The RGB mosaic system is an automatic tool to generate a mosaic over the Alps that provides the last SENTINEL-2 color images available, with a cloud coverage of less than 30% of the entire scene. The system is composed of open source software for processing and visualization tasks and the Data Exchange Server tool (DES) tool, developed by Eurac Research, to automatize server-based tasks. The processing of the images uses a python code and GDAL libraries to estimate cloud and no-data coverage in each tile and to optimize the images for a better visualization. The DES is useful to automatize images downloading, to run the processing tasks in the right order and to update the mosaic and metadata when the processing is over. The result is shared through a WMS (Web Map Service) layer and in a web page for a quick look.

1. Automatic system to generate an
RGB mosaic of the Alps
A. Vianello, M. Amatori, A. Jacob, S. Tritini, B. Ventura

2. RGB mosaic system

3. Goal: Provide the latest image without clouds all
over the Alps
RGB mosaic system

4. Problem: The Alps are often covered by clouds
Goal: Provide the latest image without clouds all
over the Alps
RGB mosaic system

5. Tile information:
• UTM grid number
• Acquisition date
• Cloud coverage %
Tile overlapping
Rule:
Every tile is updated when a new one
with a cloud coverage and no-data
less then 30% is downloaded
RGB mosaic system

6. 32TPS tile history

7. Spatial resolution: 1 pixel = 10 meters
100 Km
Screenshot date: 15-11-2019
Final RGB mosaic

8. Spatial resolution: 1 pixel = 10 meters
100 Km
Screenshot date: 15-11-2019
Final RGB mosaic
2 km

9. Spatial resolution: 1 pixel = 10 meters
100 Km
Screenshot date: 13-11-2019
Final RGB mosaic

10. Images processing: RGB generation and color stretching
Images automatization for images download, processing,
publication
Web Map Service for the Mosaic
DES Data Exchange Server is a software developed by Eurac
Research to facilitate automatization of tasks
PostgreSQL + PostGIS are used to store the UTM grid layer
and to update the attribute values
Development tools

11. Sen2Core
processing
Daily S2-
images
download
Unzip and move
files
RGB image
creation
Update layer store
in geoserver for the
single tile
Update group:
layer's order with
most recent tile on
the top
DES task to run bash script and python code
Update grid layer
with tile infoREADY
Workflow
File not
corrupted No Data < 30%
Cloud
coverage < 30%

12. Additional results
Flood event in Venice countryside, autumn 2018
Before After

13. Outlook:
To improve the quality of the mosaic we will use a Web Coverage Processing Service (WCPS)
to update the image with a pixel based approach.
Tile based Pixel based

14. Mosaic pixel based for 2019 in South Tyrol
http://sao.eurac.edu

15. Map: http://sdi.eurac.edu/sao_rgb/
WMS service: http://saocompute.eurac.edu/geoserver/ows?SERVICE=WMS/
Mosaic layer name: EURAC_S2_RGB_10m_alps_last
Tile layer name example: SENTINEL2:T33TWN
Eurac Research WMS service
Data provider
Copernicus Open Access Hub: https://scihub.copernicus.eu/

16. Map: http://sdi.eurac.edu/sao_rgb/
WMS service: http://saocompute.eurac.edu/geoserver/ows?SERVICE=WMS/
Mosaic layer name: EURAC_S2_RGB_10m_alps_last
Tile layer name example: SENTINEL2:T33TWN
Eurac Research WMS service
Copernicus Open Access Hub: https://scihub.copernicus.eu/
Thank you
andrea.vianello@eurac.edu
Data provider