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Frontiers of Information Technology & Electronic Engineering
ISSN 2095-9184 (print), ISSN 2095-9230 (online)
2016 Vol.17 No.3 P.250-257
Fast implementation of kernel simplex volume analysis based on modified Cholesky factorization for endmember extraction
Abstract: Endmember extraction is a key step in the hyperspectral image analysis process. The kernel new simplex growing algorithm (KNSGA), recently developed as a nonlinear alternative to the simplex growing algorithm (SGA), has proven a promising endmember extraction technique. However, KNSGA still suffers from two issues limiting its application. First, its random initialization leads to inconsistency in final results; second, excessive computation is caused by the iterations of a simplex volume calculation. To solve the first issue, the spatial pixel purity index (SPPI) method is used in this study to extract the first endmember, eliminating the initialization dependence. A novel approach tackles the second issue by initially using a modified Cholesky factorization to decompose the volume matrix into triangular matrices, in order to avoid directly computing the determinant tautologically in the simplex volume formula. Theoretical analysis and experiments on both simulated and real spectral data demonstrate that the proposed algorithm significantly reduces computational complexity, and runs faster than the original algorithm.
Key words: Endmember extraction, Modified Cholesky factorization, Spatial pixel purity index (SPPI), New simplex growing algorithm (NSGA), Kernel new simplex growing algorithm (KNSGA)
创新点:本文提出采用空间像元纯度指数(SPPI)来确定KNSGA算法中的初值,提高了算法的稳定性。此外,对于KNSGA中耗时的单形体体积计算,利用改进的Cholesky分解的思想,将求单形体体积最大值转化为寻找矩阵对角元素最大值,进而降低了算法的时间复杂度。
方法:SPPI越小,则像素的纯度越高,因此将具有最小SPPI的像素作为KNSGA的初始值。原始的KNSGA提取端元的过程是循环计算单形体体积值,即每增加一个端元则计算一次端元构成的单形体体积值,直至找到所有端元为止;利用改进的Choelsky分解的快速实现算法,只需在所有端元都找到之后进行一次单形体体积计算。改进后的算法简化了算法的运算复杂度,加快了算法的实现过程。
结论:本文研究针对KNSGA的改进加速算法,利用SPPI解决初值问题,利用Cholesky分解降低计算时间复杂度。实验结果表明,提出的改进算法在算法稳定性和效率上相比原算法都有一定程度提高。
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DOI:
10.1631/FITEE.1500244
CLC number:
TP75
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On-line Access:
2024-08-27
Received:
2023-10-17
Revision Accepted:
2024-05-08
Crosschecked:
2016-02-23