Jaime R. Garcia M. a écrit :
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.
I have just tried with no success. Next trial will be to consider
Robert Hijmans' suggestion regarding the number of columns. Will come
back to the list for a report when done.
Thanks anyway for the hint,
Best,
Patrick
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