[gdal-dev] Re: gtiff file size compared to original tiff +wrld file

[Christian Müller]

Hi, I did this process last year many times and here is my experience 

1) I assume you omitted the create options, your original tiff files are 
compressed, the new ones not.
Look here http://www.gdal.org/frmt_gtiff.html, on the commandline it is  -co 
"COMPRESS=JPEG" as an example. 

2) Take a look at your tiles with gdalinfo, do the have a color table or 
more bands ?. If your tiles have
more bands, (e. g. one for read, one for green and one for blue), use 
gdal_merge.py with -pct to produce a big picture
having only one band and a color table. Create your tiles from the big 
picture. Geoserver will say thank you in terms
of memory usage and cpu performance. 

3) Decide, wich Geoserver module to use. There are 2 of them. There is a 
file based approach and a jdbc based
approach (Module imagemosic-jdbc). If you want to store the whole stuff in a 
database, use gdal_retile.py to procude your
tiles and pyramids and the imagemosic-jdbc module to import all the tiles. 
Both, gdal_retily.py and the imagemosaic-jdbc
module were developed by me, if you have questions, ask. 

The documentation is here 
http://docs.codehaus.org/display/GEOTDOC/Image+Mosaicing+Pyramidal+JDBC+Plug 
in
A tutorial for geoserver is here 
http://geoserver.org/display/GEOSDOC/Using+the+ImageMosaic+JDBC+Plugin 

christian 


TJMartin writes: 

> 
> Hi All 
> 
> I am just getting started with gdal, and i have done a search but couldnt
> find an answer. 
> 
> I currently have 10,000 tiff files with their world files. My real aim is to
> tile them up and make them easier to use in Geoserver or create an image
> pyramid. 
> 
> So i used gdal_translate to Geotiff, then was going to use gdalwarp to
> mosaic, then tile them. 
> 
> However the file size for geotiffs are between 4 and 15 times the size 
> 
> 4mb to 60mb 
> 
> One set were originally 128mb and now 858mb. 
> 
> So if i was to mosiac these and then tile them it will still be a huge
> data/size volume to server via geoserver. 
> 
> 
> So my questions 
> 
> 1) Can i reduce the quality when translating to geotiff, and how much will
> this affect the image quality when i mosaic and tile 
> 
> 2) Should i mosaic the tiff + world files instead and then tile them with
> world files instead of using geotiffs 
> 
> 3) is there  a better way of doing this? 
> 
> would really appreciate anyone's help 
> 
> all the best 
> 
> Tim 
> 
> -- 
> View this message in context: http://n2.nabble.com/gtiff-file-size-compared-to-original-tiff-%2Bwrld-file-tp2672921p2672921.html
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> 
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