[R-sig-Geo] importing file into GRASS via QGIS

[Jaime R. Garcia M.]

Patrick Giraudoux wrote:
> Dear all,
>
> I am using QGIS 0.11.0 Metis under windows and struggle to import a 
> raster into GRASS. This is an ARCINFO/ESRI grid file in natural 
> coordinates (WGS84) whose heading is:
>
> ncols  721
> nrows  360
> xllcorner  -180
> yllcorner  -90
> cellsize   0.5
> NODATA_value  254
>
> etc....
>
> I do not meet any trouble when importing it from QGIS as a raster, nor 
> within R using the package rgdal and the function readGDAL, but when 
> using within QGIS the GRASS importation tools (r.in.gdal or r.in.arc), 
> something goes wrong. Il looks like the vertical resolution was 
> respected (0.5), but the horizontal resolution unexpectedely comes to 
> be 0.000693481 in decimal degrees (making the map a narrow vertical 
> strip...), see the output of r.info below
>
> I get the same result reading a geotif  from QGIS/GRASS with 
> r.in.gdal. The geotif file was obtained reading the original ascii 
> raster from R  (everything OK), then writing it to a geotif with 
> writeGDAL().
>
> Any idea about what may happen ?
>
> Patrick
>
>
>
> ----------------------------------------------------------------------------+ 
>
> | Layer:    tempave                        Date: Sat Nov 28 11:07:22 
> 2009    |
> | Mapset:   giraudoux                      Login of Creator: 
> pgiraudo        |
> | Location: 
> ChinaWGS84                                                       |
> | DataBase: U:/Documents and Settings/pgiraudo/Mes 
> documents/GIS/grassdata   |
> | Title:     ( tempave 
> )                                                     |
> | Timestamp: 
> none                                                            |
> |----------------------------------------------------------------------------| 
>
> |                                                                            
> |
> |   Type of Map:  raster               Number of Categories: 
> 255             |
> |   Data Type:    
> FCELL                                                      |
> |   Rows:         
> 360                                                        |
> |   Columns:      
> 721                                                        |
> |   Total Cells:  
> 259560                                                     |
> |        Projection: 
> Latitude-Longitude                                      |
> |            N:        90N    S:        90S   Res:  
> 0:30                     |
> |            E:    179:30W    W:       180W   Res: 
> 0:00:02.496533            |
> |   Range of data:    min = 1.#QNAN0  max = 
> 1.#QNAN0                         |
> |                                                                            
> |
> |   Data 
> Description:                                                        |
> |    generated by 
> r.in.gdal                                                  |
> |                                                                            
> |
> |   
> Comments:                                                                
> |
> |    r.in.gdal -o input="U:\Documents and 
> Settings\pgiraudo\Bureau\TEMPER\   |
> |    AT\TEMPAVE.tif" 
> output="tempave"                                        |
> |                                                                            
> |
> +----------------------------------------------------------------------------+ 
>
>
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Dear Patrick,

Maybe the resolution of the current region in GRASS is set to the one 
you are getting when importing rasters. One should set the right 
resolution before importing.

g.region res=0:30
r.in.gdal -o input="U:\Documents and Settings\pgiraudo\Bureau\TEMPER\ 
    AT\TEMPAVE.tif" output="tempave" 

just an idea, hope it helps...

Jaime -R.