Robert Coup wrote
On Sat, Aug 15, 2009 at 10:57 PM, Hermann Peifer <pei...@gmx.eu> wrote:
I have the same observation while working with ASTER GDEM tiles (1x1 degree
tiles, 3601x3601 pixel each). When warping/merging, say: 10 tiles into a
single outfile.tif, then it takes gdalwarp around 5 seconds per tile to do
the job:
Does creating a tiled tiff (-co TILED=YES) make any difference? It should
improve random access, which is what writing new data to image blocks is.
Thanks for the hint, but I didn't make any substantial difference, as far as I
could see.
Basically, my task is to warp/resample/merge some 1500 ASTER GDEM tiffs into a
single output file in LAEA projection. My area of interest is around 5000 x
4000 km, i.e. my 100m output raster would be 50000 x 40000 x 16 bit/pixel = 4GB
GeoTiff.
I thought this should be a doable task and would perhaps take some hours or so.
But over the last days, I have been experimenting quite a lot with -wm,
--config GDAL_CACHEMAX settings, etc. without getting anywhere apart from the
insight that it would take 10 days and more to do the job. I have a vague
feeling that I am overlooking something obvious.
A promising approach seemed to be to warp/resample the ASTER files one by one
and create 1500 separate tiles in LAEA projection, as an intermediate step.
Then I created a vrt file with gdalbuildvrt and gdal_translated it into tiff
format. The result did however look odd, as the elevation data in most tiles
was clipped by NODATA areas of their neighbouring tiles :-(
Hermann
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