Published on 24 September 2024

swissEO S2-SR

Optical satellite data (Sentinel-2) used to show the reflectances of the land surface for the four channels Red, Green, Blue and near Infrared in a spatial resolution of 10 metres.

Switzerland is mapped by four orbits of the satellite overflight (see graphic below). The overlapping orbits result in a complete image of Switzerland approximately every three to five days, but the usefulness of the data is heavily dependent on meteorological conditions at the moment of overflight, as the imaging sensor cannot see through clouds. In addition to the already applied localisation of the data, a co-registration of the data optimised for Switzerland is applied for a sub-pixel positional accuracy and and a reprojection is carried out in a uniform coordinate system. Also included are optimised quality layers with masks for clouds (and cloud shadows) and topographic shadows.

Coverage of Swiss territory depending on the orbit of the satellite.

Data visualisation and availability

The most recent dataset can be displayed as a true color image in the BGDI map viewer at https://map.geo.admin.ch/?layers=ch.swisstopo.swisseo_s2-sr_v100. In the BGDI WMS, this dataset can be displayed using the «ch.swisstopo.swisseo_s2-sr_v100» layer.

It currently takes around three days to process a newly recorded data set after it has been recorded. To find out which data acquisitions are planned for the current and following week, please visit the website of the European Space Agency (ESA) to check the recording schedules of the Sentinel-2 satellites.

In order to view a time series, there is a catalogue or a machine-readable list of the recorded and processed data sets, as well as a further list with the days on which no data was recorded or the cloud cover was greater than 80% and the data was therefore not processed. To display older data sets as TrueColor RGB images in the BGDI map viewer, a URL parameterisation must be carried out. The <id> in the following link is replaced by the timestamp of the data acquisition in the format “yyyy-mm-ddtHHMMSS” (for example: 2025-01-01t235959).

https://map.geo.admin.ch/index.html?layers=WMS||s2-sr_v100_<id>||https://wms.geo.admin.ch/?item=<id>||ch.swisstopo.swisseo_s2-sr_v100||1.3.0

For example for the 2024-05-10t102021 dataset:

https://map.geo.admin.ch/index.html?layers=WMS||s2-sr_v100_2024-05-10t102021||https://wms.geo.admin.ch/?item=2024-05-10t102021||ch.swisstopo.swisseo_s2-sr_v100||1.3.0

Additional information

• Technical details

  • Coordinate system: CH1903+ LV95 (EPSG:2056)
  • Resolution: 10m
  • Temporal resolution: for each overflight (approx. 2-3 times per week)
  • Availability: Orbits that are at least 20% cloud-free.
  • Data Format: Cloud Optimized GeoTIFF (COG)
  • Interfaces: STAC, WMS
  • Source code used for the production: https://github.com/swisstopo/topo-satromo/

• Product contents

  The swissEO S2-SR product contains seven elements all available for direct download:*

  • BANDS-10M: True color orthophoto of the RGBN Copenicus bands (B4, B3, B2, B8) with a 10m resolution. (Preview, Sample)
  • BANDS-20M: Red-Edge, Near Infrared and Shortwave Infrared of Copernicus bands (B5, B8A, B11) with a resolution of 20m. (Sample)
  • CLOUDPROBABILITY-10M: This raster contains the probability of cloud cover for each pixel in the satellite image. (Sample)
  • MASKS-10M: This raster contains masks for various features such as terrain shadows, clouds, and cloud shadows of the satellite image. (Sample)
  • METADATA: JSON file with all necessary information for every element of the product. (Sample)
  • REGISTRATION-10M: This raster contains registration information for the satellite data, including displacement in the x and y directions. (Sample)
  • THUMBNAIL: A resized JPEG image of the satellite image to enable a quicker preview. (Preview)

  * All samples and previews refer to the latest product update.

• Detailed product information

  The data basis is provided by Sentinel-2 L2A data from the European Space Agency (ESA). Sentinel-2 comprises three satellites (Sentinel-2A, Sentinel-2B and Sentinel-2C). The Sentinel-2 sensors capture data in 13 spectral bands of visible light across the near-infrared range to short-wave infrared with spatial resolutions of 10 m, 20 m and 60 m. For the ‘swissEO S2-SR’ product, bands B2, B3, B4 and B8 (blue, green, red and near infrared) are processed at a spatial resolution of 10 m, and bands B8A, B11 and B5 (narrow near infrared, shortwave infrared and red edge) at a spatial resolution of 20 m.

  The CloudScore+ data, specially developed for Sentinel-2 data, is used to identify clouds and cloud shadows. This algorithm calculates a spectral distance value for each pixel relative to a theoretically clear reference, enabling an assessment of cloud probability. The masking process identifies both direct cloud pixels and their shadow areas. Clouds above a threshold value of 40% cloud probability are masked. A lower threshold value of 20% is applied for cloud shadows, but only in the projection corridor of clouds that have already been identified. In order to detect semi-transparent cloud edges and eliminate isolated misclassifications, morphological filter operations are applied to the combined cloud and cloud shadow mask. Both the binary cloud and cloud shadow mask and the continuous cloud probability layer itself are provided, allowing you to define your own threshold values if required.
  

  Terrain shadow detection is performed using a two-step approach that takes into account both the illumination angle and direct shadow casting. In the first step, the illumination angle is calculated for each pixel, which is determined from the sun's zenith angle, the sun's azimuth, and the local slope and orientation. This angle indicates how directly the sun's rays hit the ground surface. 0° means perfect illumination from above, while high values towards 90° mean extreme oblique illumination. In a second step, direct shadows are identified using the swissSURFACE^3D digital surface model. The shadows are simulated depending on the position of the sun at the time of recording (deviation ±2.5 min). The identified direct shadows are marked with a value of 100 in the terrain shadow mask.
  

  Images from the same orbital track of a satellite over Switzerland are combined into a mosaic. This optimises data consistency and reduces artefacts at the edges of the images. If two orbital tracks from different satellites are available, two mosaics are provided, one for each orbital track.

  Co-registration is performed by comparing the Sentinel-2 images with a reference image (S2 Global Reference Image, GRI). An image matching algorithm based on the red spectral band (B4) is used, as this band is particularly high in contrast and clearly shows distinctive landscape features. The algorithm searches for matching image features between the current image and the reference image and calculates displacement vectors in the X and Y directions. The displacement vectors are applied to all delivered bands and are also made available for traceability purposes.

• Additional content information

  • swissEO S2-SR - Additional content information

    PDF380.18 kB25 March 2025

Download raw data

Raw data can be downloaded via the collection «ch.swisstopo.swisseo_s2-sr_v100» in the STAC interface of the BGDI:

• Download interface: swissEO S2-SR: Optical satellite data (Sentinel-2) (admin.ch)
• Download API documentation: REST Interface: Spatial Temporal Asset Catalog API (admin.ch)
• Google Earth Engine: S2-SR Image Collection [projects/satromo-prod/assets/col/S2_SR_HARMONIZED_SWISS]
• Accessing STAC via Python - Introduction (Jupyter Notebook)
• Image processing via Python using STAC (Jupyter Notebook)
• Streaming of swissEO products in QGIS

Terms of use

swissEO may be used, distributed and made accessible. Furthermore,it may be enriched and processed and also used commercially. A reference to the source is mandatory. In the case of digital or analogue representations and publications, as well as in the case of dissemination, the following source references must be attached in any case:

© swisstopo, Contains modified Copernicus Sentinel data [Year]

Further information on the terms of use can be found on the terms of use webpage.