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Introduction

System Overview

Exosilva is composed of two main parts: i) an large archive of satellite observation spanning more than 20 years over the Swiss territory and 2) a near-real time component, using recente satellite aquisition to build an estimate of the current situation. This current state is compared to the archive for every location of the country independently. The various state layer and alerts produced by the system are based on the difference between the current state and the observations available in the archive.

The great advantage of ExoSilva compared to other product of forest monitoring is the contextualisation current observations with respect to the full archive available for each location. Also, in addition to the widely used NDVI, ExoSilva is one of the few system making use of a full archive of land surface temperature.

What ExoSilva is doing for you
  1. Data Management
  2. The ExoSilva manage quite some bytes of Data in the background. Challenges, faced and solved by the system, include the acquisition of the data, their storage and above all the fast access to the data, both for a large spatial extend and for a large time span.

  3. Pre-Processing
  4. The processing carried out in the data preparation steps include among other re-gridding, cloud masking, index calculation and inter-sensor calibration. While the first ones are common, the inter-sensor calibration is one of the key implementation of ExoSilva.

    Indeed, while the long-term archive available in ExoSilva is mainly built based on the MODIS constellation, the NRT component relies mostly on the 10m resolution product of sentinel-2 missions. How did we achive this magic ? We assume that for every location, a stable statistical relationship exist between the different resolution. The years with common observations allowed us to build this calibration layers.

  5. Web platform
  6. Often, in-house projects in Administrative entities successfuly deploy innovative tools, but the failure occurs at the distribution level. With the web platform of ExoSilva, end-users find a intuitive tool to work with. The notification system in place allows anyone to get easily informed on the current forest developments. On the top of the web plateform, ExoSilva offer as well the API for automated solution for custom solutions.

Satellites

ExoSilva has a data archive based on carefully selected satellite constellation. The selected constellations allow the system to rely on stable and long archive of observation while also aiming at a long-term maintenance of the system in the future. Raw data used in ExoSilva are originating from so called multispectral sensors, acquiring information on land in visible and infrared wavelengths. Temperature data (longwave infrared) are also used throughout the ExoSilva system. The selection of constellation for ExoSilva should be soon completed with other high-resolution sensors, such as Landsat-8 OLI and TIRS and Landsat-9 OLI-2 and TIRS.

Satellite Name Image Resolution Frequency Start End
MODIS Terra/Aqua 500x500 m daily 18.02.00 / 4.07.02 31.12.19
Sentinel 2 10x10 m ~3 days 21.09.17 -
Sentinel 3 400x400 m daily 26.04.16 -
Landsat 8/9 30x30m ~4 days ? ?

Forestry Analysis

The documenation page on examples provides different use case of the ExoSilva plateform.

In brief, the near-real time component of ExoSilva can help at detecting forest parcels under heavy stress. Such detections could lead to an on-site inspection by a specialist. It is particularly useful for the detection of relatively small parcels degradation, for example over which accidents of hikers can happen. Also, the detection of change can be used to focus the effort for map updates for example.

The direct access to archive data through ExoSilva allows a fine analysis of land cover development by specialist. Using the archive, damage endured by forest parcels and well as recovery period and stages can be quantitatively defined.

Notifications

Along with the web plateform, the notification system offer an easy way to get update on a forest parcel at a glance. The registration is made easy through the webplatform. The notification system will improve in a near future, with additional information on rapid-change detection.

Note that the default layer to generate notification is based on a generalized layer of boundaries between Swiss communes. If would like a more specific area setup for your very own needs, please get in touch with the team.

API access

The ExoSilva API has a dedicated documentation page. The API enables your team to automate solutions on the top of the ExoSilva archive. The easy access to the archive is also useful for enabling scientist to get access to a plentiful of information on land development.

API limitation

The full API access is reserved for premium users. Non-premium users see their number of API request limited on a daily basis.

Tailored Data and Service Delivery

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