[Mapserver-users] Tiling Tif Images

[Jan Hartmann]

I do this routinely with GRASS. If you have never worked with it it will 
take you some time to install and learn it, but IMHO the time is well 
spent. Once you have things running tiles can be made in three steps:

- import the image using r.in.gdal
- set the region to the tile you want to generate
- r.resample input=<imported image> output=<tile>
- export the image using gdal_translate

The beautiful thing about GRASS is that you can script everything using 
ordinary shell scripts. I have been tiling Gigabyte rasters this way in 
matters of minutes.

As to tile size, I generally create tiles of 2000*2000 pixels. An 
original raster of 40000*40000 pixels gets divided into 400 tiles this 
way, and this gives quick response. I haven't done much experimenting 
much with this however. Did anyone on the list ever experiment with 
different tile sizes on the same raster basemap? If you make the tiles 
larger, it takes longer to extract the region; if you make them smaller, 
chances are greater that MapServer has to combine several tiles to 
generate the image. I don't know where the optimum lies.

Jan

Stefan Schwarzer wrote:
> Hi list,
> 
> hmm, I think I read everything concerning the tiling of raster images by 
> now. But the best hint I've found was the following URL ( 
> http://remotesensing.org/gdal/gdal_utilities.html ). I read as well this 
> document ( http://mapserver.gis.umn.edu/doc/raster-howto.html ), but no 
> solution in sight. I tried to find the gdaltindex (for windows), but did 
> not succeed. I have the OpenEV installed, but this does not offer tiling.  
> 
> Fact is: I have several dozens of raster images which are mostly between 
> 100 and 500 MB. So, would you recommend to do some tiling with these 
> sizes? If yes, what tool should I use?
> 
> 
> Can someone give be a tip?
> 
> Thanks,
> 
> Stefan
> 
> 
>         _______________________________________
> 
>         *Stefan Schwarzer
> *        Consultant on GEO
> 
>         UNEP/DEWA/GRID-Geneva
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> 
>         Tel: (+41) 22.917.83.49
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> 
>         Email: stefan.schwarzer at grid.unep.ch
>         Internet: http://geodata.grid.unep.ch/
>         _______________________________________
>