[gdal-dev] numpy array to raster

[Kyle Shannon]

Is 'myarray' full of zeros?

/**
 *
 * Kyle Shannon
 * ksshannon at gmail.com
 *
 */



On Tue, Jan 31, 2012 at 19:20, questions anon <questions.anon at gmail.com>wrote:

> thanks Frank, following your instructions with:
>
> src_ds=gdal_array.OpenArray(myarray)
> dst_ds =
> gdal.GetDriverByName('GTiff').Create('E:/test/rasterise/mynewraster.tif',ncols,
> nrows, 1 ,gdal.GDT_Byte)
>  dst_ds.SetGeoTransform(geotransform)
> dst_ds.GetRasterBand(1).WriteArray(myarray)
>
> I do not receive any error messages but the tiff produced are all just
> zeros. Is there a step I am missing?
> thanks
>
>
> On Wed, Feb 1, 2012 at 12:07 PM, Frank Warmerdam <warmerdam at pobox.com>wrote:
>
>> On Tue, Jan 31, 2012 at 4:38 PM, questions anon
>> <questions.anon at gmail.com> wrote:
>> > I need to output my numpy array as a raster so that someone else can
>> access
>> > the data in ArcGIS. So basically the steps I need are:
>> > read numpy array into gdal
>> > convert to raster
>> > use latitude and longitude and array size to set projection
>> >
>> > I am really struggling with gdal because I can't seem to find enough
>> > documentation about each step to understand what it is doing.
>> > Here are some of the steps I think I need:
>> >
>> > myarray=myarray
>> > #the extent and shape of my array
>> > xmin,ymin,xmax,ymax=[139.8,-39.2,150.0,-33.6]
>> > ncols,nrows=[193,106]
>> > xres=(xmax-xmin)/float(ncols)
>> > yres=(ymax-ymin)/float(nrows)
>> > geotransform=(xmin,xres,0,ymax,0, -yres)
>> >
>> > from osgeo import gdal
>> > from osgeo import gdal_array
>> >
>> > src_ds=gdal_array.OpenArray(myarray)
>> >
>> > dst_ds =
>> >
>> gdal.GetDriverByName('GTiff').Create('E:/test/rasterise/mynewraster.tif',ncols,
>> > nrows, 1 ,gdal.GDT_Byte)
>> > dst_rb = dst_ds.GetRasterBand(0)
>> > dst_ds.SetGeoTransform(geotransform)
>> > output = gdal.RasterizeLayer(dst_ds)
>>
>> Dear "Questions Anon",
>>
>> There are a variety of Python related information at:
>>
>>  http://trac.osgeo.org/gdal/wiki/GdalOgrInPython
>>
>> One serious issue with the above is that "gdal.RasterizeLayer()" is used
>> to
>> turn vector data into raster data - for instance to rasterize polygon
>> features
>> into an existing raster file.  I think you want to write your array into a
>> raster file.  I think you can just call "dst_ds.WriteArray(myarray)".
>>
>> Alternatively if that method does not exist on the dataset, you
>> can write the one band like:
>>
>>  dst_ds.GetRasterBand(1).WriteArray(myarray)
>>
>> Some of the samples referenced from the GdalOgrInPython should be
>> helpful though I understand it can be hard to know where to look.
>>
>> Best regards,
>> --
>>
>> ---------------------------------------+--------------------------------------
>> I set the clouds in motion - turn up   | Frank Warmerdam,
>> warmerdam at pobox.com
>> light and sound - activate the windows | http://pobox.com/~warmerdam
>> and watch the world go round - Rush    | Geospatial Software Developer
>>
>
>
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