestions; note
that I am assuming you are using geotiff files.
You have a great number of not-so-small files. If you want to see a
speed-up without actaully spending to much time on it, add overviews
to each single image, You can use gdaladdo tool to do that or I can
give you instructions to do it with geotools. This would be the lowset
hanging fruit but I can tell you that it might suffice.
The problem I see with yor mosaic is that it contains a considerable
number of images (not bigh though). If you keep it this way you will
always pay a certain penalty because ou will keep on opening a certain
number of files when you are really zooming out. The best thing would
be re-tile your mosaic in order to obtain fewer but bigger tiles and
the add overviews to them. As an alternative I would see using a
pyramid which would solve the problem discussed above since it shrinks
the number of files as the resolution decreases. The tools to build
the pyramid were not so stable so far, but we are working on them and
next week we should release some imporvements.
Hope that helps,
Simone.
On Dec 6, 2007 7:58 PM, Paul McCullough <Paul.McCullough@anonymised.com> wrote:
All,
I have set up an image mosaic.
It seems slow.
What can I do to make it faster?
My web browser rendering speeds are shown in the table below.
secs secs
to to
render render
scale raster vector
1:6000 15 3
1:3000 15 3
1:1500 5 3
1:800 3 2
1:400 3 2
1:200 2 2
I am happy with the 2-3 second time range but the value of the image is
really around the 1:6000 scale.
Fifteen seconds seems too slow.
There is no TileCache; I plan to set one up very shortly (today?).
I am running:
- Geoserver 1.5.4 "out of the box" with Openlayers
- heap space is set to -Xmx512m; of which I never get past about 300m
- windows XP SP 2 with 2GB RAM
- jdk1.6.0_02
- I have installed the JAI native acceleration (details below)
- vector data is being served out of PostGIS
The image mosaic consists of 254 files; each file is 5.7 MB (total of about
1.5 GB)
Each file is a 3000x2000 pixel orthophoto.
The shapefile has a spatial index.
Just in case...here is my SLD for the image mosaic:
<?xml version="1.0" encoding="UTF-8"?>
<StyledLayerDescriptor xmlns="http://www.opengis.net/sld"
xmlns:ogc="http://www.opengis.net/ogc"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.opengis.net/sld
http://schemas.opengis.net/sld/1.0.0/StyledLayerDescriptor.xsd"
version="1.0.0">
<UserLayer>
<Name>raster_layer</Name>
<LayerFeatureConstraints>
<FeatureTypeConstraint/>
</LayerFeatureConstraints>
<UserStyle>
<Name>raster</Name>
<Title>A boring default style</Title>
<Abstract>A sample style for rasters</Abstract>
<FeatureTypeStyle>
<FeatureTypeName>Feature</FeatureTypeName>
<Rule>
<MaxScaleDenominator>15000</MaxScaleDenominator>
<RasterSymbolizer>
<Opacity>1.0</Opacity>
<OverlapBehavior>
<AVERAGE/>
</OverlapBehavior>
<ShadedRelief/>
</RasterSymbolizer>
</Rule>
</FeatureTypeStyle>
</UserStyle>
</UserLayer>
</StyledLayerDescriptor>
So...if I want this this to run faster, what should I do?
Should I debug the code to see what is taking the extra time?
Should I change the mosaic?
In the end, I expect to be building a pyramid; but for now
I am leaning towards building another single mosaic with smaller tiles.
Are there optimum tile sizes for each scale?
Should I make sure I am using the native accelration?
I did make the "Could not load mediaLib accelerator wrapper classes.
Continuing in pure Java mode." stack trace go away.
Is that a sure sign that I am using the native accelration?
I put the DLLs here C:\Program Files\Java\jdk1.6.0_02\jre\bin
JAVAHOME is here C:\Program Files\Java\jdk1.6.0_02
Should I just start using TileCache and not worry about optimzation in this
layer?
Thanks,
Paul McCullough
City and County of San Francisco
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