Empty outputs with python GDAL

Question

Hello im new to Gdal and im struggling a with my codes. Everything seems to go well in my code mut the output bands at the end is empty. The no data value is set to 256 when i specify 255, so I don't really know whats wrong. Thanks any help will be appreciated!!!

Here is my code

from osgeo import gdal
from osgeo import gdalconst
from osgeo import osr
from osgeo import ogr
import numpy

#graticule
src_ds = gdal.Open("E:\\NFI_photo_plot\\photoplotdownloadAllCanada\\provincial_merge\\Aggregate\\graticule1.tif")
band = src_ds.GetRasterBand(1)
band.SetNoDataValue(0)
graticule = band.ReadAsArray()
print('graticule done')
band="none"

#Biomass
dataset1 = gdal.Open("E:\\NFI_photo_plot\\photoplotdownloadAllCanada\provincial_merge\\Aggregate\\Biomass_NFI.tif")
band1 = dataset1.GetRasterBand(1)
band1.SetNoDataValue(-1)
Biomass = band1.ReadAsArray()
maskbiomass = numpy.greater(Biomass, -1).astype(int)
print("biomass done")
Biomass="none"
band1="none"
dataset1="none"

#Baseline
dataset2 = gdal.Open("E:\\NFI_photo_plot\\Baseline\\TOTBM_250.tif")
band2 = dataset2.GetRasterBand(1)
band2.SetNoDataValue(0)
baseline = band2.ReadAsArray()
maskbaseline = numpy.greater(baseline, 0).astype(int)
print('baseline done')
baseline="none"
band2="none"
dataset2="none"

#sommation
biosource=(graticule+maskbiomass+maskbaseline)
biosource1=numpy.uint8(biosource)
biosource="none"

#Écriture
dst_file="E:\\NFI_photo_plot\\photoplotdownloadAllCanada\\provincial_merge\\Aggregate\\Biosource.tif"
dst_driver = gdal.GetDriverByName('GTiff')
dst_ds = dst_driver.Create(dst_file, src_ds.RasterXSize,
src_ds.RasterYSize, 1, gdal.GDT_Byte)

#projection
dst_ds.SetProjection( src_ds.GetProjection() )
dst_ds.SetGeoTransform( src_ds.GetGeoTransform() )
outband=dst_ds.GetRasterBand(1)
outband.WriteArray(biosource1,0,0)
outband.SetNoDataValue(255)
biosource="none"
graticule="none"

score 1 · Answer 1 · edited Jul 18 '22 at 17:05

A few pointers:

Where you have ="none", these need to be = None to close/cleanup the objects, otherwise you are setting the objects to an array of characters: n o n e, which is not what you intend to do.
Why do you have band1.SetNoDataValue(-1), while other NoData values are 0? Is this data source signed or unsigned? If unsigned, then -1 doesn't exist.
When you open rasters with gdal.Open without the access option, it defaults to gdal.GA_ReadOnly, which means your subsequent SetNoDataValue calls do nothing. If you want to modify the dataset, you need to use gdal.GA_Update as your second parameter to gdal.Open.
Another strategy to create a new raster is to use driver.CreateCopy; see the tutorial for details.

Empty outputs with python GDAL

1 Answers1