[gdal-dev] Re: CUDA PyCUDA and GDAL

[Rahkonen Jukka]

>  <Doug_Newcomb <at> fws.gov> writes:
> 
> Hi Folks,Here's the gdal command (gdal 1.6.2) I used to merge ~3500 1
meter NAIP
> quarter quads (uncompressed geotiff TIFF) in 3 UTM projections into
one Bigtiff Image
> in the USGS Albers projection.  It took about 15 hours ( on a 3 year
old Intel Core2
> Duo 64 bit Centos 5.3 Linux box with 6GB RAM) and created an
uncompressed, tiled,
> bigtiff file of 485 GB. About 32 GB/hr.
> gdalwarp -t_srs "+proj=aea +lat_1=29.5+lat_2=45.5 +lat_0=23.0
+lon_0=-96 
> +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m no_defs <>"
> -wo "SKIP_NOSOURCE"  --config "GDAL_CACHEMAX=500" -wm=5000
> -co "TILED=YES" */*.tif /biggis/albers/nc_naip2008.tif
> 
> In the above command, -t_srs "+proj=aea +lat_1=29.5 +lat_2=45.5
+lat_0=23.0 
> +lon_0=-96 +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m no_defs
<>"
> indicates the target projection, -wo "SKIP_NOSOURCE" don't write
> in areas for which there is no data for the current file, 
> --config "GDAL_CACHEMAX=500" set the cache memory at 500MB ( set this
close 
> to the maximum input file size), -wm=5000 set the warp memory to
5000MB ,
> -co "TILED=YES" create a tiled tiff as output, */*.tif, use all of the
tiffs 
> in all of the subdirectories as input files ( in this case there was
one 
> directory for each of the 3 utm zones) ,
/biggis/albers/nc_naip2008.tif,
> the output file name and location. 
> 

Hi Doug,

I finally tried your parameters and they did work fine for me also.  I
had something like  hundred geotiffs, 400 MB each, and I was pushing
them to bigtiff mosaic. I tried first with your *.tif selection and then
again by using a virtual raster file as source, created from Mapserver
tileindex shapefile with gdalbuildvrt. My Windows computer was handling
about 20 GB/hour with cubic resampling (-rc) this time.  Parameters 
-wo "SKIP_NOSOURCE"  --config "GDAL_CACHEMAX=500" -wm=5000
seem to have a big influence on efficiency.  I wonder if there are some
rules of thumb for selecting values of GDAL_CACHEMAX and -wm.  You said
cachemax is good to be close to the maximum input file size, how about
-wm?

-Jukka Rahkonen-