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List:       mapserver-users
Subject:    Re: [mapserver-users] It takes more than 2 minutes for my map
From:       Rahkonen Jukka <Jukka.Rahkonen () mmmtike ! fi>
Date:       2011-07-28 16:04:22
Message-ID: 84446DEF76453C439E9E97E438E13A63015BE5 () suutari ! haapa ! mmm ! fi
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Hi,

It is really essential to avoid opening all the 4659 files.  Redused resolution \
overview images and layer group is the way to go so that there are never more than, \
let's say, 20-30 images to open for one call.  And gdaladdo does help further.  And \
the third step is to have internally tiled image files.  When zoomed in so that just \
a minory part of the image file is needed for generating the output tiling helps in \
getting the desired part of an image fast.

Mapserver itself can be used for creating overview images, just define a geotiff \
outputformat (http://mapserver.org/mapfile/outputformat.html) and make some requests \
with well controlled BBOXes.  

-Jukka Rahkonen-

Stephen Woodbridge wrote:

> You probably need to run gdaladdo to add reduced resolution overviews of
> you images which will speed up display when you are zoomed way out.

> for x in *.tif ; do
> gdaladdo $x 2 4 8 16 32 64 128 256
> done

> Regardless, to draw the whole world you will need to open all 4659 files
> and fetch something from each one. You can probably speed this up be
> creating a super overlay image at reduced resolution and setup you
> mapfile to use the super overlay when zoomed out and then change to the
> tiles when zoomed in.

> Read this might help:
> http://mapserver.org/optimization/raster.html

> Also the GDAL list will be able to help you on how to create a super
> overlay at reduced resolution.

-Steve W

On 7/28/2011 11:17 AM, Carlos Ruiz wrote:
> JK (?),
> 
> One question: did you use gdaltindex ?
> 
> IC Carlos Ruiz
> 
> *From:* jk <jk.chen@sdl.usu.edu>
> *To:* mapserver-users@lists.osgeo.org
> *Sent:* Wednesday, July 27, 2011 6:20 PM
> *Subject:* [mapserver-users] It takes more than 2 minutes for my map
> server to generate a world map
> 
> Hi,
> 
> I have a tile system of 4659 tiles, each is a 5 meter resolution raster
> image a particular spot in the world (as you know it is sparse, the
> collection of tiles do not cover the enter world).
> 
> When I asking for a map of the world (ie, high-level view, a bbox with
> values close to the lonlat boundary of the world), my map server
> consistently takes long time to finish, (close to 2.5 minutes, yeah,
> minutes, not seconds). This is very slow.
> 
> If I submit a bbox that matches a particular tile, the map is returned
> instantly.
> 
> How could it take so long to generate the world map?
> 
> How to fix that?
> 
> Anything I'm missing? Any idea?
> 
> I'm not using tile cache yet. But I think 2.5 minutes for world view is way
> too slow. Something must be wrong.
> 
> If you know of any clues, let me know.
> 
> Thanks for your help.
> 
> JK
> 
> 
> --
> View this message in context:
> http://osgeo-org.1803224.n2.nabble.com/It-takes-more-than-2-minutes-for-my-map-server-to-generate-a-world-map-tp6628127p6628127.html
>  Sent from the Mapserver - User mailing list archive at Nabble.com.
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