Extract Index¶

This function extracts an index from a hyperspectral datacube, which is a Spectral_data class instance created while reading in with readimage with mode='envi'. There is also a parameter to allow some flexibility on using wavelengths that are at least close to the wavelength bands require to calculate a specific index.

plantcv.hyperspectral.extract_index(array, index="NDVI", distance=20)

returns calculated index array (instance of the Spectral_data class)

• Parameters:

  • array - A hyperspectral datacube object, an instance of the Spectral_data class, (read in with pcv.readimage with mode='envi')
  • index - Desired index, either "ndvi" for normalized difference vegetation index, "gdvi" for green difference vegetation index, "savi" for soil adjusted vegetation index, "pri" for photochemical reflectance index, "aci" for anthocyanin content index, or "ari" for anthocyanin reflectance index.
  • distance - Amount of flexibility (in nanometers) regarding using wavelengths that are at least close to the wavelength bands require to calculate a specific index

• Note:

  • We are adding potential indices as needed by PlantCV contributors, however the functions added to PlantCV are shaped in large part by the end users so please post feature requests (including a specific index), questions, and comments on the GitHub issues page.
• Example use:
  • Below

from plantcv import plantcv as pcv

# Set global debug behavior to None (default), "print" (to file), 
# or "plot" (Jupyter Notebooks or X11)
pcv.params.debug = "print"

# Extract NDVI index from the datacube 
ndvi_array  = pcv.hyperspectral.extract_index(array=spectral_data, index="NDVI", distance=20)

ndvi_array  = pcv.hyperspectral.extract_index(array=spectral_data, index="GDVI")

ndvi_array  = pcv.hyperspectral.extract_index(array=spectral_data, index="SAVI")

ndvi_array  = pcv.hyperspectral.extract_index(array=spectral_data, index="ARI")

ndvi_array  = pcv.hyperspectral.extract_index(array=spectral_data, index="ACI")

NDVI array image

GDVI array image

SAVI array image

ARI array image

ACI array image

Source Code: Here