[mapserver-users] How to tile a large TIF image?

[Stefan Schwarzer]

Thanks a lot for these details. That should be added to the existing  
documents!

But unfortunately I still get a "Segmentation fault" message...

Stef

> 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: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org 
>>> ] Puolesta Stefan Schwarzer
>>> Lähetetty: 18. huhtikuuta 2008 12:05
>>> Vastaanottaja: mapserver-users at 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
>   Chief Technology Officer
>   DM Solutions Group Inc
>   http://www.dmsolutions.ca/