convRad2Ref: Convert a band's scaled counts or radiance values to reflectance

Description

Convert a band's scaled counts to reflectance using a simple linear conversion without any kind of atmospheric correction etc.

Usage

# S4 method for Satellite
convRad2Ref(x, szen_correction = "TRUE")
# S4 method for RasterStack
convRad2Ref(x, mult, add, szen)
# S4 method for RasterLayer
convRad2Ref(x, mult, add, szen)

Value

If x is a Satellite object, a Satellite object with added converted layers;

if x is a raster::Raster* object, a raster::Raster* object with converted layer(s).

Arguments

x: An object of class Satellite, raster::RasterStack or raster::RasterLayer providing radiance values.
szen_correction: Logical; if TRUE, sun zenith correction is being applied.
mult: Multiplicative coefficient for value transformation (i.e. slope).
add: Additive coefficient for value transformation (i.e. offset)
szen: Cosine of solar zenith angle.

Details

The conversion functions are taken from USGS' Landsat 8 Data Users Handbook which is available online at https://www.usgs.gov/landsat-missions/landsat-8-data-users-handbook.

If the sensor does not provide linear conversion coefficients for reflectance computation, the reflectance is calculated using the solar irradiance following the functions taken from USGS' Landsat 7 manual, chapter 11.3.2, which is available online at https://www.usgs.gov/media/files/landsat-7-data-users-handbook.

Examples

Run this code

path <- system.file("extdata", package = "satellite")
files <- list.files(path, pattern = glob2rx("LC08*.TIF"), full.names = TRUE)
sat <- satellite(files)  
sat <- convRad2Ref(sat)

# If you use a raster layer, supply required meta information
bcde <- "B002n"
convRad2Ref(x = getSatDataLayer(sat, bcde),
            mult = getSatRADM(sat, bcde),
            add = getSatRADA(sat, bcde))