On Wed, 10 Feb 2010, Agustin Lobo wrote:
I think I tripped on this same stone, but cannot find anything in my
records, perhaps it's on the lost computer.
Sorry, can't find such a posting - maybe my search keys were wrong - you
could try the nabble archive.
The file test2.tif was made by plugin Interpolation in QGIS out of a
vector layer of points with nitrate concentration values, just
a simple inverse distance method. I think that the author f that
pluginis Marco Hugentobler (Marco, sorry if it's not you) to whom I'm
forwarding.
Relevant info from the metadata in QGIS for this raster:
Layer Spatial Reference System:
+proj=utm +zone=31 +ellps=intl +units=m +no_defs
Origin
424389,4.68549e+06
Pixel Size:
279.887,-279.887
No, it is 345.0078, 194.0195.
NW corner in QGIS (interactive):424388.820,4685490.931
SW corner in QGIS (interactive):424389.122,4635951.740
SW in R is 424389, 4635822
or SW cell centre 424561.5, 4635919.0 which is the SW corner plus 0.5* the
resolution.
Try:
GDALinfo(system.file("pictures/cea.tif", package = "rgdal")[1])
system(paste("gdalinfo", system.file("pictures/cea.tif", package =
?"rgdal")[1]))
to see the oddness of gdalinfo on your raster. The SW (LL) corner is north
of the NW (UL) one. The provided raster is OK, so I guess one might think
that yours isn't?
How is the plugin writing the GTiff?
Roger
Agus
2010/2/10 Roger Bivand <Roger.Bivand at nhh.no>
On Wed, 10 Feb 2010, Agustin Lobo wrote:
r3 <- readGDAL("test2.tif")
test2.tif has GDAL driver GTiff
and has 256 rows and 256 columns
image(r3,col=rainbow(128))
Collected from:
http://sites.google.com/site/eospansite/dummy
Yes, it is flipped on the Y axis. What software made it? Could you please
show the images with axes, as I think that the GTiff has a wrong sign on its
y-step? What are the coordinates of the NW and SW corners of the image in
QGIS? GDAL expects images to be read by row N to S, so a y-step with the
wrong sign (+ instead of -) flips the image northward.
Roger
PS:
gdalinfo externally has lower left north of upper left:
system("gdalinfo test2.tif")
Driver: GTiff/GeoTIFF
Files: test2.tif
Size is 256, 256
Coordinate System is:
PROJCS["ED50 / UTM zone 31N",
? ?GEOGCS["ED50",
? ? ? ?DATUM["European_Datum_1950",
? ? ? ? ? ?SPHEROID["International 1924",6378388,297.0000000000014,
? ? ? ? ? ? ? ?AUTHORITY["EPSG","7022"]],
? ? ? ? ? ?AUTHORITY["EPSG","6230"]],
? ? ? ?PRIMEM["Greenwich",0],
? ? ? ?UNIT["degree",0.0174532925199433],
? ? ? ?AUTHORITY["EPSG","4230"]],
? ?PROJECTION["Transverse_Mercator"],
? ?PARAMETER["latitude_of_origin",0],
? ?PARAMETER["central_meridian",3],
? ?PARAMETER["scale_factor",0.9996],
? ?PARAMETER["false_easting",500000],
? ?PARAMETER["false_northing",0],
? ?UNIT["metre",1,
? ? ? ?AUTHORITY["EPSG","9001"]],
? ?AUTHORITY["EPSG","23031"]]
Origin = (424389.000000000000000,4635822.000000000000000)
Pixel Size = (345.007812500000000,194.019531250000000)
Metadata:
?AREA_OR_POINT=Area
Image Structure Metadata:
?INTERLEAVE=BAND
Corner Coordinates:
Upper Left ?( ?424389.000, 4635822.000) ( ?2d 5'20.10"E, 41d52'11.88"N)
Lower Left ?( ?424389.000, 4685491.000) ( ?2d 4'56.97"E, 42d19'2.06"N)
Upper Right ( ?512711.000, 4635822.000) ( ?3d 9'11.42"E, 41d52'24.52"N)
Lower Right ( ?512711.000, 4685491.000) ( ?3d 9'15.31"E, 42d19'14.90"N)
Center ? ? ?( ?468550.000, 4660656.500) ( ?2d37'10.89"E, 42d 5'47.83"N)
Band 1 Block=256x4 Type=Float64, ColorInterp=Gray
and:
rows ? ? ? ?256
columns ? ? 256
bands ? ? ? 1
origin.x ? ? ? ?424389
origin.y ? ? ? ?4636016
res.x ? ? ? 345.0078
res.y ? ? ? 194.0195
oblique.x ? 0
oblique.y ? 0
driver ? ? ?GTiff
projection ?+proj=utm +zone=31 +ellps=intl +units=m +no_defs
file ? ? ? ?test2.tif
apparent band summary:
? GDType ? ? ? ?Bmin ? ? ? Bmax
1 Float64 -4294967295 4294967295
Metadata:
AREA_OR_POINT=Area
Agus
? ? ? ?[[alternative HTML version deleted]]