API Reference¶

This page lists the public Python API for LESS 3.0.5. User code starts with import less; every name below is available from the top-level less namespace. Tutorials explain complete workflows, while this page provides a searchable inventory of interfaces, result types, and related chapters.

Compute availability depends on the installed platform and native backends. Use less.can_use() or scene.can_use() before submitting a workflow. If an implementation is unavailable, LESS raises an explicit error and does not silently substitute an approximation.

Scenes, objects, and geometry¶

API	Purpose
`less.Scene`	Persistent scene that owns geometry, illumination, backend selection, and simulation lifecycle.
`less.InstanceHandle`	Updates position, rotation, and scale of placed instances.
`less.Object`	Scene object containing one or more geometry components.
`less.Terrain`	Flat, DEM, or mesh terrain.
`less.Geometry`	Base class for geometry components.
`less.Mesh`	Explicit triangle mesh.
`less.TurbidBoundary`	Closed boundary for statistical vegetation media.
`less.TurbidSampling`	Quality, budget, and seed configuration for resident Turbid leaf samples.
`less.BoundaryValidationReport`	Turbid boundary validation result.
`less.TurbidBoundaryError`	Raised for an invalid Turbid boundary.

Scene lifecycle and common operations¶

Scene.simulate(sensor_or_process, **kwargs)
Scene.build()
Scene.rebuild()
Scene.update_instances()

scene = less.Scene(backend="auto", device=0)
product = scene.simulate(sensor_or_process)

scene.build()                 # Optional preparation; reuses unchanged state
scene.rebuild()               # Force geometry reload and acceleration rebuild
scene.update_instances()      # Commit InstanceHandle transform changes

Common public methods:

Method	Description
`Scene.add(obj, positions=..., rotations=..., scales=...)`	Adds one or more instances and returns an `InstanceHandle`.
`Scene.get_object(name)`	Returns a named object.
`Scene.simulate(sensor_or_process, **kwargs)`	Builds when required, then executes a simulation or process.
`Scene.measure(measurement)`	Runs a non-radiative geometric measurement.
`Scene.solve_energy_balance(...)`	Solves scene energy balance.
`Scene.update_property(path, property)`	Updates the property of a selected scene element.
`Scene.apply_temperatures(product)` / `Scene.clear_temperatures()`	Applies or clears temperature state.
`Scene.validate_turbid_boundaries()`	Validates all Turbid boundaries.
`Scene.can_use(feature, explain=False)`	Checks whether the scene and backend can execute a feature.
`Scene.backend_info()`	Returns the selected backend and device information.
`Scene.inspect_recipe()`	After a successful simulation, returns JSON-safe workflow, component, cache, and native artifact identity for diagnostics.
`Scene.show(...)`	Opens the interactive scene viewer.
`Scene.save(path, pack=True)` / `Scene.load(path)`	Saves and loads a scene.

Common object and terrain methods include Object.add_component(), Object.set_property(), Object.get_property(), Terrain.set_property(), and Terrain.height_at().

Properties¶

API	Purpose
`less.Property`	Base property class.
`less.OpticalVegetation`	Base class for two-sided vegetation optics.
`less.Lambertian`	Lambertian reflectance.
`less.Prospect`	PROSPECT leaf optical model.
`less.Fluspect`	Leaf reflectance, transmittance, and fluorescence.
`less.RPV`	RPV non-Lambertian reflectance model.
`less.WaterSurface`	Wind-dependent directional reflection and an optional water-leaving term for optically deep water.
`less.CoxMunk`	Cox–Munk water-surface slope statistics from 10 m wind speed and direction.
`less.PrescribedRrs`	User-supplied, glint-removed above-water remote-sensing reflectance.
`less.DeepWaterIOP`	Deep-water water-leaving estimate from absorption and backscattering coefficients.
`less.SpectrumDB`	Property values from a spectral database.
`less.ThermalProperty`	Temperature and longwave emissivity.
`less.BiophysicalProperty`	Physiology and energy-balance parameters.
`less.Farquhar`	Farquhar photosynthesis and stomatal-conductance model.
`less.Microclimate`	Air temperature, humidity, wind, carbon dioxide, and related conditions.

Spatial texture inputs¶

Textures are spatial inputs to named Property parameters; they are not standalone properties. See Spatial textures and property fields for complete UV, GeoTIFF, RGB, thermal, and serialization examples.

API	Purpose
`less.Texture`	Abstract base type for public texture declarations.
`less.ScalarTexture`	One scalar value per pixel, including temperature in K.
`less.SpectralTexture`	Measured values on an explicit or metadata wavelength grid.
`less.RGBTexture`	RGB input with explicit empirical spectral reconstruction.
`less.WorldXY`	Georeferenced world-X/Y mapping and outside-raster policy.
`Property.with_field(name, texture)`	Attaches one texture while retaining the Property's constant fallback.
`Property.with_fields(**textures)`	Attaches multiple named texture parameters.

Common texture controls are mapping, filter, wrap, nodata, missing_uv, outside_spectral_domain, raster_bands, scale, and offset. ScalarTexture and SpectralTexture also accept class_values={class_code: physical_value} for categorical rasters such as land cover. Scene-level resident-data controls are Scene.texture_memory_budget_bytes and Scene.texture_tile_size.

Microwave-domain properties are less.MicrowaveSoil, less.MicrowaveVegetation, less.MicrowaveTrunk, less.MicrowaveDisc, less.MicrowaveCylinder, less.MicrowaveLeaf, less.MicrowaveNeedle, and less.MicrowaveBranch. Check capability status before using a specialized domain workflow.

Illumination and atmosphere¶

API	Purpose
`less.Illumination`	Combines a top-of-atmosphere source with an atmosphere model.
`less.Sun`	Solar direction and TOA beam-normal spectral irradiance.
`less.NoAtmosphere`	Vacuum boundary: unattenuated direct beam and no diffuse sky.
`less.PrescribedAtmosphere`	User-specified direct-beam and diffuse-horizontal transmittance.
`less.SimpleSpectralAtmosphere`	Fast simplified spectral atmosphere.
`less.HosekWilkieAtmosphere`	Directional Hosek–Wilkie sky.
`less.SixSAtmosphere`	Optional 6S atmosphere.
`less.Atmosphere`	Built-in layered atmosphere and surface-to-sensor transport.
`less.CloudLayer`	1-D thermal cloud slab with independent-pixel cover mixing.
`less.AtmosphericProfile`	Layered atmospheric profile.
`less.AtmosphereDatabase`	Built-in atmosphere, aerosol, and spectral database.
`less.AtmosphereResult`	Atmospheric solver result.
`less.LibRadtranRunner`	Optional libRadtran runner.
`less.LibRadtranUnavailableError`	Raised when libRadtran is unavailable.

See Atmosphere and Surface–Atmosphere Transport for model parameters and units.

Projections, sensors, and instruments¶

Projections¶

API	Purpose
`less.Orthographic`	Orthographic projection.
`less.Perspective`	Perspective projection.
`less.Fisheye`	Fisheye projection.
`less.Pushbroom`	Satellite or airborne pushbroom projection.

Imaging and non-imaging sensors¶

API	Product
`less.OpticalImager`	`less.ImageProduct`
`less.ThermalImager`	`less.ImageProduct`
`less.SIFImager`	`less.ImageProduct`
`less.BRFSensor`	`less.BRFProduct`
`less.RadiationFieldSensor`	`less.RadiationFieldProduct`
`less.IrradianceMapSensor`	`less.IrradianceMapProduct`
`less.MicrowaveRadiometer`	Microwave radiometry product; check capability first.
`less.RadarScatterometer`	Radar scattering product; check capability first.
`less.Instrument`	Instrument and multi-band response configuration.

Processes and measurements¶

API	Purpose
`less.RadiationFieldProcess`	Computes scene radiation state.
`less.EnergyBalanceProcess`	Jointly solves sunlit/shaded temperatures and energy fluxes.
`less.PhotosynthesisProcess`	Solves photosynthesis and stomatal conductance.
`less.SIFProcess`	Solves solar-induced chlorophyll fluorescence.
`less.Measurement`	Base class for non-radiative measurements.
`less.LAIMeasurement`	Computes leaf area index.
`less.CHMMeasurement`	Produces a canopy height model.

Related results and errors include less.EnergyBalanceResult, less.ComponentEnergyBalanceResult, less.JointThermoPhysiologySummary, less.ConvergenceError, and less.SolveResult.

LiDAR¶

API	Purpose
`less.Scanner`	Scanner configuration.
`less.Platform`	Base platform class.
`less.Aircraft`, `less.UAV`	Airborne platforms.
`less.Tripod`, `less.Vehicle`	Terrestrial platforms.
`less.Waypoint`, `less.ScanPosition`	Flight waypoints and scan positions.
`less.LiDARSurvey`	Combines a platform, scanner, and acquisition plan.
`less.PointCloud`	LiDAR point-cloud product.

Spectral configuration and satellite bands¶

API	Purpose
`less.SpectralBands`	Base spectral-band collection.
`less.DiscreteBands`	Arbitrary non-uniform discrete bands.
`less.Hyperspectral`	Uniform hyperspectral sampling.
`less.SRFBands`	Bands with spectral response functions.
`less.gaussian_bands`	Gaussian SRFs from centre wavelength and FWHM.
`less.Sentinel2A`	Sentinel-2A bands and SRFs.
`less.Landsat8_OLI`	Landsat 8 OLI bands and SRFs.
`less.SpectralProfile`, `less.SpectralBand`	Spectral response descriptions.

Products¶

Products carry scientific arrays and actual native execution metadata. Use each product's save() and show() methods for export and visualization.

API	Purpose
`less.ImageProduct`	Optical, thermal, or SIF image.
`less.InstrumentImageProduct`	Image retaining instrument-band metadata.
`less.BRFProduct`	Multi-direction BRF.
`less.RadiationFieldProduct`	Three-dimensional radiation field.
`less.IrradianceMapProduct`	Upwelling and downwelling irradiance maps.
`less.EnergyBalanceProduct`	Temperatures and energy fluxes.
`less.RadiationFieldProcessProduct`	Radiation-process state.
`less.PhotosynthesisProcessProduct`	Photosynthetic rate and stomatal conductance.
`less.SIFProcessProduct`	SIF process result.
`less.CHMProduct`	Canopy height model.
`less.SceneElementRef`, `less.SceneElementRows`	Unified rows for Mesh, Turbid, and Terrain results.

Projects, resources, and serialization¶

API	Purpose
`less.Project`	Manages a scene, named sensors, resources, and task snapshots.
`less.ProjectValidationReport`, `less.ValidationIssue`	Project validation results.
`less.SnapshotInfo`	Remote-task snapshot metadata.
`less.ProjectResource`, `less.ResourceRegistry`	Project resources and checksums.
`less.load_scene`	Loads a scene from a file.

Principal Project methods are create(), open(), add_sensor(), build(), simulate(), validate(), save(), pack(), and export_snapshot(). See Scene and Project Serialization.

Scene generation and utilities¶

API	Purpose
`less.place`	Grid, random, and Poisson-disc instance placement.
`less.asset_path`	Locates a bundled example mesh by filename.
`less.CrownGenerator`, `less.CrownShape`, `less.LeafAngle`	Parametric crown generation.
`less.SunPosition`, `less.compute_sun_position`, `less.compute_day_of_year`	Solar-position calculations.
`less.SolarSpectrum`, `less.SpectrumLibrary`, `less.MaterialDB`	Solar, material, and spectral databases.

Backends, capability checks, and errors¶

API	Purpose
`less.list_backends`	Lists discoverable backends.
`less.list_backend_features`	Lists feature names.
`less.available_features`	Lists features executable in the current environment.
`less.can_use`	Tests whether a feature can execute.
`less.feature_status`	Returns feature status and explanation.
`less.backend_capability_matrix`	Returns the backend capability matrix.
`less.BackendFeature`, `less.BackendFeatureStatus`, `less.BackendInfo`	Feature and device information types.
`less.BackendUnavailableError`	Requested backend is unavailable.
`less.BackendFeatureUnavailableError`	Requested native feature is unavailable and no fallback was performed.

Public API boundary¶

This reference contains interfaces intended for user code. Names beginning with an underscore, _native_optix, _native_vulkan, _native_embree, native scene managers, GPU buffers, artifact validators, and debug hooks are implementation details and are not public APIs.