simple.ratio.index: Simple ratio index

In hsdar: Manage, Analyse and Simulate Hyperspectral Data

Simple ratio index

Description

Calculate simple ratio index (sr) for a single given band combination or for all possible band combinations. Calculating sr is a frequently used method to standardize reflectance values and to find relationships between properties of the objects and their spectral data.

Usage

sr(x, b1, b2, recursive = FALSE, bywavelength = TRUE)

Arguments

x	List of class Speclib or of class Nri for print and as.matrix methods.
b1	Band 1 given as band number or wavelength.
b2	Band 2 given as band number or wavelength.
recursive	If TRUE indices for all possible band combinations are calculated. If FALSE, only a single sr for the given bands in b1 and b2 is calculated.
bywavelength	Flag to determine if b1 and b2 are band number (bywavelength = FALSE) or wavelength (bywavelength = TRUE) values.

Details

Function performs the following calculation:

nri_{B1,~B2}=\frac{R_{B1}}{R_{B2}};

with R being reflectance values at wavelength B1 and B2, respectively.

If recursive = TRUE, all possible band combinations are calculated.

Value

If recursive = FALSE, a data frame with index values is returned. Otherwise result is an object of class Nri. See glm.nri for applying a generalised linear model to an array of simple ratio indices.

Author(s)

Lukas Lehnert

See Also

nri, glm.nri, glm, Speclib, Nri

Examples

data(spectral_data)

## Calculate SR	of Jordan (1969) (R_{800}/R_{680})
sr_600_680 <- sr(spectral_data, b1=800, b2=680)

## Calculate all possible combinations for WorldView-2-8
spec_WV <- spectralResampling(spectral_data, "WorldView2-8",
                              response_function = FALSE)
sr_WV <- sr(spec_WV, recursive = TRUE)
sr_WV

hsdar documentation built on March 18, 2022, 6:35 p.m.