Stefan,
I don't think you can specify 10'', you need something in pixels. But
the command is also probably not what you really need to do.
More likely, you should be doing the following:
gdal_translate -co "TILED=YES" gebco/bathymetry.tif gebco/
bathmetry_tiled.tif
This will create a single tif file that has an internal block size of
256x256 - you can think of this as having broken your tif up into
256x256 tiles but keeps them all within the same file. This is
equivalent to breaking the tif up into individual files, creating a
shapefile that has rectangles for each individual files' extent, and
using that as a tile index in mapserver.
Next, you want to do this:
gdaladdo gebco/bathymetry.tif 2 4 6 8 16
this will pre-compute smaller versions of the tif image called
overviews at 1/2, 1/4 1/6 1/8 and 1/16 of the original size of the tif
- this makes it much more efficient for gdal to return exactly what
mapserver is asking for at any given scale. Depending on the range of
scales that you need to display your raster image at, you can add more
overview levels (or take some away).
With this two commands, you can make your rasters much more efficient
for mapserver and probably avoid the need to split them up into many
files.
It does make the file somewhat larger. If you are working with very
large files ( > 4GB ) then you may run into some problems with tiff
and may need to investigate another format or a compressed format like
ECW or MrSID (both requiring commercial licenses I believe).
There are also some built in compression schemes for tiffs in gdal
which you can apply when running gdal_translate (see http://www.gdal.org/frmt_gtiff.html
for creation options), for instance:
gdal_translate -co "TILED=YES" -co "COMPRESS=JPEG" -co
"JPEG_QUALITY=80" gebco/bathymetry.tif gebco/bathmetry_tiled.tif
would compress the tif using JPEG compression (lossy) set to 80% (low
compression, small loss).
Cheers
Paul
On 18-Apr-08, at 5:47 AM, Stefan Schwarzer wrote:
Thanks for the info.
Did it like this:
Library/Frameworks/GDAL.framework/Versions/1.5/Programs/
gdal_translate -outsize 10'' 10'' -co TILED=YES gebco/bathymetry.tif
gebco/bathymetry_tiled.tif
But get the message: "Segmentation fault"
Anything that I did wrong? Or should do differently?
Thanks for a hint,
Stef
Hi,
Gdal_translate program has options for you:
c:\FWTools>gdal_translate
Usage: gdal_translate [--help-general]
[-ot {Byte/Int16/UInt16/UInt32/Int32/Float32/Float64/
CInt16/CInt32/CFloat32/CFloat64}] [-strict]
[-of format] [-b band] [-outsize xsize[%] ysize[%]]
[-scale [src_min src_max [dst_min dst_max]]]
[-srcwin xoff yoff xsize ysize] [-projwin ulx uly lrx lry]
[-a_srs srs_def] [-a_ullr ulx uly lrx lry] [-a_nodata value]
[-gcp pixel line easting northing [elevation]]*
[-mo "META-TAG=VALUE"]* [-quiet] [-sds]
[-co "NAME=VALUE"]*
src_dataset dst_dataset
By playing with -srcwin or possibly with -outsize and -projwin you
should be able to split your image as you wish. Read more from
http://gdal.org/gdal_translate.html
-Jukka Rahkonen-
Lähettäjä: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
] Puolesta Stefan Schwarzer
Lähetetty: 18. huhtikuuta 2008 12:05
Vastaanottaja: mapserver-users@lists.osgeo.org
Aihe: [mapserver-users] How to tile a large TIF image?
Hi there,
I would like to use instead of single large tif image smaller
tiles. Although I am well aware of mapserver's and gdal's
possibilities to create the shapes for it, I first need to "split"
the large tif into 20 or 50 or 100 tiles.
Can anyone give me a hint with what kind of software this is
possible?
There is an ArcGIS script, but it doesn't work on my machine ( http://arcscripts.esri.com/details.asp?dbid=13978
).
Thanks for any hints,
Stef
____________________________________________________________________
Stefan Schwarzer
Lean Back and Relax - Enjoy some Nature Photography
http://photoblog.la-famille-schwarzer.de
Appetite for Global Data? UNEP GEO Data Portal:
http://geodata.grid.unep.ch
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Paul Spencer
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DM Solutions Group Inc
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