Compute the NDVI from spectral reflectance according to waveband definitions from standards or corresponding to satellite imagers.
NDVI(spct, imager = "LandsatOLI", wb.trim = FALSE)A numeric vector. When the wavelength range of spct does not
fully overlap with both wavebands NA is silently returned.
reflectance_spct or reflectance_mspct object.
character Name of the imager or standard to be used.
logical Flag telling if wavebands crossing spectral data boundaries are trimmed or ignored.
NDVI is used in remote sensing to the diagnose the condition of vegetation, including crops. It is used for Landsat imagery but also at the farm or plot scale using cameras on drones. It is computed as:
NDVI = (NIR - Red) / (NIR + Red)
The waveband ranges used to compute reflectance vary. Even the imagers
in the different Landsat satellites 1 to 8 have had somehow different
wavelength sensitivities. The NDVI() function uses the waveband
constructors Red and NIR defined in this
package. Reflectance is averaged over the wavebands using function
reflectance.