Euro-Mediterranean Wildland Fire Laboratory, a “wall-less” Laboratory for Wildland Fire Sciences and Technologies in the Euro-Mediterranean Region Deliverable D-08-01 Hyperspectral camera: its principles and rules of use

SUMMARY A hyperspectral camera has been acquired by the Department of Geography of the University of Alcalá. The system has been manufactured by Specim (www.specim.fi) at Oulu, Finland. The hyperspectral camera is composed of an ImSpector N17, a SU320-1.7TR NIR CCD camera, a spinning mirror installed in order to scan a 2 dimensional target and a fibre optic downwelling irradiance sensor (FODIS). The FODIS data is used to normalised radiance and derive from that the reflectance. The hyperspectral camera measures 320 pixels in the across scanning direction. The field of view (FOV) in this direction is 24° in total, which results in 0.075° per pixel. In the along track direction the number of pixels is variable. It may vary from 1 to around 500 pixels depending on the application characteristics. Spectral range covered by the hyperspectral camera is from 900 to 1750 nm with a full width at half maximum (FWHM) of 4.5 nm. The hyperspectral camera accuracy has been tested with an Opdima and a Labsphere Spectralon TM white reference panels, showing good results. Hyperspectral measurements of rare earths have been compared with " true " reflectance values from Labsphere. Results show very good agreement regarding the position of the absorption bands. Absolute reflectance values were overestimated by our hyperspectral camera due to the illumination conditions. The hyperspectral camera will be used in forest fire research mainly to estimate fuel moisture content (FMC) as a critical variable in fire danger rating. Additionally, it will be tested to discriminate fire severity levels in experimental fires.