DEM4S2


Welcome to the service page DEM4S2.
This application adds the elevation dimension to Sentinel-2 tiles. This 3D view can be used, for example, to assess the influence of relief on land use as seen from space.
 

Summary
  1. Human Machine Interface
  2. Use case


Access to DEM4S2 : https://visioterra.org/DEM4S2/

The Sentinel-2 satellites are part of a constellation whose first mission Sentinel-2A was launched on June 23, 2015. These satellites carry the MSI (Multi-Spectral-Instrument), an optical imager in the visible, near-infrared and mid-infrared range across 13 spectral bands. The swath width of 290 km combined with the high spatial resolution of 10 m produces a large volume of data along an observation segment. To enable data manipulation, Sentinel-2 data have been divided into 100 km by 100 km tiles according to a reference grid called MGRS (Military Grid Reference System). The DEM4S2 altimetry data, used to define relief, can be viewed and downloaded according to this grid. It is possible to view the digital elevation model only by entering the footprint (for example: 33TTG) or by providing the Sentinel-2 product identifier observed on this footprint (for example: S2A_MSIL2A_20240315T100031_N0510_R122_T33TTG_20240315T141852 ).

Digital Elevation Models (DEM) are used to orthorectify Sentinel-2 images in order to eliminate parallax errors due to shooting geometry and relief. As illustrated below, the user can choose which DEM to use. By default, DEM4S2 will present the DEM used for Sentinel-2 orthorectification. Since March 30, 2021, Sentinel-2 data have been orthorectified using the Copernicus DEM (COP-DEM GLO-90 then COP-DEM GLO-30). Depending on the version of the Sentinel-2 production chain, the DEM used for orthorectification may have changed (see: Processing Baseline).
.

Human Machine Interface 

The Human-Machine Interface (HMI) available at https://visioterra.org/DEM4S2 offers users an intuitive experience for accessing elevation data according to the right-of-way specified by a Sentinel-2 product identifier or MGRS tile index.

MGRS grid identifiers can be viewed from the "Sentinel-2 tiling grid kml" file.  

Main features :

  • Selecting an S2/MGRS tile  : The first field allows you to choose the DEM tile to download.

     
  • Choosing the DEM : The Digital Elevation Model to be chosen is one of those used for the orthorectification of Sentinel-2 products (NASADEM, COP DEM GLO-90 then COP DEM GLO-30).
    When the identifier of a Sentinel-2 product is provided, the application selects by default the DEM used for its orthorectification.
     


  • DEM information display : Clicking on the information icon ("i") lists the characteristics of the selected DEM (DEM ID, Integration status, Full name, Spatial coverage, Ground sampling distance, Type...).
    The drop-down menu below provides a detailed explanation of each available field.
  • Display statistics : Statistics calculated on the selected tile show average, standard deviation, minimum and maximum.
  • Viewing the DEM : Users can explore the DEM limited to the footprint of Tile S2. This DEM is displayed with a color table (LUT) whose restitution interval can be selected. The relief effect can be amplified by entering the "Shadow gain" field and a vertical exaggeration factor. By default, shadow gain and vertical exaggeration are initialized to the values 10 and 1 respectively.
  • Downloading DEMs : The ability to download DEMs (tif or WMTS export) allows users to easily integrate these data into their own projects and analyses.

Use cases 

Here is a list of different use cases for which DEM4S2 could be useful

.

  1. Calculating reflectance as a function of local incidence

  2. Understanding how L2A products have been corrected for sun exposure

    Color B/W

  3. Easily display 3D views of scenes