[GRASS-user] How to crop away NODATA margins

GRASS GRASS user
,
1

Hi,

I see that d.out.file has a switch: -m (Do NOT crop away margins). So I assume that by default, white margins are auto-cropped.

What I am looking for is some sort of auto-crop feature which I could use with r.out.gdal, in order to get rid of abundant NODATA margins in raster layers.

What I am currently doing: I identify a raster layer's data extent visually before changing the region and then running r.out.gdal. However, I might miss some islands at the edges...

Thanks in advance, Hermann

2

Hermann Peifer wrote:

Hi,

I see that d.out.file has a switch: -m (Do NOT crop away margins). So I assume that by default, white margins are auto-cropped.

What I am looking for is some sort of auto-crop feature which I could use with r.out.gdal, in order to get rid of abundant NODATA margins in raster layers.

g.region zoom=<myrast> align=<myrast> ?

Markus M

3

Hermann wrote:

I see that d.out.file has a switch: -m (Do NOT crop
away margins). So I assume that by default, white margins
are auto-cropped.

IIRC it depends on the output type.
I can't remember how many methods I exteneded that to.

What I am looking for is some sort of auto-crop
feature which I could use with r.out.gdal, in order to get
rid of abundant NODATA margins in raster layers.

g.region rast=your_map
g.region zoom=your_map
r.out.gdal ...

d.out.file is just a shell script, you can look in it for
the commands used to figure out the cropping. (I expect d.info
and g.region)

What I am currently doing: I identify a raster layer's data
extent visually before changing the region and then running
r.out.gdal. However, I might miss some islands at the
edges...

try 'g.region zoom='

Hamish

4

g.region zoom=<myrast> align=<myrast>

I overlooked this in the documentation, I have to admit :frowning:

Sorry for the noise and thanks to both of you. Hermann