SkyModel¶

class SkyModel¶

Bases: TypedReferenceCount

A planet’s air as three media (Hillaire 2020, after Bruneton & Neyret 2008), and its CPU light model: Rayleigh-scattering molecules and Mie-scattering aerosols, each thinning exponentially with height, and an ozone layer that only absorbs (a tent profile). Units are the shaders’: kilometres and 1/km. The defaults are the Earth of Hillaire’s paper.

transmittance() is the colour of the sunlight (or moonlight) after it crossed the air to a point, for a DirectionalLight; sky_irradiance() a rough irradiance of a horizontal surface by the sky (single scattering over a spread of directions, plus 40 % for the higher orders), for an AmbientLight. The native twin of acron.sky’s Atmosphere, computed in double precision; a default sky_irradiance takes some 50 us.

Inheritance diagram

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SkyModel.__init__()¶

The Earth’s air (Hillaire 2020).

Any air: radii and scale heights in km, coefficients in 1/km.

SkyModel.extinction()¶: The extinction (1/km, rgb) at a height (km above the ground).

static SkyModel.get_class_type()¶

SkyModel.get_ground_albedo()¶

SkyModel.get_ground_radius()¶

SkyModel.get_mie_absorption()¶

SkyModel.get_mie_g()¶

SkyModel.get_mie_scale_height()¶

SkyModel.get_mie_scattering()¶

SkyModel.get_ozone_absorption()¶

SkyModel.get_ozone_centre()¶

SkyModel.get_ozone_width()¶

SkyModel.get_rayleigh_scale_height()¶

SkyModel.get_rayleigh_scattering()¶

SkyModel.get_top_radius()¶

SkyModel.ray_to_top()¶: The distance (km) from height_km along cos_zenith to the top of the air, or -1 when the ray meets the ground first.

SkyModel.set_ground_albedo()¶

SkyModel.set_ground_radius()¶

SkyModel.set_mie_absorption()¶

SkyModel.set_mie_g()¶

SkyModel.set_mie_scale_height()¶

SkyModel.set_mie_scattering()¶

SkyModel.set_ozone_absorption()¶

SkyModel.set_ozone_centre()¶

SkyModel.set_ozone_width()¶

SkyModel.set_rayleigh_scale_height()¶

SkyModel.set_rayleigh_scattering()¶

SkyModel.set_top_radius()¶

SkyModel.sky_irradiance()¶

A rough irradiance (rgb) the sky gives a horizontal surface at height_km under a sun in the direction sun_up (z up) of the given illuminance: single scattering summed over directions upward directions (a golden spiral, uniform in solid angle) of steps samples each (the sunlight to each sample a 12-step transmittance), times 1.4 for the higher orders.

sky_irradiance() for a white sun of this illuminance.

SkyModel.transmittance()¶: How much light (rgb, 0..1) gets from the top of the air down to a point height_km up, arriving from cos_zenith (1: straight down from overhead); zero when the planet is in the way. steps steps crowded round the ray’s lowest point (optical_depth_d()).

SkyModel.with_weather()¶: This air with haze times the aerosols (1: clear) and humidity 0..1 (wet aerosols scatter more and absorb less: hazier, whiter); haze_height >= 0 overrides the aerosols’ scale height.