WMS Server serving large raster

[Milo van der Linden]

Ed,
 
Thank you for the response! 
 
I indeed found the needed documentation on TILEINDEX and will try to create
it with gdaltindex. My raster images are however overlapping, will this
cause problems for the TILEINDEX since I think I remember that ESRI shape
files do not support overlapping objects (MapInfo does)?
 
Will the requested 100x100 image be rebuild with every request sent from a
WMS client to the server? Because I tried it with a single Raster Image in
MapInfo via WMS Server and zooming in and out resulted in a loss of raster
quality because the raster remained in the resolution it had when it was
first connected.
 
Kind regards!

  _____  

From: Ed McNierney [mailto:ed at topozone.com] 
Sent: woensdag 3 augustus 2005 14:43
To: Milo van der Linden; MAPSERVER-USERS at LISTS.UMN.EDU
Subject: RE: [UMN_MAPSERVER-USERS] WMS Server serving large raster


Milo -
 
This kind of application isn't any problem at all.  It sounds like your base
rasters are a collection of tiled data all belonging to the same data set.
You can use the gdaltindex utility from GDAL to create a shapefile index of
your rasters, and then use the TILEINDEX statement in your LAYER definition
to refer to that tile index file.  MapServer will, for any given request,
use the tile index file to determine which input rasters are needed, read
the correct data from each image, produce the requested 100x100 output image
and send it to the client.
 
To specifically answer your three questions:
 
1. Use a tile index as described.  There are other things you can do to tune
the internal format of each raster file.  What file format do your rasters
use?  Do you have the freedom to modify that file format, or do you have to
use them as they are?
2. MapServer will deliver a WMS image response that includes only the data
you need.
3. The tile index will give you the most compact map file.
 
    - Ed
Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242 


  _____  

From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Milo van der Linden
Sent: Wednesday, August 03, 2005 5:02 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: [UMN_MAPSERVER-USERS] WMS Server serving large raster


Hello list,
 
I have set up my first WMS Server and joined it with my standard MapInfo
client, all works well. I am facing the following challenge however:
 
- I have over 1,5Gb of raster image data covering the whole of the
Netherlands at a 1:25000 scale. I want to serve this data via my MapServer
WMS Server in order to get it into my WMS capable smartphone GPS viewer.
Since my phone holds limited memory, I want the rasters to be sent accross
the air smart, meaning that only for the resolutions displayed (100x100)
that part of the image should be sent.
 
My base rasters are 5000x5000 pixels and about 5mb in size, they are tiled
and all connect together or overlap.
 
 
In what way can I best organize my Map File in order to get: 
- Highest performance on my smartphone
- only the detail that I need?
- The most compact Layer definition in the Map File?
 
Kind regards,
Milo van der Linden 
AVD-ICT GIS Consultant 

*	Hoogbloklandseweg 24 

*	4205 NE  Gorinchem

Tel. +31 183 50 81 50 
Fax. +31 183 50 81 60 
Mob. +31 629 54 06 96 

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