eradiate.scenes.atmosphere.HomogeneousAtmosphere

class eradiate.scenes.atmosphere.HomogeneousAtmosphere(id='atmosphere', geometry=None, bottom=<Quantity(0.0, 'kilometer')>, top=<Quantity(10.0, 'kilometer')>, sigma_s=_Nothing.NOTHING, sigma_a=0.0, phase=_Nothing.NOTHING)

Bases: eradiate.scenes.atmosphere._core.Atmosphere

Homogeneous atmosphere scene element [homogeneous].

This class builds an atmosphere consisting of a homogeneous medium with customisable collision coefficients and phase function, attached to a cuboid shape.

Parameters

• id (str, optional, default: "atmosphere") – User-defined object identifier.

• geometry (AtmosphereGeometry or dict or str, optional, default: None) – Parameters defining the basic geometry of the atmosphere.

• bottom (quantity or float, default: 0 km) – Atmosphere’s bottom altitude.

  Unit-enabled field (default: ucc[length])

• top (quantity or float, default: 10 km.) – Atmosphere’s top altitude.

  Unit-enabled field (default: ucc[length]).

• sigma_s (Spectrum or float, default: AirScatteringCoefficientSpectrum()) – Atmosphere scattering coefficient value.

  Can be initialised with a dictionary processed by spectrum_factory.

• sigma_a (Spectrum, default: 0.0 ucc[collision_coefficient]) – Atmosphere absorption coefficient value. Defaults disable absorption.

  Can be initialised with a dictionary processed by spectrum_factory.

• phase (PhaseFunction, default: RayleighPhaseFunction()) – Scattering phase function.

  Can be initialised with a dictionary processed by phase_function_factory.

Fields

• id (str or None) – User-defined object identifier.

• geometry (AtmosphereGeometry or None) – Parameters defining the basic geometry of the atmosphere.

• sigma_s (Spectrum or float) – Atmosphere scattering coefficient value.

• sigma_a (Spectrum) – Atmosphere absorption coefficient value.

• phase (PhaseFunction) – Scattering phase function.

eval_albedo(spectral_ctx)

Return albedo.

Parameters

spectral_ctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode).

Returns

quantity – Albedo.

eval_mfp(ctx)

Compute a typical scattering mean free path. This rough estimate can be used e.g. to compute a distance guaranteeing that the medium can be considered optically thick.

Parameters

ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.

Returns

mfp (quantity) – Mean free path estimate.

eval_shape(ctx)

Return the shape enclosing the atmosphere’s volume.

Parameters

ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.

Returns

shape (CuboidShape or SphereShape) – Computed shape used as the medium stencil for kernel dictionary generation.

eval_sigma_a(spectral_ctx)

Return absorption coefficient.

Parameters

spectral_ctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode).

Returns

quantity – Absorption coefficient.

eval_sigma_s(spectral_ctx)

Return scattering coefficient.

Parameters

spectral_ctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode).

Returns

quantity – Scattering coefficient.

eval_sigma_t(spectral_ctx)

Return extinction coefficient.

Parameters

spectral_ctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode).

Returns

quantity – Extinction coefficient.

kernel_dict(ctx)

Return a dictionary suitable for kernel scene configuration.

Parameters

ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.

Returns

KernelDict – Kernel dictionary which can be loaded as a Mitsuba object.

kernel_media(ctx)

Return medium plugin specifications only.

Parameters

ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.

Returns

kernel_dict (KernelDict) – A kernel dictionary containing all the media attached to the atmosphere.

kernel_phase(ctx)

Return phase function plugin specifications only.

Parameters

ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.

Returns

kernel_dict (KernelDict) – A kernel dictionary containing all the phase functions attached to the atmosphere.

kernel_shapes(ctx)

Return shape plugin specifications only.

Parameters

ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.

Returns

kernel_dict (KernelDict) – A kernel dictionary containing all the shapes attached to the atmosphere.

kernel_width_plane_parallel(ctx)

When using a plane parallel geometry, compute the size of the cuboid shape enclosing the participating medium representing the atmosphere.

Parameters

ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.

Returns

width (quantity) – Computed cuboid width, eval to 10 / self.eval_mfp(ctx) if ` self.geometry.width` is set to AUTO, self.geometry.width otherwise.

Raises

ValueError – When a geometry other than PlaneParallelGeometry is used.

property bottom

Atmosphere bottom altitude.

Type

pint.Quantity

property height

Atmosphere height.

Type

pint.Quantity

property id_medium

Kernel dictionary key of the atmosphere’s medium object.

Type

str

property id_phase

Kernel dictionary key of the atmosphere’s phase function object.

Type

str

property id_shape

Kernel dictionary key of the atmosphere’s shape object.

Type

str

property top

Atmosphere top altitude.

Type

pint.Quantity