Oz, NODATA_VALUES is supposed to be a pixel value (integer or real) whereas "null" is a string. Try to convert all the "null" strings into an unused pixel value like -9999 in raster1.asc
Regards, -- Chaitanya kumar CH. On Fri, Feb 27, 2009 at 2:34 AM, Oz Nahum <[email protected]> wrote: > Hi, > I have to ascii raster that I created using a text editor: > the first is called raster1.asc and looks like this: > ncols 6 > nrows 4 > xllcorner 3366820.0000019 > yllcorner 5814589.0300007 > cellsize 10 > NODATA_value -9999 > 1 1 1 1 1 1 > 1 1 1 1 1 1 > 1 1 1 1 1 1 > 1 1 1 1 -9999 -9999 > The second is called raster2.asc and looks like this: > ncols 6 > nrows 4 > xllcorner 3366820.0000019 > yllcorner 5814589.0300007 > cellsize 10 > NODATA_value null > 1 1 1 1 1 1 > 1 1 1 1 1 1 > 1 1 1 1 1 1 > 1 1 1 1 null null > > When I import them into python I find out the lower right corner of the > first raster is not giving the correct value: instead of 'null' qgis > displays the value '31081'. > The other raster is imported correctly and it showing 'null's for the two > last data cells. > >>>> dataset = gdal.Open('raster2.asc', GA_ReadOnly) >>>> b = gdal_array.DatasetReadAsArray(dataset) >>>> b > array([[1, 1, 1, 1, 1, 1], > [1, 1, 1, 1, 1, 1], > [1, 1, 1, 1, 1, 1], > [1, 1, 1, 1, 0, 0]], dtype=int16) >>>> dataset = gdal.Open('raster1.asc', GA_ReadOnly) >>>> a = gdal_array.DatasetReadAsArray(dataset) >>>> a > array([[ 1, 1, 1, 1, 1, 1], > [ 1, 1, 1, 1, 1, 1], > [ 1, 1, 1, 1, 1, 1], > [ 1, 1, 1, 1, -9999, 31081]], dtype=int16) >>>> > > > So before I go and open a bug, I just wanted to know - what is wrong ? Maybe > it's my system setup ? Maybe i don't write correct ascii rasters ? Also, > another thing I would like to bypass is the fact that 'null' values are > formed as zeros in gdal-numpy - this could lead to error when doing some > raster manipulations. Is there a way to by pass this (besides being > aware...)? > > I use Debian Lenny the latest relevant packages from. > > Thanks, > Oz N, > Grad Studend, > Universität Tübingen > > > > -- > > ---- > Imagine there's no countries > It isn't hard to do > Nothing to kill or die for > And no religion too > Imagine all the people > Living life in peace > ---- > You all must read 'The God Delusion' > http://en.wikipedia.org/wiki/The_God_Delusion > --- > when one person suffers from a delusion it is called insanity. When many > people suffer from a delusion it is called religion." > Robert Pirsig, Zen and the Art of Motorcycle Maintenance > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
