Python GDAL – Using Raster Calculator

gdalpythonraster-calculator

i am using an hyperspectral image with 158 bands. I want to calculate raster. i am using the following python script 

import gdal # Import GDAL library bindings
from osgeo.gdalnumeric import *
from osgeo.gdalconst import *
import pylab as plt
import numpy as np
import xlrd
# The file that we shall be using
# Needs to be on current directory
filename = ('C:/Users/KIFF/Desktop/These/data/Hyperion/10th_bandmathref')
outFile = ('C:/Users/KIFF/Desktop/These/data/Hyperion/Math')
XLS=('C:/Users/KIFF/Desktop/These/data/Coef/bcoef.xlsx')
wb = xlrd.open_workbook(XLS)
sheet = wb.sheet_by_index(0)
sheet.cell_value(0, 0)


g = gdal.Open(filename, GA_ReadOnly)

# g should now be a GDAL dataset, but if the file isn't found
# g will be none. Let's test this:
if g is None:
    print ("Problem opening file %s!" % filename)
else:
    print ("File %s opened fine" % filename )

#band_array = g.ReadAsArray()
#print(band_array)
print ("[ RASTER BAND COUNT ]: ", g.RasterCount)

for band in range( g.RasterCount ):
    print (band)
    band += 1
    outFile = ('C:/Users/KIFF/Desktop/These/data/Results/Temp/Math_1_sur_value'+str(band)+'.tiff')
    #print ("[ GETTING BAND ]: ", band )
    srcband = g.GetRasterBand(band)
    if srcband is None:
        continue
    data1 = BandReadAsArray(srcband).astype(np.float)
    print(data1)
   # for i in range(3,sheet.nrows):
    b=sheet.cell_value(band+2,1)
    #print(b)
    dataOut = (1/data1)
    driver = gdal.GetDriverByName("ENVI")
    dsOut = driver.Create(outFile, g.RasterXSize, g.RasterYSize, 1)
    CopyDatasetInfo(g,dsOut)
    bandOut=dsOut.GetRasterBand(1)
    BandWriteArray(bandOut, dataOut)

for the print(data1) i got only some "1", but the real values are some floats

0
[[1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 ...
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]]
1
[[1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 ...
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]
 [1. 1. 1. ... 1. 1. 1.]]
2

Pixel value 0,139200

Can you find the mistake?

Best Answer

Try setting the raster data type - such as gdal.GDT_Float32

dsOut = driver.Create(outFile, g.RasterXSize, g.RasterYSize, 1, gdal.GDT_Float32)
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