Calculate NDVI using Python

Question

Below is the NDVI equation,

NDVI = (NIR — VIS)/(NIR + VIS)

With the help of python, I'm trying to calculate the NDVI equation.

I've tried this:

inRaster = ('Landsat.tif')

out_NDVI_file = ('NDVI.tif')

red = arcpy.Describe(inRaster+'/Band_3')

NIR = arcpy.Describe(inRaster+'/Band_4')

num = arcpy.sa.Float(NIR-red)

denom = arcpy.sa.Foat(NIR+red)

NDVI = arcpy.sa.Divide(num, denom)

NDVI.Save(out_NDVI_file)

But, I'm getting this error message,

Traceback (most recent call last):

  File "F:\abc\def.py", line 32, in <module>

    num = arcpy.sa.Float(NIR-red)

TypeError: unsupported operand type(s) for -: 'geoprocessing describe data object' and 'geoprocessing describe data object'

Can anyone tell me, where I'm going wrong?

Answer 1

Try replacing,

red = arcpy.Describe(inRaster+'/Band_3')

NIR = arcpy.Describe(inRaster+'/Band_4')

with

red = arcpy.sa.Raster(inRaster+'/Band_3')

NIR = arcpy.sa.Raster(inRaster+'/Band_4')

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