[GRASS-user] [r.resample] null values for min and max range of data values

[Markus Neteler]

On Thu, Feb 25, 2010 at 9:21 AM, baobazz <baobazz at hotmail.fr> wrote:

... (welcome!)...

> Initially, I wanted to vectorize an image
> After having imported it, I tried to thin it through the r.thin command.
> But the image produced being too big, it caused errors on my computer.

What kind of error exactly? You seem to use Windows, which version
of GRASS?

> To solve my problem, I decided to reduce my location resolution: res=2, then
> that of my raster with r.resample...
>
> The problem is that my resampled raster output is empty.
> When typing r.info raster.resampled, I get:
> r.info raster.resampled2
>
...
>  |   Type of Map:  raster               Number of Categories: 0
>  |   Data Type:    CELL
>  |   Rows:         500
>  |   Columns:      500
>  |   Total Cells:  250000
>  |        Projection: Lambert Conformal Conic
>  |            N:    6133000    S:    6132000   Res:     2
>  |            E:    1235000    W:    1234000   Res:     2
>  |   Range of data:    min = NULL  max = NULL
...
>  |    r.in.gdal input="C:/tests/GRASS/rasterToVect/BDP_08_1234_6134_010_L9\
>  |    3.tif" output="raster"

...
> What is strange is the null range of data...

Yes, no good.

> The r.info for my raster input, not resampled is:
> r.info raster6133_2
...
>  |   Rows:         10000
>  |   Columns:      10000
>  |   Total Cells:  100000000

(same position)

>  |   Range of data:    min = 0  max = 1

One thing I don't understand: Why do you use r.in.gdal after
r.resample? Please outline the workflow to be better able to
help you.

Markus