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" | | | +----------------------------------------------------------------------------+
importing file into GRASS via QGIS
4 messages · Jaime R. Garcia M., Tom Gottfried, Patrick Giraudoux
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.
Hi Patrick, though this may have no effect on your problem: QGIS 0.11.0 is a very old version. Plus it might be more fruitful to ask on GRASS or QGIS lists/forums. Tom
Jaime R. Garcia M. a ?crit :
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