[R-sig-Geo] Problem reading back a raster from GRASS

[Pierre Racine]

Ok I passed "SG=image1" to initGRASS() and now I get the full extent of the image back.

Thanks Roger

>-----Original Message-----
>From: Roger Bivand [mailto:Roger.Bivand at nhh.no]
>Sent: 28 janvier 2011 14:59
>To: Pierre Racine
>Cc: r-sig-geo
>Subject: Re: [R-sig-Geo] Problem reading back a raster from GRASS
>
>On Fri, 28 Jan 2011, Pierre Racine wrote:
>
>> Hi,
>>
>> It seems I'm having problem storing a raster into GRASS using the
>> spgrass6 package. I writeRAST6() a 1376x1376 raster to GRASS, but when I
>> readRAST6() it back to R the raster is only 1x1 pixels... Note that the
>> raster is a bmp and hence is not projected to any coordinate system.
>>
>> I must be doing something wrong. Here is my R code:
>
>What is the current region of your GRASS location? You can check by
>looking at the output of gmeta6(). If it does not match the extent of the
>file, you may experience this. Have you checked the extent of the data as
>seem by GRASS before reading it back? Are you running R within GRASS or
>did you start GRASS with initGRASS() from within R? If you used initGRASS,
>did you use the SG= argument?
>
>Roger
>
>>
>> ------------------------------------------------------------------
>>> image1 = readGDAL("D:/temp/image01.bmp")
>>  D:/Clients/AlainPaquette/AnalyseDeCimeR/images/image01.bmp has GDAL driver BMP
>>  and has 1376 rows and 1376 columns
>>
>>> summary(image1)
>>  Object of class SpatialGridDataFrame
>>  Coordinates:
>>         min     max
>>  x    -2953 8123703
>>  y -8123703    2953
>>  Is projected: NA
>>  proj4string : [NA]
>>  Number of points: 2
>>  Grid attributes:
>>    cellcentre.offset cellsize cells.dim
>>  x                 0     5906      1376
>>  y          -8120750     5906      1376
>>  Data attributes:
>>     Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
>>   0.0000  1.0000  1.0000  0.9962  1.0000  1.0000
>>
>>> writeRAST6(image1, "image1", overwrite=TRUE)
>>  ATTENTION : Raster map <image1> already exists and will be overwritten
>>  Projection of input dataset and current location appear to match
>>
>>  RINGDA~1 terminé. Raster map <image1> created.
>>
>>> image1_2 <-  readRAST6(c("image1"), cat=c(TRUE), ignore.stderr=TRUE, plugin=NULL)
>>
>>> summary(image1_2)
>>  Object of class SpatialGridDataFrame
>>  Coordinates:
>>    min max
>>  x   0   1
>>  y   0   1
>>  Is projected: NA
>>  proj4string : [NA]
>>  Number of points: 2
>>  Grid attributes:
>>    cellcentre.offset cellsize cells.dim
>>  x               0.5        1         1
>>  y               0.5        1         1
>>  Data attributes:
>>
>>  1
>>
>>>
>> ------------------------------------------------------------------
>>
>> Thanks,
>>
>> Pierre
>>
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>> R-sig-Geo at r-project.org
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>>
>
>--
>Roger Bivand
>Economic Geography Section, Department of Economics, Norwegian School of
>Economics and Business Administration, Helleveien 30, N-5045 Bergen,
>Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
>e-mail: Roger.Bivand at nhh.no