Spectral Variability in Hyperspectral Data Unmixing: A Comprehensive Review


The spectral signatures of the materials contained in hyperspectral images (HI), also called endmembers (EM), can be significantly affected by variations in atmospheric, illumination or environmental conditions typically occurring within an HI. Traditional spectral unmixing (SU) algorithms neglect the spectral variability of the endmembers, what propagates significant mismodeling errors throughout the whole unmixing process and compromises the quality of its results. Therefore, large efforts have been recently dedicated to mitigate the effects of spectral variability in SU. This resulted in the development of algorithms that incorporate different strategies to allow the EMs to vary within an HI, using, for instance, sets of spectral signatures known a priori, Bayesian, parametric, or local EM models. Each of these approaches has different characteristics and underlying motivations. This paper presents a comprehensive literature review contextualizing both classic and recent approaches to solve this problem. We give a detailed evaluation of the sources of spectral variability and their effect in HI spectra. Furthermore, we propose a new taxonomy that organizes existing work according to a practitioner’s point of view, based on the necessary amount of supervision and on the computational cost they require. We also review methods used to construct spectral libraries (which are required by many SU techniques) based on the observed HI, as well as algorithms for library augmentation and reduction. Finally, we conclude the paper with some discussions and an outline of possible future directions for the field.



R. A. Borsoi, T. Imbiriba, J.C.M. Bermudez, C. Richard, J. Chanussot, L. Drumetz, J. Tourneret, A. Zare and C. Jutten, "Spectral Variability in Hyperspectral Data Unmixing: A Comprehensive Review," in IEEE Geoscience and Remote Sensing Magazine, vol. 9, no. 4, pp. 223-270, Dec. 2021, doi: 10.1109/MGRS.2021.3071158.
@Article {Borsoi2020HSIReview,
author = {Ricardo Augusto Borsoi and Tales Imbiriba and José Carlos Moreira Bermudez and Cédric Richard and Jocelyn Chanussot and Lucas Drumetz and Jean-Yves Tourneret and Alina Zare and Christian Jutten},
title = {Spectral Variability in Hyperspectral Data Unmixing: A Comprehensive Review},  
journal = {IEEE Geoscience and Remote Sensing Magazine},