This document describes Venμs L2A data available on AWS.
The Venµs science mission is a joint research mission undertaken by CNES and ISA, the Israel Space Agency. It aims to demonstrate the effectiveness of high-resolution multi-temporal observation optimised through Copernicus, the global environmental and security monitoring programme. Venµs was launched from the Centre Spatial Guyanais by a VEGA rocket, during the night from 2017, August 1st to 2nd. Thanks to its multispectral camera (12 spectral bands in the visible and near-infrared ranges, with spectral characteristics provided here), it acquires imagery every 1-2 days over 100+ areas at a spatial resolution of 4 to 5m. This dataset has been converted into Cloud Optimized GeoTIFFs (COGs). Additionally, SpatioTemporal Asset Catalog metadata are generated in a JSON file alongside the data. This dataset contains all of the Venus L2A datasets and will continue to grow as the Venus mission acquires new data over the preselected sites.
| Band | Common name | Centre wavelength (nm) |
|---|---|---|
| B1 | coastal | 424 |
| B2 | coastal | 447 |
| B3 | blue | 492 |
| B4 | green | 555 |
| B5 | yellow | 620 |
| B6 | yellow | 620 |
| B7 | red | 666 |
| B8 | rededge | 702 |
| B9 | rededge | 741 |
| B10 | nir08 | 861 |
| B11 | nir09 | 909 |
The Venμs Open Data can be accessed directly in S3. Scenes are organized using the following directory structure:
s3://venus-l2a-cogs/{site}/{YYYY}/{MM}/{DD}/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_D/
where:
site: Collection siteYYYY: Acquisition date's yearMM: Acquisition date's monthDD: Acquisition date's dayYYYYMMDD: Acquisition datehhmmss: Acquisition time
This section describes the assets stored in each directory.
The STAC JSON asset contains the STAC metadata associated with the dataset. This asset is named according to the following naming convention:
s3://venus-l2a-cogs/{site}/{YYYY}/{MM}/{DD}/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_D/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_D_STAC.json
Surface reflectance assets contain integer-coded surface reflectances for each of the 12 Venμs spectral bands, corrected for atmospheric effects, including adjacency effects.
Surface reflectance assets are Cloud Optimized GeoTIFFs (COGs), coded as 16-bit unsigned integers, with a nodata value of 0.
To obtain reflectance values from these files one must multiply by 0.0001 and subtract 0.1, i.e.
reflectance = 0.0001 * DN - 0.1
where DN is the 16-bit unsigned integer value in the file.
Surface reflectance assets are named according to the following naming convention:
s3://venus-l2a-cogs/{site}/{YYYY}/{MM}/{DD}/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_D/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_C_V3-1_SRE_{band}.tif
where:
site: Collection siteYYYY: Acquisition date's yearMM: Acquisition date's monthDD: Acquisition date's dayYYYYMMDD: Acquisition datehhmmss: Acquisition timeband: Band number, prefixed withB(for example,B8)
Flat reflectance assets contain integer-coded surface reflectances for each of the 12 Venμs spectral bands, corrected for atmospheric effects, including adjacency effects and slope effects. Compared to surface reflectance, flat reflectance assets suppress apparent reflectance variations due to the terrain orientation with respect to the sun.
Flat reflectance assets are Cloud Optimized GeoTIFFs (COGs), coded as 16-bit unsigned integers, with a nodata value of 0.
To obtain reflectance values from these files one must multiply by 0.0001 and subtract 0.1, i.e.
reflectance = 0.0001 * DN - 0.1
where DN is the 16-bit unsigned integer value in the file.
Flat reflectance assets are named according to the following naming convention:
s3://venus-l2a-cogs/{site}/{YYYY}/{MM}/{DD}/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_D/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_C_V3-1_FRE_{band}.tif
where:
site: Collection siteYYYY: Acquisition date's yearMM: Acquisition date's monthDD: Acquisition date's dayYYYYMMDD: Acquisition datehhmmss: Acquisition timeband: Band number, prefixed withB(for example,B8)
The Atmospheric and Biophysical parameters asset contains the atmospheric variables used to correct for atmospheric effects.
Atmospheric and and Biophysical parameters assets are Cloud Optimized GeoTIFFs (COGs), each containing two bands coded as 8-bit unsigned integers, each with a nodata value of 0:
- Band 1 contains water vapour content, in g/cm^2, obtained by multiplying the values by 0.05, i.e.
water vapour = 0.05 * DN, whereDNis the 8-bit unsigned integer value - Band 2 contains aerosol optical thickness, obtained by multiplying the values by 0.005, i.e.
aerosol optical thickness = 0.005 * DN, whereDNis the 8-bit unsigned integer value.
This asset is named according to the following naming convention:
s3://venus-l2a-cogs/{site}/{YYYY}/{MM}/{DD}/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_D/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_C_V3-1_ATB_XS.tif
where:
site: Collection siteYYYY: Acquisition date's yearMM: Acquisition date's monthDD: Acquisition date's dayYYYYMMDD: Acquisition datehhmmss: Acquisition time
The Thumbnail asset contains a quicklook of the image, formatted as JPEG.
This asset is named according to the following naming convention:
s3://venus-l2a-cogs/{site}/{YYYY}/{MM}/{DD}/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_D/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_C_V3-1_QKL_ALL.jpg
where:
site: Collection siteYYYY: Acquisition date's yearMM: Acquisition date's monthDD: Acquisition date's dayYYYYMMDD: Acquisition datehhmmss: Acquisition time
The Quality Mask asset defines areas in the product that contain blackfill (nodata) or are filled with content such as cloud. Each band in the Quality Mask represents a particular aspect as described below
| Band Number | Description | Definition |
|---|---|---|
| 0 | No data | If 2, indicates that the area contains nodata If 1, indicates that the area does not contain nodata |
| 1 | Cloud | If 2, indicates that the area contains cloud If 1, indicates that the area does not contain cloud If 0, indicates that the area contains nodata |
| 2 | Haze | If 2, indicates that the area contains haze If 1, indicates that the area does not contain haze If 0, indicates that the area contains nodata |
| 3 | Cloud Shadow | If 2, indicates that the area contains cloud shadow If 1, indicates that the area does not contain cloud shadow If 0, indicates that the area contains nodata |
| 4 | Thin Cirrus | If 2, indicates that the area contains thin cirrus If 1, indicates that the area does not contain thin cirrus If 0, indicates that the area contains nodata |
| 5 | Snow | If 2, indicates that the area contains snow If 1, indicates that the area does not contain snow If 0, indicates that the area contains nodata |
| 6 | Water | If 2, indicates that the area contains water If 1, indicates that the area does not contain water If 0, indicates that the area contains nodata |
This asset is named according to the following naming convention:
s3://venus-l2a-cogs/{site}/{YYYY}/{MM}/{DD}/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_D/VENUS-XS_{YYYYMMDD}-{hhmmss}-000_L2A_{site}_C_V3-1_QUALITY_MASK.tif
where:
site: Collection siteYYYY: Acquisition date's yearMM: Acquisition date's monthDD: Acquisition date's dayYYYYMMDD: Acquisition datehhmmss: Acquisition time
Auxiliary data assets are provided in a subdirectory of the scene directory named DATA. The following files are included:
- Job processing information (
*_JPI_ALL.xml) - Solar angles (
*_SOL_ALL.tif) - Viewing angles (
*_VIE_ALL.tif) - Useful image information (
*_UTI_ALL.xml)
Detailed masks are provided in a subdirectory of the scene directory named MASKS. The following files are included:
- Cloud and shadows mask (
*_CLM_XS.tif) - Edge (nodata) mask (
*_EDG_XS.tif) - Interpolated water vapour and aerosol optical thickness pixel mask (
*_IAB_XS.tif) - Geophysical mask (
*_MG2_XS.tif) - Interpolated pixel mask (
_PIX_XS.tif) - Saturated pixel mask (
_SAT_XS.tif) - Useful image mask (
_USI_XS.tif)