APPLICATION OF AIRBORNE IMAGING SPECTROMETRY SYSTEM DATA TO INTERTIDAL SEAWEED CLASSIFICATION AND MAPPING

The aim of this paper is to test the ability of imaging radiometers to describe the principal seaweed and seagrass beds along the coast of B rittany (France). In this work we used CASI, an instrument with progra mmable narrow bands. On the ground, regions of homogeneous vegetation cover were mapped using differential GPS positioning. Ground spectra w ere recorded with a field spectroradiometer (Spectron SE 590), for sub stratum and different species. Their analysis shows variations in rela tion to pigment characteristics, vegetation structure and environmenta l conditions. An algorithm sequence based on field work and according to the technical sensor characteristics, was developed to discriminate the dominant species. The classified CASI image was compared with gro und data. The main results are the following : (a) the visible wavelen gths allow good discrimination between green, red and brown algae. (b) the infrared wavelengths allow separation of two main types of brown species, seagrasses and the identification of floating seaweed.