[gdal-dev] Process many DEM's into 1

[Matt Wilkie]

Hi Courtney, Oliver,

 > I would try to do:
 >
 > gdalwarp <file1> <file2> ... <outputfile>

Depending on the source data, this may not handle overlap between tiles 
very well. For the canadian CDED dems from geobase.ca I had to use the 
src and dstnodata options:

   gdalwarp -srcnodata -32767 -dstnodata -32767 ...etc

It can also speed up things dramatically to use the -wm and -multi 
options (working memory and multithreaded).

Some scripts I used are at 
http://sydney.freeearthfoundation.com/mattwilkie/draft/canada_50k_dem/scripts/

(Unlike the script there, don't use "-co compress=lzw" though! it will 
make your images larger than if no compression is used. 
http://trac.osgeo.org/gdal/wiki/UserDocs/GdalWarp#a-coCOMPRESSisbroken )

cheers,

matt wilkie
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Oliver Eichler wrote:
> On Tuesday, 8. July 2008 17:42:07 Courtney Schitka wrote:
>> Hi List,
>>
>> You guys have been great. Today my problem is I've downloaded 400 dem's
>> from an FTP server I was wondering if there was anyway using FWTools or
>> what have you, to turn many dem's into 1 dem. The files are seperate and
>> together cover one contiguous area. Rather then opening every one I would
>> like to turn them into 1 file so all i have to do is open 1 of them.
>>
> 
> I would try to do:
> 
> gdalwarp <file1> <file2> ... <outputfile>
> 
> Oliver
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