[GRASS-user] Export the conversion from Vector to Raster

[Markus Metz]

Kim Besson wrote:
> Hi Markus
> I did this:
> r.out.gdal input=train_raster00 at PERMANENT
> output=C:\Data\GISDataBase\trainraster00b nodata=-1

nodata = -1 and type = Byte is no good because the range of Byte is 0
- 255 and -1 gets converted to 255, i.e. all NULL cells will become
255 (all cells that are already 255 stay 255) but nodata is -1 so info
about NULL cells gets lost.

> And I got
> <PROJ_INFO> not found for  <DATA>
> <PROJ_UNITS> not found for  <PT_IGP>

check the original Landsat data with gdalinfo. They are usually in
UTM. If the original data don't have projection info, the xy location
is correct and you have to manually reproject to a proper location. If
the original data do have projection info, something went wrong while
defining the location, no idea what.

Markus M

> Exporting to GDAL data type: Byte
> Unable to set projection
> Input raster map contains cells with NULL-value (no-data). The value -1 was
> used to represent no-data values in the input map. You can specify nodata
> value by nodata parameter.
> It's strange. Then I decided to do g.region display and I realized that:
> projection: 0 (x,y)
> zone:       0
> north:      23020.21492744
> south:      -190249.78507256
> west:       -52163.16923233
> east:       177696.83076767
> nsres:      30
> ewres:      30
> rows:       7109
> cols:       7662
> cells:      54469158
> (Fri May 07 10:40:07 2010) Comando terminado (0 sec)
>
> (Fri May 07 10:40:30 2010)
>
> g.region -p
>
> projection: 0 (x,y)
> zone:       0
> north:      23020.21492744
> south:      -190249.78507256
> west:       -52163.16923233
> east:       177696.83076767
> nsres:      30
> ewres:      30
> rows:       7109
> cols:       7662
> cells:      54469158
> I have NO PROJECTION :( How come? I have defined my Location from a
> projected Landsat image the same that I have imported. Any clues of what I
> did wrong?
> 2010/5/7 Markus Metz <markus.metz.giswork at googlemail.com>
>>
>> Kim Besson wrote:
>>
>> [snip]
>>
>> > 7- Now, export this raster.Since I want a Geotiff I used:
>> > r.out.tiff input=train_raster00 at PERMANENT output=trainraster00a
>>
>> You must use r.out.gdal to get a GeoTIFF, r.out.tiff produces an
>> ordinary tif image, not a spatial raster dataset.
>>
>> Markus M
>
>