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Data Structures | Public Member Functions
PragueSkyModel Class Reference

#include <PragueSkyModel.h>

Data Structures

struct  AvailableData
 Structure with parameter ranges available in currently loaded dataset. More...
 
class  DatasetNotFoundException
 Exception thrown by the initialize method if the passed dataset file could not be found. More...
 
class  DatasetReadException
 Exception thrown by the initialize method if an error occurred while reading the passed dataset file. More...
 
class  NoPolarisationException
 
class  NotInitializedException
 Exception thrown when using the model without calling the initialize method first. More...
 
struct  Parameters
 Structure holding all parameters necessary for querying the model. More...
 
class  Vector3
 A simple 3D vector implementation. Provides some basic operations. More...
 

Public Member Functions

void initialize (const std::string &filename, const double singleVisibility=0.0)
 
bool isInitialized () const
 
AvailableData getAvailableData () const
 
Parameters computeParameters (const Vector3 &viewPoint, const Vector3 &viewDirection, const double groundLevelSolarElevationAtOrigin, const double groundLevelSolarAzimuthAtOrigin, const double visibility, const double albedo) const
 
double skyRadiance (const Parameters &params, const double wavelength) const
 
double sunRadiance (const Parameters &params, const double wavelength) const
 
double polarisation (const Parameters &params, const double wavelength) const
 
double transmittance (const Parameters &params, const double wavelength, const double distance) const
 

Detailed Description

Implementation of the physically-based sky model presented by Wilkie et al. [2021] (https://cgg.mff.cuni.cz/publications/skymodel-2021/) and Vevoda et al. [2022]. Improves on previous work especially in accuracy of sunset scenarios. Based on reconstruction of radiance from a small dataset fitted to a large set of images obtained by brute force atmosphere simulation.

Provides evaluation of spectral sky radiance, sun radiance, transmittance and polarisation for observer at a specific altitude above ground. The range of configurations depends on supplied dataset. The full version models atmosphere of visibility (meteorological range) from 20 km to 131.8 km for sun elevations from -4.2 degrees to 90 degrees, observer altitudes from 0 km to 15 km and ground albedo from 0 to 1, and provides results for wavelengths from 280 nm to 2480 nm.

Usage:

  1. Create PragueSkyModel object and call its initialize method with a path to the dataset file.
  2. The model is parametrized by several values that are gathered in PragueSkyModel::Parameters structure. You can either fill this structure manually (in that case see its description) or just call computeParameters, which will compute it for you based on a few basic parameters.
  3. Use the Parameters structure when calling skyRadiance, sunRadiance, transmittance, or polarisation methods to obtain the respective quantities.

Throws:

  • DatasetNotFoundException: if the specified dataset file could not be found
  • DatasetReadException: if an error occurred while reading the dataset file
  • NoPolarisationException: if the polarisation method is called but the model does not contain polarisation data
  • NotInitializedException: if the model is used without calling the initialize method first

Note: The entire model is written in a single class and does not depend on anything except of STL. It defines a simple Vector3 class to simplify working with points and directions and expects using this class when passing viewing point and direction to the computeParameters method.

Definition at line 58 of file PragueSkyModel.h.

Constructor & Destructor Documentation

◆ PragueSkyModel()

PragueSkyModel::PragueSkyModel ( )
inline

Definition at line 330 of file PragueSkyModel.h.

Member Function Documentation

◆ computeParameters()

PragueSkyModel::Parameters PragueSkyModel::computeParameters ( const Vector3 &  viewPoint,
const Vector3 &  viewDirection,
const double  groundLevelSolarElevationAtOrigin,
const double  groundLevelSolarAzimuthAtOrigin,
const double  visibility,
const double  albedo 
) const

Computes all the parameters in the Parameters structure necessary for querying the model.

Expects view point and direction, sun elevation and azimuth at origin, ground level visibility and ground albedo. Assumes origin at [0,0,0] with Z axis pointing up. Thus view point [0, 0, 100] defines observer altitude 100 m. Range of available values depends on the used dataset. The full version supports altitude from [0, 15000] m, elevation from [-0.073, PI/2] rad, azimuth from [0, PI] rad, visibility from [20, 131.8] km, and albedo from [0, 1]. Values outside range of the used dataset are clamped to the nearest supported value.

Definition at line 612 of file PragueSkyModel.cpp.

◆ getAvailableData()

PragueSkyModel::AvailableData PragueSkyModel::getAvailableData ( ) const

Gets parameter ranges available in currently loaded dataset.

Throws NotInitializedException if called without initializing the model first.

Definition at line 585 of file PragueSkyModel.cpp.

◆ initialize()

void PragueSkyModel::initialize ( const std::string &  filename,
const double  singleVisibility = 0.0 
)

Prepares the model and loads the given dataset file into memory.

If a positive visibility value is passed, only a portion of the dataset needed for evaluation of that particular visibility is loaded (two nearest visibilities are loaded if the value is included in the dataset or one nearest if not). Otherwise, the entire dataset is loaded.

Throws:

  • DatasetNotFoundException: if the specified dataset file could not be found
  • DatasetReadException: if an error occurred while reading the dataset file

Definition at line 571 of file PragueSkyModel.cpp.

◆ isInitialized()

bool PragueSkyModel::isInitialized ( ) const
inline

Definition at line 343 of file PragueSkyModel.h.

◆ polarisation()

double PragueSkyModel::polarisation ( const Parameters &  params,
const double  wavelength 
) const

Computes degree of polarisation for given parameters and wavelength (full dataset supports wavelengths from 280 nm to 2480 nm). Can be negative.

Throws:

  • NoPolarisationException: if the polarisation method is called but the model does not contain polarisation data
  • NotInitializedException: if called without initializing the model first

Definition at line 864 of file PragueSkyModel.cpp.

◆ skyRadiance()

double PragueSkyModel::skyRadiance ( const Parameters &  params,
const double  wavelength 
) const

Computes sky radiance only (without direct sun contribution) for given parameters and wavelength (full dataset supports wavelengths from 280 nm to 2480 nm).

Throws NotInitializedException if called without initializing the model first.

Definition at line 813 of file PragueSkyModel.cpp.

◆ sunRadiance()

double PragueSkyModel::sunRadiance ( const Parameters &  params,
const double  wavelength 
) const

Computes sun radiance only (without radiance inscattered from the sky) for given parameters and wavelength (full dataset supports wavelengths from 280 nm to 2480 nm).

Checks whether the parameters correspond to view direction hitting the sun and returns 0 if not.

Throws NotInitializedException if called without initializing the model first.

Definition at line 826 of file PragueSkyModel.cpp.

◆ transmittance()

double PragueSkyModel::transmittance ( const Parameters &  params,
const double  wavelength,
const double  distance 
) const

Computes transmittance between view point and a point certain distance away from it along view direction.

Expects the Parameters structure, wavelength (full dataset supports wavelengths from 280 nm to 2480 nm) and the distance (any positive number, use std::numeric_limits<double>::max() for infinity).

Throws NotInitializedException if called without initializing the model first.

Definition at line 1049 of file PragueSkyModel.cpp.

The documentation for this class was generated from the following files: