Remote Sensing of the Earth's resources from space-based sensors has evolved in the past forty years from a scientific experiment to a commonly used technological tool. The scientific applications and engineering aspects of remote sensing systems have been studied extensively. However, most of these studies have been aimed at spectral sensors with nonoverlapping bands, which means that the spectral responses of different bands have little between-band overlaps. Numerous conventional spectral sensors have dispersive bands which collect independent data in wavelength order [1]. Conventional spectral imaging system models are convenient for analyzing such sensors. Each band is characterized with a center wavelength and a particular bandwidth. In these models, multispectral imaging (MSI) and hyperspectral imaging (HSI) systems are often analyzed in a geometric context [2]. The output photocurrents of different bands at a scene pixel are considered as elements of a p-dimensional vector X, where p is the number of bands available for the particular imager in question. For convenience, feature space Ψ with orthogonal Cartesian coordinates is commonly used to visualize data. This geometrical view can be leveraged to define spectral data as a convex or a conical set, to describe the linear unmixing problem in terms of simplexes [3], to use subspace projection methods for spectral image processing [4], and to define target subspaces for classification [5], among other applications. Although overlaps between spectral responses of different bands are allowed, and really exist in most current MSI or HSI systems, their influences to the output data are not carefully analyzed yet because they are small enough to be ignored.A motivation for studying overlapping bands has arisen with the advent of adaptive simply-configurable sensors based on Quantum-Dot Infrared Photodetectors (QDIPs) in recent years [6], together with the purpose of better understanding of color vision principle of human eyes, the most popular spectral sensors with three bands. For QDIPs, the spectral responses change continuously with the bias voltages applied. A group of typical spectral responses are shown in Fig. 1 (a) [7]. For human eyes, their three bands are spectral responses of three types of retina cones which are shown in 1 (b) [8]. While these sensors can exhibit their spectral imaging abilities as is known, the spectral responses of these instruments are highly overlapping so that the influence of overlaps to the image processing result is significant. The conventional imaging system model cannot be applied to analyze them directly.In this paper, a generalized geometry-based model is provided for spectral sensors with arbitrary spectral responses. Spectral sensors with both overlapping and non-overlapping bands are both covered. This model starts from the mathematical description of the interaction process between sensor and the radiation from scene reaching the sensor. The radiation power is a function of wavelength. If it is considered as pattern...