[STATSGRASS] import DTM with readRAST6()

Matteo Dall'Amico matteo.dallamico at ing.unitn.it
Mon Jul 9 09:26:22 EDT 2007


Hello everybody,
I am a new R & Grass user.
I am interested in doing a kriging of the Temperature in a basin,  
based on pixel elevation (DTM).
I use Grass 6.2.1 and R 2.5.1 and have installed the spgrass6 package.

The DTM is called "DTM_trentino_100m" and has a header and data like  
the following:

north:5158000.0
south:5058500.0
east:1729700.0
west:1611600.0
rows:995
cols:1181
-9999.0 -9999.0 -9999.0 370.84381103515625 372.55120849609375  
373.13128662109375 .....

I have opened R inside the Grass location, and imported the DTM:

 >  trentino.grid<-readRAST6("DTM_trentino_100m")
Creating BIL support files ...
Header File = /Users/Matteo/Documents/DataGrass/GBovest/ 
Permafrost/.tmp/nilo.local/DTM_trentino_100m.hdr
World File = /Users/Matteo/Documents/DataGrass/GBovest/ 
Permafrost/.tmp/nilo.local/DTM_trentino_100m.wld
Exporting Raster as double values(bytes=8)
Using the Current Region settings ...
north=5158000.000000
south=5058500.000000
east=1729700.000000
west=1611600.000000
r=995
c=1181

Percent complete:  100%
r.out.bin complete.

 > summary(trentino.grid)
Object of class SpatialGridDataFrame
Coordinates:
               min     max
coords.x1 1611600 1729700
coords.x2 5058500 5158000
Is projected: TRUE
proj4string :
[+proj=tmerc +lat_0=0.0000000000 +lon_0=9.0000000000 +k_0=0.9996000000
+x_0=1500000.0000000000 +y_0=0.0000000000 +a=6378388 +rf=297 +no_defs
+towgs84=-225.000,-65.000,9.000]
Number of points: 2
Grid attributes:
   cellcentre.offset cellsize cells.dim
1           1611650      100      1181
2           5058550      100       995
Data attributes:
DTM_trentino_100m
Min.   :1.192e-319
1st Qu.:1.065e-314
Median :1.066e-314
Mean   :1.285e-312
3rd Qu.:2.722e-312
Max.   :4.774e-312

As you can see, the import has been fully done, yet the attributes  
are not correct. In fact, the Min. value is 1.192e-319 and the Max is  
4.774e-312 but in reality the elevation changes between 60m to 3500m.
Have I done something wrong? What should I do?
Thank you in advance,

Matteo


---------------------------------
Matteo Dall'Amico
PhD candidate
CUDAM and department of Civil and Environmental Engineering
Universita' degli Studi di Trento
Via Mesiano 77 - 38050 Trento - Italy
email: matteo.dallamico at ing.unitn.it
Tel. +39 0461 882610
Fax +39 0461 882672
http://www.dottorato.it/trento/
---------------------------------


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