Nonlinear Spectral Unmixing With a Linear Mixture of Intimate Mixtures Model

We present a new model for nonlinear spectral mixing observed in hyperspectral imagery and demonstrate how this model can be used for unmixing and obtaining abundance maps. The model is based on the idea that a single pixel can contain several spatially segregated areas containing different mineral mixtures and fuses Hapke's radiative transfer model for intimate mineral mixtures with the traditional linear mixing model. The resulting model allows great flexibility for generating spectra, provides abundance coefficients in terms of total relative ground cover for each endmember, and can be reduced to several other nonlinear mixing models by an appropriate choice of the parameters. Experiments on laboratory mineral mixtures and real hyperspectral imagery show reduced reconstruction errors and more accurate abundance coefficients compared with the linear mixing model or the recently introduced multimixture pixel model. Moreover, the reconstruction error improvement can be used as a per-pixel measure of the size of the intimate mixing component.