7th Workshop on Forest Fire Management - EARSeL, European ...

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II - VALIDATION OF RS PRODUCTS FOR FIRE MANAGEMENT
sitivity of the spectral data to their presence. This work aims for assessing
the relationship between the main post-fire surface materials which are
consequence of the combustion process (black carbon, ash and vegetation
remains) and hyperspectral data. In the same way, this work compares the
sensitivity of the original reflectance values against the transformed data
(first derivative and absorption features analysis).
2 - Study area
The specific fire study site is located in Peñaflor experimental station (PES)
(Zaragoza, Spain). It is a south-facing slope of 12° placed in a semiarid
environment with a Mediterranean shrubland. A 15x3m section in the lowest
sector of the slope was burnt in an experimental fire allowing the fire
to spread naturally to the remaining slope.
3 - Methodology
3.1 - Obtaining of field data
Two different techniques were used for the obtaining of field data: (1) high
spatial resolution photography using a Reflex Nikon D100 digital camera
and (2) field spectrometry with the field spectrometer Avantes AvaSpec
which registers reflectance in the 400-1800 nm bandwidth with a 0.57 nm
spectral sampling in the VIS-NIR range and a 3.5 nm spectral sampling in
the SWIR range.
The obtaining of both informations was made using a metallic structure
(3x3x2m) with a mobile system to hold both devices in such a way that
both registered, from the nadir, the same surface. To control the surface
registered by the spectrometer, its field of view was restricted to a 10º
angle thus generating a circular surface of capture of 30 cm of diameter
(Figure 1). From every photograph we retained only this central surface
avoiding distortion problems and metallic structure shadows.
We applied a regular sampling in the rectangular section and a random one
in the remaining burnt slope, building a database of 305 points.