Next Article in Journal
Application of Abundance Map Reference Data for Spectral Unmixing
Next Article in Special Issue
Burned Area Mapping of an Escaped Fire into Tropical Dry Forest in Western Madagascar Using Multi-Season Landsat OLI Data
Previous Article in Journal
Transferability of Economy Estimation Based on DMSP/OLS Night-Time Light
Article Menu
Issue 8 (August) cover image

Export Article

Open AccessArticle
Remote Sens. 2017, 9(8), 764;

A Simple Normalized Difference Approach to Burnt Area Mapping Using Multi-Polarisation C-Band SAR

CSIR Meraka Institute, Pretoria 0001, South Africa
Department of Geography & Environmental Studies, Stellenbosch University, Stellenbosch 7600, South Africa
Author to whom correspondence should be addressed.
Academic Editors: Quazi K. Hassan, George P. Petropoulos, Ioannis Gitas and Prasad S. Thenkabail
Received: 12 June 2017 / Revised: 7 July 2017 / Accepted: 19 July 2017 / Published: 31 July 2017
(This article belongs to the Special Issue Remote Sensing of Wildfire)
Full-Text   |   PDF [9532 KB, uploaded 31 July 2017]   |  


In fire-prone ecosystems, periodic fires are vital for ecosystem functioning. Fire managers seek to promote the optimal fire regime by managing fire season and frequency requiring detailed information on the extent and date of previous burns. This paper investigates a Normalised Difference α-Angle (NDαI) approach to burn-scar mapping using C-band data. Polarimetric decompositions are used to derive α-angles from pre-burn and post-burn scenes and NDαI is calculated to identify decreases in vegetation between the scenes. The technique was tested in an area affected by a wildfire in January 2016 in the Western Cape, South Africa. The quad-pol H-A-α decomposition was applied to RADARSAT-2 data and the dual-pol H-α decomposition was applied to Sentinel-1A data. The NDαI results were compared to a burn scar extracted from Sentinel-2A data. High overall accuracies of 97.4% (Kappa = 0.72) and 94.8% (Kappa = 0.57) were obtained for RADARSAT-2 and Sentinel-1A, respectively. However, large omission errors were found and correlated strongly with areas of high local incidence angle for both datasets. The combined use of data from different orbits will likely reduce these errors. Furthermore, commission errors were observed, most notably on Sentinel-1A results. These errors may be due to the inability of the dual-pol H-α decomposition to effectively distinguish between scattering mechanisms. Despite these errors, the results revealed that burnt areas could be extracted and were in good agreement with the results from Sentinel-2A. Therefore, the approach can be considered in areas where persistent cloud cover or smoke prevents the extraction of burnt area information using conventional multispectral approaches. View Full-Text
Keywords: burnt area; synthetic aperture radar (SAR); polarimetric decomposition; Sentinel-1; RADARSAT-2 burnt area; synthetic aperture radar (SAR); polarimetric decomposition; Sentinel-1; RADARSAT-2

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Engelbrecht, J.; Theron, A.; Vhengani, L.; Kemp, J. A Simple Normalized Difference Approach to Burnt Area Mapping Using Multi-Polarisation C-Band SAR. Remote Sens. 2017, 9, 764.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Remote Sens. EISSN 2072-4292 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top