[Mapserver-users] Tiling a large raster

[Lars V. Nielsen]

Hi Matthew,

I've seen some "splitting" tools in connection to small web page graphics, but I doubt that they can handle Gb large rasters.

Wrt. ECW, there was a small bug in the ECW support, but it was fixed on Dec. 20 last year. Since then I've been using ECW with great
success.
One caveat is that Mapserver 3.6.x only supports 8 bit color internally (due to GD version 1.x I've been told), so you'll need 3.7
to have the full benefit of any 24 bit ECW or TIFF images.

I've set up two editions of basically the same MAP file showing an ECW mosaic, one using 3.6.3/GIF and another using 3.7/JPEG. The
difference is noteworthy:
3.6.3/GIF: http://gis.hvm.dk/svendborg/sample.php?mapfile=svendborg.map&version=36
3.7/JPEG: http://gis.hvm.dk/svendborg/sample.php?mapfile=svendborg37.map&version=37

ECW is actually a great format for mosaics, the one used above is also about 3.5 Gb. It performs splendidly, until one gets below
scale 1:2000 or so. Then the rendering slows down considerably. So if applicable, you shouldn't need to bother with tiles at all, if
you can convert your GeoTIFF file to ECW instead.

And please do note that ECW is Windows-only.

Best regards/Med venlig hilsen
Lars V. Nielsen
GisPro, Denmark
http://www.gispro.dk/
http://hjem.get2net.dk/lars-online/
WGS84: 10.20'40"E 55.20'20"N
----- Original Message -----
From: "Matthew Hatcher" <MJHatcher at space.qinetiq.com>
To: <mapserver-users at lists.gis.umn.edu>
Sent: Tuesday, February 25, 2003 11:10 AM
Subject: [Mapserver-users] Tiling a large raster


> Hi all,
>
> I have several massive GeoTIFF rasters (talking 3.5GB each here), and would
> really quite like to tile them to make them a little easier to handle.
>
> I've seen the GDAL tileindex application which takes a set of tiles and
> builds a shapefile index, but is there any tool out there that will take a
> massive raster and split it up into georeferenced chunks (doesn't have to be
> GeoTIFF, just something that Mapserver can read)?
>
> Whilst on the subject, the ECW format would seem to be a more sensible
> storage format than the GeoTIFF. The documentation on this format is a
> little sketchy - is it an option that can be turned on with configure or
> does it come as part of one of the other filters eg. GDAL? If anybody's used
> it I'd appreciate some pointers.
>
> Cheers,
> Matt.
>
>
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