Sample Prague sky radiance at a chosen wavelength.

Evaluate the Prague spectral sky model at arbitrary spherical directions and return radiance at a user-specified wavelength. Use render_mode = "all" for atmosphere + solar disk, "atmosphere" for atmospheric radiance only, or "sun" for the solar disk only.

Usage

calculate_sky_radiance(
  phi,
  theta,
  lambda_nm,
  altitude = 0,
  elevation = 10,
  visibility = 50,
  albedo = 0.5,
  azimuth = 90,
  number_cores = 1,
  wide_spectrum = FALSE,
  render_mode = "all"
)

Arguments

phi

Azimuthal angle of the sample, degrees. Vectorized. Range 0 to 360.

theta

Vertical angle of the sample, degrees. Vectorized. Range -90 to 90.

lambda_nm

Wavelength in nanometers. Vectorized. Must lie within the loaded Prague dataset range.

altitude

Default 0, vectorized. Altitude of the viewer in meters. Range 0 to 15000.

elevation

Default 10, vectorized. Solar elevation angle above/below the horizon (degrees). Range -4.2 to 90.

visibility

Default 50, vectorized. Range 20 to 131.8. Meteorological range in kilometers for Prague model.

albedo

Default 0.5, vectorized. Range 0 to 1. Ground albedo.

azimuth

Default 90, single value. Solar azimuth (degrees). Defaults South.

number_cores

Default 1. Number of threads to use in computation.

wide_spectrum

Default FALSE. Whether to use the wide-spectrum (55-channel, polarised) coefficients.

render_mode

Default "all". One of "all", "atmosphere", or "sun". Use "all" for atmosphere + solar disk, "atmosphere" for atmospheric radiance only, or "sun" for the solar disk only.

Value

Numeric vector of radiance values at the requested wavelength(s).

Examples

if(run_documentation()) {
lambda_vals = calculate_sky_radiance(
  phi = c(90, 90),
  theta = c(45, 45),
  lambda_nm = 550,
  altitude = c(0, 10000),
  elevation = 20,
  visibility = 80,
  albedo = 0.1
)
cbind(altitude = c(0, 10000), radiance = lambda_vals)
}
#>  Coefficient file for this setting not yet present: this is a large file (2.4GB), download? [y/n] 
#> Error in check_coef_file("SkyModelDataset.dat"): Input not recognized.