eradiate.scenes.measure.MultiDistantMeasure¶

class eradiate.scenes.measure.MultiDistantMeasure(id='measure', srf=NOTHING, sampler='independent', rfilter='box', spp=1000, target=None, ray_offset=None, *, direction_layout=NOTHING)[source]¶

Bases: AbstractDistantMeasure

Multi-distant radiance measure scene element [mdistant, multi_distant].

This scene element creates a measure consisting of an array of radiancemeters positioned at an infinite distance from the scene. In practice, it can be used to compute the radiance leaving a scene at the top of the atmosphere (or canopy if there is no atmosphere). Coupled to appropriate post-processing operations, scene reflectance can be derived from the radiance values it produces.

Class method constructors

`aring`(zenith, azimuths, **kwargs)	Construct using an azimuth ring viewing direction layout.
`grid`(zeniths, azimuths, **kwargs)	Construct using a gridded viewing direction layout, defined as the Cartesian product of zenith and azimuth arrays.
`hplane`(zeniths, azimuth, **kwargs)	Construct using a hemisphere plane cut viewing direction layout.
`from_angles`(angles, **kwargs)	Construct using a direction layout defined by explicit (zenith, azimuth) pairs.
`from_directions`(directions, **kwargs)	Construct using a direction layout defined by explicit direction vectors.

Parameters:

id (str, optional, default: "measure") – Identifier of the current scene element.
srf (path-like or str or SpectralResponseFunction or dict, default: DeltaSRF(wavelengths=550.0 * ureg.nm)) – Spectral response function (SRF). If a path is passed, it attempts to load a dataset from that location. If a keyword is passed, e.g. 'sentinel_2a-msi-4', the corresponding dataset is looked up through the file resolver.
sampler ({"independent", "stratified", "multijitter", "orthogonal", "ldsampler"}, default: "independent") – Mitsuba sampler used to generate pseudo-random number sequences.
rfilter ({"box", "gaussian", "tent", "mitchell", "catmullrom", "lanczos"}, default: "box") – Reconstruction filter used to scatter samples on sensor pixels. By default, using a box filter is recommended.
spp (int, default: 1000) – Number of samples per pixel.
target (Target or dict or array-like, optional) – Target specification. The target can be specified using an array-like with 3 elements (which will be converted to a TargetPoint) or a dictionary interpreted by Target.convert(). If set to None (not recommended), the default target point selection method is used: rays will not target a particular region of the scene.
ray_offset (float or quantity, optional, default: None) – Manually control the distance between the target and ray origins. If unset, ray origins are positioned outside of the scene and this measure is rigorously distant.
direction_layout (dict or array-like or Layout, optional, default: DirectionLayout(directions=[0, 0, 1])) – A viewing direction layout. Specification through a dictionary or arrays, as documented by Layout.convert(), is also possible. The constructor methods provide a convenient interface to configure this parameter automatically.

Fields:

id (str or None) – Identifier of the current scene element.
srf (SpectralResponseFunction) – Spectral response function (SRF).
sampler (str) – Mitsuba sampler used to generate pseudo-random number sequences.
rfilter (str) – Reconstruction filter used to scatter samples on sensor pixels.
spp (int) – Number of samples per pixel.
target (Target or None) – Target specification.
ray_offset (quantity or None) – Manually control the distance between the target and ray origins.
direction_layout (Layout) – A viewing direction layout.

Notes

Setting the target parameter is required to get meaningful results. Experiment classes should take care of setting it appropriately.

classmethod aring(zenith, azimuths, **kwargs)[source]¶

Construct using an azimuth ring viewing direction layout.

Parameters:

zenith (float or quantity) – Azimuth ring zenith value. Unitless values are converted to ucc['angle'].
azimuths (array-like) – List of azimuth values. Unitless values are converted to ucc['angle'].
azimuth_convention (AzimuthConvention or str, optional) – The azimuth convention applying to the viewing direction layout. If unset, the global default convention is used.
**kwargs – Remaining keyword arguments are forwarded to the MultiDistantMeasure constructor.

Returns:

MultiDistantMeasure

classmethod from_angles(angles, **kwargs)[source]¶

Construct using a direction layout defined by explicit (zenith, azimuth) pairs.

Parameters:

angles (array-like) – A sequence of (zenith, azimuth), interpreted as (N, 2)-shaped array.
azimuth_convention (AzimuthConvention or str, optional) – The azimuth convention applying to the viewing direction layout. If unset, the global default convention is used.
**kwargs – Remaining keyword arguments are forwarded to the MultiDistantMeasure constructor.

Returns:

MultiDistantMeasure

classmethod from_directions(directions, **kwargs)[source]¶

Construct using a direction layout defined by explicit direction vectors.

Parameters:

directions (array-like) – A sequence of direction vectors, interpreted as (N, 3)-shaped array.
azimuth_convention (AzimuthConvention or str, optional) – The azimuth convention applying to the viewing direction layout. If unset, the global default convention is used.
**kwargs – Remaining keyword arguments are forwarded to the MultiDistantMeasure constructor.

Returns:

MultiDistantMeasure

Warning

Viewing directions are defined pointing outwards the target location.

classmethod grid(zeniths, azimuths, **kwargs)[source]¶

Construct using a gridded viewing direction layout, defined as the Cartesian product of zenith and azimuth arrays.

Parameters:

azimuths (array-like) – List of azimuth values.
zeniths (array-like) – List of zenith values.
azimuth_convention (AzimuthConvention or str, optional) – The azimuth convention applying to the viewing direction layout. If unset, the global default convention is used.
**kwargs – Remaining keyword arguments are forwarded to the MultiDistantMeasure constructor.

Returns:

MultiDistantMeasure

classmethod hplane(zeniths, azimuth, **kwargs)[source]¶

Construct using a hemisphere plane cut viewing direction layout.

Parameters:

zeniths (array-like) – List of zenith values. Negative values are mapped to the azimuth + 180° half-plane. Unitless values are converted to ucc['angle'].
azimuth (float or quantity) – Hemisphere plane cut azimuth value. Unitless values are converted to ucc['angle'].
azimuth_convention (AzimuthConvention or str, optional) – The azimuth convention applying to the viewing direction layout. If unset, the global default convention is used.
**kwargs – Remaining keyword arguments are forwarded to the MultiDistantMeasure constructor.

Returns:

MultiDistantMeasure

is_distant()¶: Return True iff measure records radiometric quantities at infinite distance.

traverse(callback)¶

Traverse this scene element and collect kernel dictionary template and parameter update map contributions.

Parameters:: callback (SceneTraversal) – Callback data structure storing the collected data.

update()¶: Enforce internal state consistency. This method should be called when fields are modified. It is automatically called as a post-init step.

property film_resolution¶

Getter for film resolution as a (int, int) pair.

Type:: tuple

property objects¶

Map of child objects associated with this scene element.

Returns:: dict – A dictionary mapping object names to a corresponding object to be inserted in the Eradiate scene graph.

property params¶

Returns:: dict[str, SceneParameter] or None – A dictionary mapping parameter paths, consisting of dot-separated strings, to a corresponding update protocol.