Eradiate

Eradiate is a 3D radiative transfer model designed to support calibration/validation activities in the field of remote sensing. For that purpose, it aims at achieving an accuracy better than 1% on the simulation of satellite images. This requires aggregating modelling advances done by multiple scientific communities, and Eradiate is therefore designed to facilitate the integration of new models and algorithms. High accuracy also requires embracing the full complexity of the world: Eradiate therefore uses the Monte Carlo ray tracing method and utilizes the Mitsuba 3 rendering system as its radiometric kernel.

Eradiate is also free software. We want to provide the scientific community with comprehensive, high-quality software, designed as a common platform to share modelling advances. Learn more about this project.

Detailed Feature List #

• Spectral computation
  Solar reflective spectral region

  Eradiate ships spectral data in the solar reflective region (at least from 280 nm to 2500 nm).
  Line-by-line simulation

  These are true monochromatic simulations (as opposed to narrow band simulations). Eradiate provides monochromatic absorption databases covering the [250, 3125] nm interval. User-defined absorption databases are also supported (see the database format).
  Band simulation

  These simulations compute results in spectral bands. The correlated k-distribution (CKD) method with configurable quadrature rule is used. This method achieves a trade-off between performance and accuracy for the simulation of absorption by gases. Eradiate provides CKD-ready absorption databases for the [250, 3125] nm interval, with various spectral bin sizes (100 cm⁻¹, 1 nm, 10 nm). User-defined absorption databases are also supported (see the database format).
  Polarization

  Eradiate optionally supports polarized light simulation. This feature can be switched on or off to achieve the best compromise between accuracy and performance.
• Atmosphere
  One-dimensional atmospheric profiles

  Both standard profiles, e.g. the AFGL (1986) profiles, and customized profiles are supported.
  Plane-parallel and spherical-shell geometries

  This allows for more accurate results at high illumination and viewing angles.
• Surface
  Lambertian, RPV, Ross Thick-Li Sparse, Hapke, Maignan and ocean surface reflection models

  All models can be parametrized against the spectral dimension.
  Detailed surface geometry

  Add a discrete canopy model (either disk-based abstract models, or more realistic mesh-based models).
  Combine with atmospheric profiles

  Your discrete canopy can be integrated within a scene featuring a 1D atmosphere model in a fully coupled simulation.
• Illumination
  Directional or finite-size illumination model

  Eradiate supports both ideal (Delta angular distribution), and realistic (finite angular size) illumination models.
  Many irradiance datasets

  Pick your favourite or bring your own.
• Measure
  Top-of-atmosphere radiance and BRF computation

  An ideal model suitable for satellite data simulation.
  Perspective camera sensor

  Greatly facilitates scene setup: inspecting the scene is very easy.
  Many instrument spectral response functions

  Our SRF data is very close to the original data, and we provide advice to further clean up the data and find the right balance between accuracy and performance.
• Monte Carlo ray tracing
  Mitsuba renderer as radiometric kernel

  We leverage the advanced Python API of a cutting-edge C++ rendering system.
  State-of-the-art volumetric path tracing algorithm

  Mitsuba ships a null-collision-based volumetric path tracer which performs well in many of the cases Eradiate is used for. We also provide a special-purpose path tracing algorithm for plane-parallel geometries that can perform up to 2 orders of magnitude faster than the null-collision algorithm.
• Traceability
  Documented data and formats

  We explain where our data comes from and how users can build their own data in a format compatible with Eradiate's input.
  Transparent algorithms

  Our algorithms are researched and documented, and their implementation is open-source.
  Thorough testing

  Eradiate is shipped with a large unit testing suite and benchmarked periodically against community-established reference simulation software.
• Interface
  Comprehensive Python interface

  Abstractions are derived from computer graphics and Earth observation and are designed to feel natural to EO scientists.
  Designed for interactive usage

  Jupyter notebooks are now an essential tool in the digital scientific workflow.
  Integration with Python scientific ecosystem

  The implementation is done using the Scientific Python stack.
  Standard data formats (mostly NetCDF)

  Eradiate uses predominantly Xarray data structures for I/O.