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Integrate skylight model. Work in progress.

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castano 2012-05-22 18:47:38 +00:00
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extern/skylight/ArHosekSkyModel.c vendored Normal file
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/*
This source is published under the following 3-clause BSD license.
Copyright (c) 2012, Lukas Hosek and Alexander Wilkie
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* None of the names of the contributors may be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/* ============================================================================
This file is part of a sample implementation of the analytical skylight model
presented in the SIGGRAPH 2012 paper
"An Analytic Model for Full Spectral Sky-Dome Radiance"
by
Lukas Hosek and Alexander Wilkie
Charles University in Prague, Czech Republic
Version: 1.0, May 11th, 2012
Please visit http://cgg.mff.cuni.cz/projects/SkylightModelling/ to check if
an updated version of this code has been published!
============================================================================ */
/*
All instructions on how to use this code are to be found in the accompanying
header file.
*/
#include "ArHosekSkyModel.h"
#include "ArHosekSkyModelData.h"
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
// Some macro definitions that occur elsewhere in ART, and that have to be
// replicated to make this a stand-alone module.
#ifndef NIL
#define NIL 0
#endif
#ifndef MATH_PI
#define MATH_PI 3.141593
#endif
#ifndef ALLOC
#define ALLOC(_struct) ((_struct *)malloc(sizeof(_struct)))
#endif
// internal definitions
typedef double *ArHosekSkyModel_Dataset;
typedef double *ArHosekSkyModel_Radiance_Dataset;
// internal functions
void ArHosekSkyModel_CookConfiguration(
ArHosekSkyModel_Dataset dataset,
ArHosekSkyModelConfiguration config,
double turbidity,
double albedo,
double solar_elevation
)
{
double * elev_matrix;
int int_turbidity = turbidity;
double turbidity_rem = turbidity - (double)int_turbidity;
solar_elevation = pow(solar_elevation / (MATH_PI / 2.0), (1.0 / 3.0));
// alb 0 low turb
elev_matrix = dataset + ( 9 * 6 * (int_turbidity-1) );
for( unsigned int i = 0; i < 9; ++i )
{
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
config[i] =
(1.0-albedo) * (1.0 - turbidity_rem)
* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
pow(solar_elevation, 5.0) * elev_matrix[i+45]);
}
// alb 1 low turb
elev_matrix = dataset + (9*6*10 + 9*6*(int_turbidity-1));
for(unsigned int i = 0; i < 9; ++i)
{
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
config[i] +=
(albedo) * (1.0 - turbidity_rem)
* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
pow(solar_elevation, 5.0) * elev_matrix[i+45]);
}
if(int_turbidity == 10)
return;
// alb 0 high turb
elev_matrix = dataset + (9*6*(int_turbidity));
for(unsigned int i = 0; i < 9; ++i)
{
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
config[i] +=
(1.0-albedo) * (turbidity_rem)
* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
pow(solar_elevation, 5.0) * elev_matrix[i+45]);
}
// alb 1 high turb
elev_matrix = dataset + (9*6*10 + 9*6*(int_turbidity));
for(unsigned int i = 0; i < 9; ++i)
{
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
config[i] +=
(albedo) * (turbidity_rem)
* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
pow(solar_elevation, 5.0) * elev_matrix[i+45]);
}
}
double ArHosekSkyModel_CookRadianceConfiguration(
ArHosekSkyModel_Radiance_Dataset dataset,
double turbidity,
double albedo,
double solar_elevation
)
{
double* elev_matrix;
int int_turbidity = turbidity;
double turbidity_rem = turbidity - (double)int_turbidity;
double res;
solar_elevation = pow(solar_elevation / (M_PI / 2.0), (1.0 / 3.0));
// alb 0 low turb
elev_matrix = dataset + (6*(int_turbidity-1));
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
res = (1.0-albedo) * (1.0 - turbidity_rem) *
( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
pow(solar_elevation, 5.0) * elev_matrix[5]);
// alb 1 low turb
elev_matrix = dataset + (6*10 + 6*(int_turbidity-1));
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
res += (albedo) * (1.0 - turbidity_rem) *
( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
pow(solar_elevation, 5.0) * elev_matrix[5]);
if(int_turbidity == 10)
return res;
// alb 0 high turb
elev_matrix = dataset + (6*(int_turbidity));
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
res += (1.0-albedo) * (turbidity_rem) *
( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
pow(solar_elevation, 5.0) * elev_matrix[5]);
// alb 1 high turb
elev_matrix = dataset + (6*10 + 6*(int_turbidity));
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
res += (albedo) * (turbidity_rem) *
( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
pow(solar_elevation, 5.0) * elev_matrix[5]);
return res;
}
double ArHosekSkyModel_GetRadianceInternal(
ArHosekSkyModelConfiguration configuration,
double theta,
double gamma
)
{
const double expM = exp(configuration[4] * gamma);
const double rayM = cos(gamma)*cos(gamma);
const double mieM = (1.0 + cos(gamma)*cos(gamma)) / pow((1.0 + configuration[8]*configuration[8] - 2.0*configuration[8]*cos(gamma)), 1.5);
const double zenith = sqrt(cos(theta));
return (1.0 + configuration[0] * exp(configuration[1] / (cos(theta) + 0.01))) *
(configuration[2] + configuration[3] * expM + configuration[5] * rayM + configuration[6] * mieM + configuration[7] * zenith);
}
// spectral version
ArHosekSkyModelState * arhosekskymodelstate_alloc_init(
const double turbidity,
const double albedo,
const double elevation
)
{
ArHosekSkyModelState * state = ALLOC(ArHosekSkyModelState);
for( unsigned int wl = 0; wl < 11; ++wl )
{
ArHosekSkyModel_CookConfiguration(
datasets[wl],
state->configs[wl],
turbidity,
albedo,
elevation
);
state->radiances[wl] =
ArHosekSkyModel_CookRadianceConfiguration(
datasetsRad[wl],
turbidity,
albedo,
elevation
);
}
return state;
}
void arhosekskymodelstate_free(
ArHosekSkyModelState * state
)
{
free(state);
}
double arhosekskymodel_radiance(
ArHosekSkyModelState * state,
double theta,
double gamma,
double wavelength
)
{
int low_wl = (wavelength - 320.0 ) / 40.0;
double interp = fmod((wavelength - 320.0 ) / 40.0, 1.0);
double val_low =
ArHosekSkyModel_GetRadianceInternal(
state->configs[low_wl],
theta,
gamma
)
* state->radiances[low_wl];
if(interp < 1e-6)
return val_low;
double result =
(1.0 - interp)
* val_low
+ interp
* ArHosekSkyModel_GetRadianceInternal(
state->configs[low_wl+1],
theta,
gamma
)
* state->radiances[low_wl+1];
return result;
}
// xyz version
ArHosekXYZSkyModelState * arhosek_xyz_skymodelstate_alloc_init(
const double turbidity,
const double albedo,
const double elevation
)
{
ArHosekXYZSkyModelState * state = ALLOC(ArHosekXYZSkyModelState);
for( unsigned int channel = 0; channel < 3; ++channel )
{
ArHosekSkyModel_CookConfiguration(
datasetsXYZ[channel],
state->configs[channel],
turbidity,
albedo,
elevation
);
state->radiances[channel] =
ArHosekSkyModel_CookRadianceConfiguration(
datasetsXYZRad[channel],
turbidity,
albedo,
elevation
);
}
return state;
}
void arhosek_xyz_skymodelstate_free(
ArHosekXYZSkyModelState * state
)
{
free(state);
}
double arhosek_xyz_skymodel_radiance(
ArHosekXYZSkyModelState * state,
double theta,
double gamma,
int channel
)
{
return
ArHosekSkyModel_GetRadianceInternal(
state->configs[channel],
theta,
gamma
)
* state->radiances[channel];
}

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/*
This source is published under the following 3-clause BSD license.
Copyright (c) 2012, Lukas Hosek and Alexander Wilkie
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* None of the names of the contributors may be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/* ============================================================================
This file is part of a sample implementation of the analytical skylight model
presented in the SIGGRAPH 2012 paper
"An Analytic Model for Full Spectral Sky-Dome Radiance"
by
Lukas Hosek and Alexander Wilkie
Charles University in Prague, Czech Republic
Version: 1.0, May 11th, 2012
Please visit http://cgg.mff.cuni.cz/projects/SkylightModelling/ to check if
an updated version of this code has been published!
============================================================================ */
/*
This code is taken from ART, a rendering research system written in a
mix of C99 / Objective C. Since ART is not a small system and is intended to
be inter-operable with other libraries, and since C does not have namespaces,
the structures and functions in ART all have to have the somewhat wordy
canonical names that begin with Ar.../ar..., like those seen in this example.
Usage information:
==================
Model initialisation
--------------------
A separate ArHosekSkyModelState has to be maintained for each spectral
band you want to use the model for. So in a renderer with num_channels
bands, you would need something like
ArHosekSkyModelState * skymodel_state[num_channels];
You then have to allocate these states. In the following code snippet, we
assume that "albedo" is defined as
double albedo[num_channels];
with a ground albedo value between [0,1] for each channel. The solar elevation
is given in radians.
for ( unsigned int i = 0; i < num_channels; i++ )
skymodel_state[i] =
arhosekskymodelstate_alloc_init(
turbidity,
albedo[i],
solarElevation
);
Using the model to generate skydome samples
-------------------------------------------
Generating a skydome radiance spectrum "skydome_result" for a given location
on the skydome determined via the angles theta and gamma works as follows:
double skydome_result[num_channels];
for ( unsigned int i = 0; i < num_channels; i++ )
skydome_result[i] =
arhosekskymodel_radiance(
skymodel_state[i],
theta,
gamma,
channel_center[i]
);
The variable "channel_center" is assumed to hold the channel center wavelengths
for each of the num_channels samples of the spectrum we are building.
Cleanup after use
-----------------
After rendering is complete, the content of the sky model states should be
disposed of via
for ( unsigned int i = 0; i < num_channels; i++ )
arhosekskymodelstate_free( skymodel_state[i] );
CIE XYZ Version of the Model
----------------------------
Usage of the CIE XYZ version of the model is exactly the same, except that
num_channels is of course always 3, and that ArHosekXYZSkyModelState and
arhosek_xyz_skymodel_radiance() have to be used instead of their spectral
counterparts.
*/
typedef double ArHosekSkyModelConfiguration[9];
// Spectral version of the model
typedef struct ArHosekSkyModelState
{
ArHosekSkyModelConfiguration configs[11];
double radiances[11];
}
ArHosekSkyModelState;
ArHosekSkyModelState * arhosekskymodelstate_alloc_init(
const double turbidity,
const double albedo,
const double elevation
);
void arhosekskymodelstate_free(
ArHosekSkyModelState * state
);
double arhosekskymodel_radiance(
ArHosekSkyModelState * state,
double theta,
double gamma,
double wavelength
);
// CIE XYZ version
typedef struct ArHosekXYZSkyModelState
{
ArHosekSkyModelConfiguration configs[3];
double radiances[3];
}
ArHosekXYZSkyModelState;
ArHosekXYZSkyModelState * arhosek_xyz_skymodelstate_alloc_init(
const double turbidity,
const double albedo,
const double elevation
);
void arhosek_xyz_skymodelstate_free(
ArHosekXYZSkyModelState * state
);
double arhosek_xyz_skymodel_radiance(
ArHosekXYZSkyModelState * state,
double theta,
double gamma,
int channel
);

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The files in this archive are a sample implementation of the analytical
skylight model presented in the SIGGRAPH 2012 paper
"An Analytic Model for Full Spectral Sky-Dome Radiance"
by
Lukas Hosek and Alexander Wilkie
Charles University in Prague, Czech Republic
Version: 1.0, May 11th, 2012
Please visit http://cgg.mff.cuni.cz/projects/SkylightModelling/ to check if
an updated version of this code has been published!
This archive contains the following files:
README.txt This file.
ArHosekSkyModel.h Header file for the reference functions. Their
usage is explained there, and sample code for
calling them is given.
ArHosekSkyModel.c Implementation of the functions.
ArHosekSkyModelData.h Coefficient data.
Please note that the source files are in C99, so that when e.g. compiling this
code with gcc, you have to add the "-std=c99" or "-std=gnu99" flags.

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@ -814,3 +814,52 @@ void CubeSurface::toGamma(float gamma)
}
}
#if 0
// @@ Provide solar azimuth.
#include "ArHoseSkyModel.h"
void CubeSurface::sky(float turbidity, float albedo[3], float solarElevation) {
ArHosekSkyModelState * skymodel_state[3];
for (int i = 0; i < num_channels; i++) {
skymodel_state[i] = arhosekskymodelstate_alloc_init(turbidity, albedo[i], solarElevation);
}
// 700 nm (red), 546.1 nm (green) and 435.8 nm (blue).
float channel_center[3] = {
700, // Red 620–740,
546.1, // Green 520–570,
435.8, // Blue 450–490,
};
// @@ For each pixel:
// What's the channel center for the RGB model?
double skydome_result[3];
for (unsigned int i = 0; i < num_channels; i++) {
skydome_result[i] = arhosekskymodel_radiance(skymodel_state[i], theta, gamma, channel_center[i]);
}
for (int i = 0; i < num_channels; i++) {
arhosek_skymodelstate_free(skymodel_state[i]);
}
/*
ArHosekXYZSkyModelState * skymodel_state[3];
for (int i = 0; i < num_channels; i++) {
skymodel_state[i] = arhosek_xyz_skymodelstate_alloc_init(turbidity, albedo[i], solarElevation);
}
// @@ For each pixel.
double skydome_result[3];
for (unsigned int i = 0; i < num_channels; i++) {
skydome_result[i] = arhosek_xyz_skymodel_radiance(skymodel_state[i], theta, gamma, i);
}
for (int i = 0; i < num_channels; i++) {
arhosek_xyz_skymodelstate_free(skymodel_state[i]);
}
*/
}
#endif