基于融合和T-分布的SAR图像水灾变化检测

Detection for Flood Change with SAR Images Based on Fusion and T-Distribution

基于融合和T-分布模型,提出了一种新的SAR图像水灾变化检测方法.首先,结合差值法与对数比的优点,根据经验提出了一种新的融合策略,通过融合差值图像和对数比图像可得视觉效果较好的差异图像.然后根据融合后的差异图像的直方图,确定绝对变化类与绝对非变化类两个区间,从而可得两者之间的模糊区间.假设模糊区间的直方图服从T-分布,根据Kittler-Illingworth(KI)阈值选取准则,提出了一种基于T-分布模型改进的KI阈值法(TM_KI),对融合后的差异图像进行阈值分割得到水灾变化结果.通过实验比较,结果分析表明该方法不但能减少相干斑噪声的影响和增强水灾带来的微弱变化信息,而且能有效地检测面积较小的变化区域,从而改善变化检测性能.

Based on fusion and T-distribution model,a new approach for detecting flood changes with multi-temporal SAR images is presented.Firstly,by incorporating the advantages of image differencing and log-ratio operator,a novel fusion strategy based on experience is introduced.Then,the final difference image with better effect in vision can be obtained by fusing with difference image and log-ratio image.According to the histogram of the final difference image obtained by fusion strategy,the two ranges of absolute changed and absolute unchanged classes in the histogram can be got,respectively.Then the fuzzy range between the two ranges is obtained,which are unable to identify changed or unchanged classes.Under the T-distribution assumption of the fuzzy range in the histogram,a thresholding approach based on the Kittler-Illingworth（KI） threshold selection criterion（TM_KI） is proposed.Finally,the change-detection map is produced by using the proposed thresholding procedure to the fusing difference image.Through experimental comparisons,analysis of results confirm the proposed method not only can reduce the affection by speckle noise and enhance the subtle changed areas brought by flooding,but also effectively detect small changed areas,so that this method can improve the performance of change detection.