On 04/05/11 08:42, Hanlie Pretorius wrote:
> Hi Moritz,
>
> I'm not sure what you mean by 'Maris' first part of the solution'. I
> saw only one part to Maris's suggestion (refining the region's
> resolution) because I said in my initial mail that I had set extents
> of the region to the contours_20m vector layer. Initially I did have a
> resolution of 20m and got an empty raster layer as a result.
>
> I share Micha's confusion about this. Although it doesn't make much
> sense to have a 20m cell size (my bad) I would have thought that
> v.to.rast would still have given me an output.

Rereading the original mail I see this:

2011/5/2, Hanlie Pretorius<hanlie.pretor...@gmail.com>:
r.info for the result is:
| Layer: contours_20m@CDNGI_DEM Date: Mon May 02 14:18:00 2011
| Mapset: CDNGI_DEM Login of Creator: hanlie
| Location: SA_Lo_29E
| DataBase: F:\grassdata
| Title: Labels ( contours_20m@CDNGI_DEM )
| Timestamp: none
|----------------------------------------------------------------------------

|
| Type of Map: raster Number of Categories: 0
[snip]
| Rows: 1772
| Columns: 1750
| Total Cells: 3101000
| Projection: Transverse Mercator
| N: -3121229.69982072 S: -3156672.30728643 Res:
20.00147148
| E: -32474.90929218 W: -67483.27873573 Res: 20.00478254
| Range of data: min = 1620 max = 2460
[snip]       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

As you can see from the number of categories (0), there is no
information in this raster file.

There are no category values, but there are data values, so your map actually is not empty.

What does r.stats contours_20m@CDNGI_DEM give you ?

1) v.to.rast does create category labels by default. If you use the 'labelcol' parameter, then you get category values.

Example in the NC demo dataset:

v.to.rast elev_ned10m_cont10m out=contours col=level

r.info contours:

Number of Categories: 0
Range of data:    min = 60.000000  max = 150.000000

2) v.to.rast elev_ned10m_cont10m out=contours col=level labelcol=cat

r.info contours:

Number of Categories: 150
Range of data:    min = 60.000000  max = 150.000000

Moritz
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