Foreword to the Special Issue on Spectral Unmixing of Remotely Sensed Data

MORE than two decades after the first efforts toward the application of spectral mixture analysis techniques to remotely sensed data [1], [2], effective spectral unmixing still remains an elusive exploitation goal. Regardless of the available spatial resolution, the spectral signals collected in natural environments are invariably a mixture of the signatures of the various materials found within the spatial extent of the ground instantaneous field view of the remote sensing imaging instrument [3]. The availability of hyperspectral imaging instruments [4] (also called imaging spectrometers [5]) with a number of spectral bands that exceeds the number of spectral mixture components has fostered many research efforts. Spectral unmixing has been a very active research area in recent years since it faces important challenges [6], [7]. In order to present the state-of-the-art and most recent developments in this area, it is our great pleasure to introduce this special issue on Spectral Unmixing of Remotely Sensed Data of the IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING. The special issue is the first one of its kind in the literature since this topic has not been addressed in the form of a dedicated monograph in any other journal in the past. The special issue brings together distinguished experts to provide a remarkable sample of latest-generation techniques in the field. A large number of submissions (45) were received for this special issue, of which 20 papers were selected after rigorous review. In the remainder of this foreword, we review key issues and topics of current interest related to spectral unmixing that are covered by this special issue.