Instruments
Passive Optical
Scene Generator
The Scene Generator Module is in charge of simulating the observed scene, the energy arriving to the instrument detector elements. The simulation chain of the Scene Generator Module starts from the geo/bio-physical variable that is the target of the mission (the soil moisture, the salinity of the oceans, the chlorophyll, etc.). The electromagnetic radiation has a different response depending on the terrain properties and the environment (atmosphere, clouds, etc.). To model this response a Radiative Transfer Model (RTM) is applied to the input geo/bio-physical map. The RTM calculates either the reflectance (the reflected energy at Top-Of-Canopy, the TOC image), or directly the Top-of-Atmosphere image (TOA), which includes the propagation of the electromagnetic radiation through the atmosphere. Clouds also have an impact on the propagation of the energy.
The composing Blocks of the Scene Generator are the following:
- The Resampling Block interpolates the input map in bio/geo-physical variable or TOC to the observation area.
- The Class Map Block classifies the landcover type of each pixel (vegetation, ocean, coastal area, urban area, etc.)
- The Forward Model Block calculates the reflectance or reflectivity, depending on the Radiative Transfer Model and the landcover type of each pixel. The Atmosphere and Clouds Simulator applies the atmospheric radiative transfer model to the reflectance (Top-of-Canopy image), in order to calculate the Top-of-Atmosphere image
The simulation flow of the Scene Generator Module is shown in the diagram below:
Lookup tables (vulcan 1, haze 1, visibility 20) for Atmosphere Simulator Block BIBLOS conducts atmosphere simulation calculations based on lookup tables. For that reason it is necessary to provide a set of most common used LUTs. The package includes subset of LUTs for parameters (names in brackets represents values that should be used in config files):
Atmosphere: u.s. standard (afglus)
Vulcan: background (1)
Haze: rural (1)
Visibility: 20 km (20)
Precipitable water: 5 kg/m^2 (5), 15 kg/m^2 (15) and 30 kg/m^2 (30)
Season: spring-summer (1) and fall-winter (2)
Lookup tables (vulcan 1, haze 1, visibility 10) for Atmosphere Simulator Block BIBLOS conducts atmosphere simulation calculations based on lookup tables. For that reason it is necessary to provide a set of most common used LUTs. The package includes subset of LUTs for parameters (names in brackets represents values that should be used in config files):
Atmosphere: u.s. standard (afglus)
Vulcan: background (1)
Haze: rural (1)
Visibility: 10 km (10)
Precipitable water: 5 kg/m^2 (5), 15 kg/m^2 (15) and 30 kg/m^2 (30)
Season: spring-summer (1) and fall-winter (2)
Lookup tables (vulcan 1, haze 1, visibility 5) for Atmosphere Simulator Block BIBLOS conducts atmosphere simulation calculations based on lookup tables. For that reason it is necessary to provide a set of most common used LUTs. The package includes subset of LUTs for parameters (names in brackets represents values that should be used in config files):
Atmosphere: u.s. standard (afglus)
Vulcan: background (1)
Haze: rural (1)
Visibility: 5 km (5)
Precipitable water: 15 kg/m^2 (15)
Season: spring-summer (1) and fall-winter (2)
Biblos.AtmosphereSimulator The Atmosphere Simulator Block is in charge of the propagation of reflected/emitted light from the surface through the atmosphere for an Earth surface pointing scene. The execution of an atmospheric RTM for the simulation of the TOA radiance can be computationally very demanding for large size scenes. The option selected for BIBLOS is to generate an atmospheric Look-Up-Table (LUT) with several combinations of atmospheric/illumination/viewing conditions. This is a flexible configuration, as the user can modify or change the LUT with a RTM that suits their mission. The LUT will also be used later in Level-2 Retrieval Module and. The main atmospheric parameters that characterize the optical properties of the atmosphere are Aerosol type, Aerosol Optical Thickness, Water Vapour Column, Carbon Dioxide, Ozone Content. Package contains B_AtmosphereSimulator class and B_LUTRead header file that deals with LUT reading.
Lookup tables (tropical) for Atmosphere Simulator Block BIBLOS conducts atmosphere simulation calculations based on lookup tables. For that reason it is necessary to provide a set of most common used LUTs. The package includes subset of LUTs for parameters (names in brackets represents values that should be used in config files):
Atmosphere: tropical (afglt)
Vulcan: background (1)
Haze: maritime (4)
Visibility: 20 km (20)
Precipitable water: 30 kg/m^2 (30) and 50 kg/m^2 (50)
Season: spring-summer (1) and fall-winter (2)
Lookup tables (subarctic) for Atmosphere Simulator Block BIBLOS conducts atmosphere simulation calculations based on lookup tables. For that reason it is necessary to provide a set of most common used LUTs. The package includes subset of LUTs for parameters (names in brackets represents values that should be used in config files):
Atmosphere: subarctic summer (afglss) and subarctic winter (afglsw)
Vulcan: background (1)
Haze: rural (1)
Visibility: 20 km (20)
Precipitable water: 15 kg/m^2 (15)
Season: spring-summer (1) and fall-winter (2)
Tool: Tiff to NetCDF converter BIBLOS works with NetCDF format for the images. This is a tool to convert Tiff to NetCDF. It is external to BIBLOS, the user shall convert the image offline. THe package includes an executable, a README file (with instructions) and an example auxiliary file.
Biblos.SceneGeneration This is a module composed of Biblos.Resampling and Biblos.Atmosphere blocks.The Scene Generator Module is in charge of simulating the observed scene, the energy arriving to the instrument detector elements. The simulation chain of the Scene Generator Module starts from the geo/bio-physical variable that is the target of the mission (the soil moisture, the salinity of the oceans, the chlorophyll, etc.). The electromagnetic radiation has a different response depending on the terrain properties and the environment (atmosphere, clouds, etc.). To model this response a Radiative Transfer Model (RTM) is applied to the input geo/bio-physical map. The RTM calculates either the reflectance (the reflected energy at Top-Of-Canopy, the TOC image), or directly the Top-of-Atmosphere image (TOA), which includes the propagation of the electromagnetic radiation through the atmosphere. Clouds also have an impact on the propagation of the energy.