[GRASS-user] r.out.gdal

GRASS GRASS user
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1

Hi all,

I am exporting a 20m resolution raster to a GeoTiff using r.out.gdal. The raster (a DEM) covers Italy so I will get (at least I guess to) a very large file.
Export is currently at 20% and the file aorund 1GB.

Now, how can I pass (can I at all?) the ‘-outsize’ parameter to r.out.gdal to force a lower outsize for my GTiff?
Or I need a resampling?

thanx
raffaele

2

Raffaele Morelli wrote:

Hi all,

I am exporting a 20m resolution raster to a GeoTiff using r.out.gdal. The
raster (a DEM) covers Italy so I will get (at least I guess to) a very
large
file.
Export is currently at 20% and the file aorund 1GB.

Now, how can I pass (can I at all?) the '-outsize' parameter to
r.out.gdalto force a lower outsize for my GTiff?

You can't. But you can compress the r.out.gdal output providing a
createopt=string[,string,...] option.

See manual and the options available for paticular formats at
http://www.gdal.org/formats_list.html.

Or I need a resampling?

r.resamp.stats propably is propapbly the way to go

Maciek

3

GeoTiff has a creation limit of 4GB. Either you get the size below with some create options or you look for an other format. But it all depends whay you wanna do with the output.

Raffaele Morelli schrieb:

Hi all,

I am exporting a 20m resolution raster to a GeoTiff using r.out.gdal. The raster (a DEM) covers Italy so I will get (at least I guess to) a very large file.
Export is currently at 20% and the file aorund 1GB.

Now, how can I pass (can I at all?) the '-outsize' parameter to r.out.gdal to force a lower outsize for my GTiff?
Or I need a resampling?

thanx
raffaele

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4

Raffaele Morelli wrote:

I am exporting a 20m resolution raster to a GeoTiff using r.out.gdal.
The raster (a DEM) covers Italy so I will get (at least I guess to) a
very large file.
Export is currently at 20% and the file aorund 1GB.

try adding createopt="compress=packbits", and make sure you are not
using a data type= which is reporting to the 28th decimal place when the
DEM is really only accurate to the nearest meter. e.g. try type=Int16.

Hamish