Newsletter VisioTerra - April/May 2018
“Fire” & “Burnt area” change detection service
View this email in your browser

Change detection services

VisioTerra has developed a fully automated change detection service enabling users to see the history of changes detected in specified monitored areas. See video in English or French.

A first release of this service is applied to “Fire” and “Burnt area” thematics” using the Proba-V 1-day synthesis 100 m ground sampling distance top of canopy (TOC) reflectances. This service is hosted in VisioTerra infrastructure VtWeb but has also been installed in VITO infrastructure in Belgium. The system is presently running continuously and processes the latest scenes in few minutes from their availability.
change detection service

Proba-V on 12 December 2017
Figure 1a shows the Proba-V scene acquired on December 12, 2017 focusing on one of the fire events located in South Sudan. 
Left panel shows this VtProbaV service. User may select the -Server (VisioTerra or VITO), -Thematic (“Fire” or “Burnt area”) and -Tile being the predefined 10°x10° tiles of the Proba-V grid for S1 products. By activating the “Search” button, a temporal chart is displayed showing the “Change score” over three years of Proba-V products processing. Users may focus on a specific time interval. By clicking on a particular point of the curve, the corresponding date is selected and five thumbnails are displayed giving the -Scene to analyse, -Image of differences, -Rolling mean, -Rolling occurrences, and -Rolling standard deviation.

Fig.1a: Proba-V tile observed on 12.12.2017 in “Fire” service.     
scene_to_analyse (1a)      image_of_changes (1b)       fire_animation (1a vs. 1b)

Fig.1b: Image of changes.
“Burnt area”
change detection service

Proba-V on 21 December 2017

“Fire index” or “Burnt area index” are computed by comparing the S1 TOC product with a slicing mean of the 60 previous acquisitions. 
This comparison enables to compute the:
  • Change score” - that matches with the number of “fire pixels” of the number of “burnt pixels” according to the chosen “thematic”,
  • Image of changes” - showing not only “fire” or “burnt” pixels but also the “transparent pixels”, i.e. the pixels that are covered by clouds or that have been eliminated to reduce false alarms (case of “Sun glints” for fire detection or riversides for the burnt area detection).
In fig.2, burnt area C is certainly due to the fires A and B of fig.1 while burn areas D have been produced by fires posterior to the 12 December 2017.

Fig.2a: Proba-V tile observed on 21.12.2017 in "Burnt area" service.     
scene_to_analyse (2a)      image_of_changes (2b)      burnt_area_animation (2a vs. 2b)

Fig.2b: Image of changes.  
VIDEO : Introduction to VtWeb (English and French).
Discover our previous newsletters
Découvrez nos précédentes nouvelles


Lac Tchad vu des satellites

March 2018
Sentinelle des forêts africaines

February 2018
Automatic Fire Detection 

December 2017

Sentinels sur les forêts d'Afrique

November 2017

Training VtPace in Sri-Lanka

October 2017
100th story "Sentinel Vision"

September 2017
Les opinions exprimées dans ce document reflètent uniquement les résultats des travaux et l'opinion de VisioTerra.
The views expressed herein reflect solely the results of the works and the opinion of VisioTerra.

Copyright © 2018 VisioTerra, All rights reserved.

Want to change how you receive these emails?
You can update your preferences or unsubscribe from this list