get_br: Get band ratios

In BIO-RSG/oceancolouR: Various Functions for Satellite and Data Analysis

Get band ratios

Description

Given a matrix of Rrs (remote sensing reflectances) with column names, and the blue and green wavebands to use, calculate the band ratios.

Usage

get_br(rrs, blues, green, use_443nm = FALSE)

Arguments

rrs	Numeric matrix where rows = records, columns = Rrs wavebands, with named columns ("Rrs_XXX", where XXX is a wavelength in nanometres). Names must match c(blues, green), i.e. same names, from shortest waveband to longest.
blues	Character vector of Rrs wavebands in the blue range (e.g. c("Rrs_443", Rrs_488")), matching column name(s) in rrs, maximum 3 options, arranged from shortest waveband to longest. Note that if use_443nm=FALSE, the 443nm waveband will be removed and another must be used in its place.
green	String, Rrs waveband in the green range (e.g. "Rrs_547"), matching a column name in rrs
use_443nm	Logical value, TRUE to make the 443nm band an option in the band ratio

Details

Slightly negative Rrs are allowed according to the rules used by NASA OBPG: The shortest blue band used in the model must be > -0.001, and if there are 2 possible blue bands used in the model, the one with the lowest value must be > -0.001.

Value

Named list of two vectors: rrs_ocx (the band ratio values), and ratio_used (strings indicating which "blue" waveband was used for each band ratio)

BIO-RSG/oceancolouR documentation built on Feb. 2, 2025, 2:01 a.m.