Sample a direction from the Prague model. — calculate_sky

Evaluate the Prague spectral sky model at arbitrary spherical directions without writing an image, returning radiance-only samples.

Usage

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

Arguments

phi: Horizontal angle of the sample, degrees. Vectorized. Range 0 to 360.
theta: Vertical angle of the sample, degrees. Vectorized. Range -90 to 90.
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

3-column RGB matrix.

Examples

# Generate a basic atmosphere with the Prague model
if(run_documentation()) {
value_grid = expand.grid(
  phi = seq(0,360,by=30),
  theta = seq(0,90,by=10),
  altitude = c(0,10000)
 )
vals = calculate_sky_values(
  phi = value_grid$phi,
  theta = value_grid$theta,
  altitude = value_grid$altitude,
  elevation = 45,
  visibility = 120,
  albedo = 0
 )
 cbind(value_grid, 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.