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

Patrick Giraudoux patrick.giraudoux at univ-fcomte.fr
Sat Nov 28 11:45:42 CET 2009


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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