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HDR: Add remaining aerosol types

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Now the properties of the atmospheric medium can be changed through the
property tree.
This commit is contained in:
Fernando García Liñán 2023-04-16 07:17:49 +02:00
parent b0cfcd4a62
commit 82d415cbd4
8 changed files with 269 additions and 56 deletions
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36
Effects/HDR/atmos-aerial-perspective.eff
View file

@ -1,6 +1,21 @@
<?xml version="1.0" encoding="utf-8"?>
<PropertyList>
<name>Effects/HDR/atmos-aerial-perspective</name>
<parameters>
<!-- atmos.glsl -->
<aerosol-type>
<use>/sim/rendering/hdr/atmos/aerosol-type</use>
</aerosol-type>
<aerosol-turbidity>
<use>/sim/rendering/hdr/atmos/aerosol-turbidity</use>
</aerosol-turbidity>
<ground-albedo>
<use>/sim/rendering/hdr/atmos/ground-albedo</use>
</ground-albedo>
<month-of-the-year>
<use>/sim/time/utc/month</use>
</month-of-the-year>
</parameters>
<technique n="1">
<pass>
<program>
@ -16,6 +31,27 @@
<type>sampler-2d</type>
<value type="int">0</value>
</uniform>
<!-- atmos.glsl -->
<uniform>
<name>aerosol_type</name>
<type>int</type>
<value><use>aerosol-type</use></value>
</uniform>
<uniform>
<name>aerosol_turbidity</name>
<type>float</type>
<value><use>aerosol-turbidity</use></value>
</uniform>
<uniform>
<name>ground_albedo</name>
<type>float</type>
<value><use>ground-albedo</use></value>
</uniform>
<uniform>
<name>month_of_the_year</name>
<type>int</type>
<value><use>month-of-the-year</use></value>
</uniform>
</pass>
</technique>
</PropertyList>

36
Effects/HDR/atmos-sky-view.eff
View file

@ -1,6 +1,21 @@
<?xml version="1.0" encoding="utf-8"?>
<PropertyList>
<name>Effects/HDR/atmos-sky-view</name>
<parameters>
<!-- atmos.glsl -->
<aerosol-type>
<use>/sim/rendering/hdr/atmos/aerosol-type</use>
</aerosol-type>
<aerosol-turbidity>
<use>/sim/rendering/hdr/atmos/aerosol-turbidity</use>
</aerosol-turbidity>
<ground-albedo>
<use>/sim/rendering/hdr/atmos/ground-albedo</use>
</ground-albedo>
<month-of-the-year>
<use>/sim/time/utc/month</use>
</month-of-the-year>
</parameters>
<technique n="1">
<pass>
<program>
@ -14,6 +29,27 @@
<type>sampler-2d</type>
<value type="int">0</value>
</uniform>
<!-- atmos.glsl -->
<uniform>
<name>aerosol_type</name>
<type>int</type>
<value><use>aerosol-type</use></value>
</uniform>
<uniform>
<name>aerosol_turbidity</name>
<type>float</type>
<value><use>aerosol-turbidity</use></value>
</uniform>
<uniform>
<name>ground_albedo</name>
<type>float</type>
<value><use>ground-albedo</use></value>
</uniform>
<uniform>
<name>month_of_the_year</name>
<type>int</type>
<value><use>month-of-the-year</use></value>
</uniform>
</pass>
</technique>
</PropertyList>

36
Effects/HDR/atmos-transmittance.eff
View file

@ -1,6 +1,21 @@
<?xml version="1.0" encoding="utf-8"?>
<PropertyList>
<name>Effects/HDR/atmos-transmittance</name>
<parameters>
<!-- atmos.glsl -->
<aerosol-type>
<use>/sim/rendering/hdr/atmos/aerosol-type</use>
</aerosol-type>
<aerosol-turbidity>
<use>/sim/rendering/hdr/atmos/aerosol-turbidity</use>
</aerosol-turbidity>
<ground-albedo>
<use>/sim/rendering/hdr/atmos/ground-albedo</use>
</ground-albedo>
<month-of-the-year>
<use>/sim/time/utc/month</use>
</month-of-the-year>
</parameters>
<technique n="1">
<pass>
<program>
@ -9,6 +24,27 @@
<fragment-shader>Shaders/HDR/math.glsl</fragment-shader>
<fragment-shader>Shaders/HDR/atmos.glsl</fragment-shader>
</program>
<!-- atmos.glsl -->
<uniform>
<name>aerosol_type</name>
<type>int</type>
<value><use>aerosol-type</use></value>
</uniform>
<uniform>
<name>aerosol_turbidity</name>
<type>float</type>
<value><use>aerosol-turbidity</use></value>
</uniform>
<uniform>
<name>ground_albedo</name>
<type>float</type>
<value><use>ground-albedo</use></value>
</uniform>
<uniform>
<name>month_of_the_year</name>
<type>int</type>
<value><use>month-of-the-year</use></value>
</uniform>
</pass>
</technique>
</PropertyList>

4
Shaders/HDR/aerial_perspective.glsl
View file

@ -8,9 +8,9 @@ uniform float fg_CameraDistanceToEarthCenter;
uniform float fg_SunZenithCosTheta;
uniform float fg_EarthRadius;
const float AP_SLICE_COUNT = 16.0;
const float AP_SLICE_COUNT = 32.0;
const float AP_MAX_DEPTH = 128000.0;
const float AP_SLICE_WIDTH_PIXELS = 64.0;
const float AP_SLICE_WIDTH_PIXELS = 32.0;
const float AP_SLICE_SIZE = 1.0 / AP_SLICE_COUNT;
const float AP_TEXEL_WIDTH = 1.0 / (AP_SLICE_COUNT * AP_SLICE_WIDTH_PIXELS);

180
Shaders/HDR/atmos.glsl
View file

@ -1,23 +1,29 @@
#version 330 core
// math.glsl
float M_PI();
float M_1_PI();
float M_1_4PI();
uniform int aerosol_type;
uniform float aerosol_turbidity;
uniform float ground_albedo;
uniform int month_of_the_year;
uniform float fg_EarthRadius;
const float RAYLEIGH_PHASE_SCALE = 0.05968310365946075091; // 3/(16*pi)
const float HENYEY_ASYMMETRY = 0.8;
const float HENYEY_ASYMMETRY2 = HENYEY_ASYMMETRY*HENYEY_ASYMMETRY;
// Rayleigh scattering coefficient at sea level, units m^-1
// "Rayleigh-scattering calculations for the terrestrial atmosphere"
// by Anthony Bucholtz (1995).
/*
* Rayleigh scattering coefficient at sea level, units m^-1
* "Rayleigh-scattering calculations for the terrestrial atmosphere"
* by Anthony Bucholtz (1995).
*/
const vec4 molecular_scattering_coefficient_base =
vec4(6.605e-6, 1.067e-5, 1.842e-5, 3.156e-5);
// Ozone absorption cross section, units m^2 / molecules
// "High spectral resolution ozone absorption cross-sections"
// by V. Gorshelev et al. (2014).
/*
* Ozone absorption cross section, units m^2 / molecules
* "High spectral resolution ozone absorption cross-sections"
* by V. Gorshelev et al. (2014).
*/
const vec4 ozone_cross_section =
vec4(3.472e-21, 3.914e-21, 1.349e-21, 11.03e-23) * 1e-4f;
@ -45,34 +51,12 @@ const float ozone_height_distribution[] = float[](
0.0
);
/*
* Every aerosol type expects 5 parameters:
* - Scattering cross section
* - Absorption cross section
* - Base density (km^-3)
* - Background density (km^-3)
* - Height scaling parameter
* These parameters can be sent as uniforms.
*
* This model for aerosols and their corresponding parameters come from
* "A Physically-Based Spatio-Temporal Sky Model"
* by Guimera et al. (2018).
*/
// Urban
uniform vec4 aerosol_absorption_cross_section =
vec4(2.8722e-24, 4.6168e-24, 7.9706e-24, 1.3578e-23);
uniform vec4 aerosol_scattering_cross_section =
vec4(1.5908e-22, 1.7711e-22, 2.0942e-22, 2.4033e-22);
uniform float aerosol_base_density = 1.3681e20;
uniform float aerosol_relative_background_density = 2e6 / 1.3681e20;
uniform float aerosol_height_scale = 0.73;
uniform float aerosol_turbidity = 1.0;
uniform int month_of_the_year = 0;
uniform vec4 ground_albedo = vec4(0.3);
uniform float fg_EarthRadius;
// math.glsl
float M_PI();
float M_2PI();
float M_1_PI();
float M_1_4PI();
float sqr(float x);
//------------------------------------------------------------------------------
@ -141,7 +125,7 @@ vec4 get_multiple_scattering(sampler2D transmittance_lut,
{
// Solid angle subtended by the planet from a point at d distance
// from the planet center.
float omega = 2.0 * M_PI() * (1.0 - sqrt(d*d - get_earth_radius()*fg_EarthRadius) / d);
float omega = M_2PI() * (1.0 - sqrt(sqr(d) - sqr(get_earth_radius())) / d);
omega = max(0.0, omega);
vec4 T_to_ground = transmittance_from_lut(transmittance_lut, cos_theta, 0.0);
@ -179,7 +163,7 @@ vec4 get_molecular_absorption_coefficient(float h)
{
int i = int(clamp(h / 9.0, 0.0, 6.0));
float density = ozone_height_distribution[i] *
ozone_mean_monthly_dobson[month_of_the_year] * 2.6867e20f; // molecules / m^2
ozone_mean_monthly_dobson[month_of_the_year-1] * 2.6867e20f; // molecules / m^2
density /= 9e3; // m^-3
return ozone_cross_section * density; // m^-1
}
@ -187,10 +171,111 @@ vec4 get_molecular_absorption_coefficient(float h)
/*
* Return the aerosol density for a given altitude in kilometers.
*/
float get_aerosol_density(float h)
float get_aerosol_density(float h, float base_density, float height_scale,
float relative_background_density)
{
return aerosol_base_density * (exp(-h / aerosol_height_scale)
+ aerosol_relative_background_density);
if (aerosol_type == 0) {
// Only for the Background aerosol type, no dependency on height
return base_density * (1.0 + relative_background_density);
} else {
return base_density * (exp(-h / height_scale) + relative_background_density);
}
}
/*
* Get the aerosol collision coefficients for a given altitude h in km.
* The two main parameters are the aerosol type (0 to 8), and the turbidity.
* Every aerosol type expects 5 parameters:
* - Scattering cross section
* - Absorption cross section
* - Base density (km^-3)
* - Background density (km^-3)
* - Height scaling parameter
*
* This model for aerosols and their corresponding parameters come from
* "A Physically-Based Spatio-Temporal Sky Model"
* by Guimera et al. (2018).
*/
void get_aerosol_collision_coefficients(in float h,
out vec4 absorption,
out vec4 scattering)
{
vec4 aerosol_absorption_cross_section, aerosol_scattering_cross_section;
float aerosol_base_density, aerosol_background_density, aerosol_height_scale;
if (aerosol_type == 0) {
// Background
aerosol_absorption_cross_section = vec4(4.5517e-19, 5.9269e-19, 6.9143e-19, 8.5228e-19);
aerosol_scattering_cross_section = vec4(1.8921e-26, 1.6951e-26, 1.7436e-26, 2.1158e-26);
aerosol_base_density = 2.584e17;
aerosol_background_density = 2e6;
} else if (aerosol_type == 1) {
// Desert-Dust
aerosol_absorption_cross_section = vec4(4.6758e-16, 4.4654e-16, 4.1989e-16, 4.1493e-16);
aerosol_scattering_cross_section = vec4(2.9144e-16, 3.1463e-16, 3.3902e-16, 3.4298e-16);
aerosol_base_density = 1.8662e18;
aerosol_background_density = 2e6;
aerosol_height_scale = 2.0;
} else if (aerosol_type == 2) {
// Maritime Clean
aerosol_absorption_cross_section = vec4(6.3312e-19, 7.5567e-19, 9.2627e-19, 1.0391e-18);
aerosol_scattering_cross_section = vec4(4.6539e-26, 2.721e-26, 4.1104e-26, 5.6249e-26);
aerosol_base_density = 2.0266e17;
aerosol_background_density = 2e6;
aerosol_height_scale = 0.9;
} else if (aerosol_type == 3) {
// Maritime Mineral
aerosol_absorption_cross_section = vec4(6.9365e-19, 7.5951e-19, 8.2423e-19, 8.9101e-19);
aerosol_scattering_cross_section = vec4(2.3699e-19, 2.2439e-19, 2.2126e-19, 2.021e-19);
aerosol_base_density = 2.0266e17;
aerosol_background_density = 2e6;
aerosol_height_scale = 2.0;
} else if (aerosol_type == 4) {
// Polar Antarctic
aerosol_absorption_cross_section = vec4(1.3399e-16, 1.3178e-16, 1.2909e-16, 1.3006e-16);
aerosol_scattering_cross_section = vec4(1.5506e-19, 1.809e-19, 2.3069e-19, 2.5804e-19);
aerosol_base_density = 2.3864e16;
aerosol_background_density = 2e6;
aerosol_height_scale = 30.0;
} else if (aerosol_type == 5) {
// Polar Arctic
aerosol_absorption_cross_section = vec4(1.0364e-16, 1.0609e-16, 1.0193e-16, 1.0092e-16);
aerosol_scattering_cross_section = vec4(2.1609e-17, 2.2759e-17, 2.5089e-17, 2.6323e-17);
aerosol_base_density = 2.3864e16;
aerosol_background_density = 2e6;
aerosol_height_scale = 30.0;
} else if (aerosol_type == 6) {
// Remote Continental
aerosol_absorption_cross_section = vec4(4.5307e-18, 5.0662e-18, 4.4877e-18, 3.7917e-18);
aerosol_scattering_cross_section = vec4(1.8764e-18, 1.746e-18, 1.6902e-18, 1.479e-18);
aerosol_base_density = 6.103e18;
aerosol_background_density = 2e6;
aerosol_height_scale = 0.73;
} else if (aerosol_type == 7) {
// Rural
aerosol_absorption_cross_section = vec4(5.0393e-23, 8.0765e-23, 1.3823e-22, 2.3383e-22);
aerosol_scattering_cross_section = vec4(2.6004e-22, 2.4844e-22, 2.8362e-22, 2.7494e-22);
aerosol_base_density = 8.544e18;
aerosol_background_density = 2e6;
aerosol_height_scale = 0.73;
} else if (aerosol_type == 8) {
// Urban
aerosol_absorption_cross_section = vec4(2.8722e-24, 4.6168e-24, 7.9706e-24, 1.3578e-23);
aerosol_scattering_cross_section = vec4(1.5908e-22, 1.7711e-22, 2.0942e-22, 2.4033e-22);
aerosol_base_density = 1.3681e20;
aerosol_background_density = 2e6;
aerosol_height_scale = 0.73;
}
float aerosol_relative_background_density =
aerosol_background_density / aerosol_base_density;
float aerosol_density = get_aerosol_density(
h, aerosol_base_density, aerosol_height_scale,
aerosol_relative_background_density);
aerosol_density *= aerosol_turbidity * 1e-3;
absorption = aerosol_absorption_cross_section * aerosol_density;
scattering = aerosol_scattering_cross_section * aerosol_density;
}
/*
@ -204,12 +289,11 @@ void get_atmosphere_collision_coefficients(in float h,
out vec4 molecular_scattering,
out vec4 extinction)
{
h *= 1e-3; // To km
h = max(h, 0.0); // In case height is negative
float aerosol_density = get_aerosol_density(h * 1e-3) * aerosol_turbidity;
aerosol_absorption = aerosol_absorption_cross_section * aerosol_density * 1e-3;
aerosol_scattering = aerosol_scattering_cross_section * aerosol_density * 1e-3;
molecular_absorption = get_molecular_absorption_coefficient(h * 1e-3);
molecular_scattering = get_molecular_scattering_coefficient(h * 1e-3);
get_aerosol_collision_coefficients(h, aerosol_absorption, aerosol_scattering);
molecular_absorption = get_molecular_absorption_coefficient(h);
molecular_scattering = get_molecular_scattering_coefficient(h);
extinction =
aerosol_absorption + aerosol_scattering +
molecular_absorption + molecular_scattering;

22
Shaders/HDR/atmos_aerial_perspective.frag
View file

@ -21,14 +21,17 @@ uniform mat4 fg_ViewMatrixInverse;
uniform vec3 fg_CameraPositionCart;
uniform vec3 fg_SunDirectionWorld;
const float AP_SLICE_COUNT = 16.0;
const float AP_SLICE_COUNT = 32.0;
const float AP_MAX_DEPTH = 128000.0;
const int AERIAL_PERSPECTIVE_STEPS = 10;
const float RADIUS_OFFSET = 10.0;
// pos_from_depth.glsl
vec3 get_view_space_from_depth(vec2 uv, float depth);
// atmos.glsl
float get_earth_radius();
float get_ray_end(vec3 ray_origin, vec3 ray_dir, float t_max);
vec4 compute_inscattering(in vec3 ray_origin,
in vec3 ray_dir,
in float t_max,
@ -55,10 +58,23 @@ void main()
vec3 frag_pos = get_view_space_from_depth(coord, 1.0);
vec3 ray_dir = vec4(fg_ViewMatrixInverse * vec4(normalize(frag_pos), 0.0)).xyz;
vec3 ray_origin = fg_CameraPositionCart;
vec3 ray_end = ray_origin + ray_dir * depth;
float t_max = depth;
if (length(ray_end) <= (get_earth_radius() + RADIUS_OFFSET)) {
ray_end = normalize(ray_end) * (get_earth_radius() + RADIUS_OFFSET + 1.0);
ray_dir = ray_end - ray_origin;
t_max = length(ray_dir);
ray_dir /= t_max;
}
vec4 transmittance;
vec4 L = compute_inscattering(fg_CameraPositionCart,
vec4 L = compute_inscattering(ray_origin,
ray_dir,
depth,
t_max,
fg_SunDirectionWorld,
AERIAL_PERSPECTIVE_STEPS,
transmittance_lut,

6
Shaders/HDR/skydome.frag
View file

@ -48,10 +48,10 @@ vec4 get_sun_darkening_factor(float cos_theta)
void main()
{
vec3 ray_dir = normalize(ray_dir);
float azimuth = atan(ray_dir.y, ray_dir.x) / M_PI() * 0.5 + 0.5;
vec3 frag_ray_dir = normalize(ray_dir);
float azimuth = atan(frag_ray_dir.y, frag_ray_dir.x) / M_PI() * 0.5 + 0.5;
// Undo the non-linear transformation from the sky-view LUT
float l = asin(ray_dir.z);
float l = asin(frag_ray_dir.z);
float elev = sqrt(abs(l) / (M_PI() * 0.5)) * sign(l) * 0.5 + 0.5;
vec4 sky_radiance = texture(sky_view_tex, vec2(azimuth, elev));

5
defaults.xml
View file

@ -535,6 +535,11 @@ Started September 2000 by David Megginson, david@megginson.com
<hdr>
<antialiasing-technique type="int" userarchive="y">2</antialiasing-technique>
<exposure-compensation type="float">0.0</exposure-compensation>
<atmos>
<aerosol-type type="int">8</aerosol-type>
<aerosol-turbidity type="float">1.0</aerosol-turbidity>
<ground-albedo type="float">0.4</ground-albedo>
</atmos>
<bloom>
<strength type="float">0.01</strength>
<filter-radius type="float">0.005</filter-radius>