Multi-500 Data Specification

The Multi-500 product is generated by a constellation of satellites carrying identical or highly similar payloads. This product offers high-resolution multispectral imagery suitable for a wide range of applications, including agriculture, environmental monitoring, and spatial planning.

Technical Specifications Overview

• 2 satellites
• Ground Sampling Distance (GSD): 4.75m at Nadir
• Swath Width: 19 km
• Bit Depth: 8, or 12 bits
• Sun-Synchronous Orbit (SSO) at 10:30 hours Local Time Descending Node (LTDN) (Platero) / 09:30 hours LTDN (Menut).
• Swath Resolution: 4096 pixels wide

Spectral Bands

The multispectral payload captures channels in the visible and near infrared spectral range. These channels are designed to align with the corresponding channels in Sentinel 2 imagery.

• Blue: ~480nm
• Green: ~560nm
• Red: ~662nm
• RedEdge 1: ~703nm
• RedEdge 2: ~738nm
• RedEdge 3: ~780nm
• Near Infra-Red: ~840nm
• Panchromatic: ~623nm (Available only on Platero)

File Naming Convention

The file names for Multi-500 data products follow a standard convention as defined in the table below. This convention captures high level metadata in the name to allow for quick and easy visual identification.

Example: mission_L0_raw_000000000X_20211001101205_20211001101210_E72EFC12.extension

L1C Data Product Definition

Collection ID: [mission]-l1C-cogs (e.g. platero-l1C-cogs, menut-l1C-cogs)

Level 1C data products have TOA reflectance units and have been orthorectified with a moderate resolution DEM, resulting in a cartographic product with accurate geolocation.

Applied Processes

A L1C data product is taken as input, and the following processes are performed:

1. Conversion from TOA radiance to TOA reflectance
2. RPC refinement using a global reference image (GRI) and a digital elevation model (DEM)
3. Orthorectification

Assets

All Multi-500 L1C Items in the Collection have the following assets with the corresponding asset field key, file format and descriptions.

Specifications

• Geoaccuracy < TDB m CE90
• DEM resolution 30 m (SRTM 1 arcsecond)

STAC Extensions

• Processing (partially implemented)
• Electro-Optical (band object implemented)
• Item assets (assets object implemented)
• Satellite (Field platform_international_designator implemented)
• Raster (band object implemented)

L1B Data Product Definition

Collection ID: [mission]-l1B-cogs

Level 1B data products have been radiometrically corrected and converted to physical units of TOA radiance (W m⁻² sr⁻¹ um⁻¹). Products are also geometrically corrected, removing spatial distortions due to scale variations, satellite rotation, and warping caused by the curvature of the Earth's surface and viewing angle. Corresponding pixels in each of the bands are co-aligned, permitting accurate band-to-band calculation and multispectral composite imagery. Ancillary and additional platform metadata is included in additional assets.

Applied Processes

A L1A data product is taken as input, and the following processes are performed:

1. Radiometric correction
   • Apply the radiometric coefficients, part of the L1A product assets, to convert L1A DNs into radiance, accounting for dark and flat fields.
2. Geometric correction
   • Perform the band alignment of all bands with respect to the reference one (red band)
   • Apply the RPCs, part of the L1A product assets, to georeference the rasters

Assets

All Multi-500 L1B Items in the Collection have the following assets with the corresponding asset field key, file format and descriptions.

Specifications

• Geoaccuracy < TDB m CE90
• Band alignment < 0.2 pixels
• Radiometric accuracy < TBD %

STAC Extensions

• Processing (partially implemented)
• Electro-Optical (band object implemented)
• Item assets (assets object implemented)
• Satellite (Field platform_international_designator implemented)
• Raster (band object implemented)

L1A Data

Collection ID: [mission]-l1A-cogs

This collection consists of Multi-500 Level-1A data products. Products in this collection have been reconstructed into a common image format. Each of the bands have a relative correction, removing inconsistent illumination generated by sensor characteristics identified in lab-based calibration. Metadata is included that can be used to radiometrically correct the images. Ancillary data from the platform is included in the metadata asset.

STAC Properties

Information about the assets, geometry, and bands can be accessed in STAC via the following standard extensions:

• Electro-Optical Extension
• Item Assets
• View Geometry
• Raster Extension (only bits_per_sample)

In addition, the following custom properties have been added:

• opencosmos:compression: none, lossless, or lossy

Assets

All Multi-500 L1A Items in the Collection have the following assets with the corresponding asset field key, file format and descriptions.

L0 Data

Collection ID: [mission]-l0

This collection consists of Multi-500 Level-0 data products, which are unprocessed outputs from the satellite payload. Level-0 products are the basis from which all other higher level products are produced. This collection contains assets that might not be processable to a higher level product, this normally happens when an acquisition was carried out to test, calibrate, or commission some part of the satellite.

STAC Properties

Information about the assets, geometry, and bands can be accessed in STAC via the following standard extensions:

• Electro-Optical Extension
• Item Assets
• View Geometry
• Raster Extension (only bits_per_sample)

In addition, the following custom properties have been added:

• opencosmos:compression: none, lossless, or lossy
• opencosmos:capture_mode: which mode was used to capture the image, can be snapshot or linescan
• opencosmos:processable: boolean that indicates if the file can be processed to L1A level. Some configurations, like snapshots, cannot be processed to level 1A

Assets

All Multi-500 L0 Items in the Collection have the following assets with the corresponding asset field key, file format and descriptions.

Metadata

This file is included for ease of access to the metadata without needing to decode the binary file. Most of the information contained in this file is also contained in the binary file.

Ancillary

See the common Open Cosmos Ancillary Format.