连 续 投 影 算 法(SPA)是 一 种 使 矢 量 空 间 共 线 性最小化的前向变量选择算法， 它的优势在于提取全波段的几个特征波长， 能够消除原始光谱矩阵中冗余的信息，可用于光谱特征波长的筛选(Continuous projection to calculate method (SPA) is a kind of minimizing vector spatial collinear prior to variable selection algorithm, and it has the advantage of extract all band several characteristics of wavelength, can eliminate redundant information in the original spectral matrix, can be used for spectral characteristic wavelength filter)