Abstract

We compared traditional spatial filters and multi-temporal filters to remove speckle from synthetic aperture radar (SAR) data for mapping Phragmites australis. SAR constellations, with more rapid revisit capability, allow one to generate stacks of SAR data and to use multi-temporal filters for speckle reduction. GAMMA software offers multi-temporal filters for SAR processing, two of which we compared to the traditional Enhanced Lee and the Lee filters. We evaluated the filters using three criteria: (1) visual inspection, (2) signal level ratio, and (3) the equivalent number of looks (ENL). The results of this study show that multi-temporal filters were able to reduce speckle from areas of surface water and land, as well as to improve the detection of Phragmites patches due to preserving the resolution and texture which helped in the detection of the patch boundaries. The signal level ratio was approximately 1.0 with the GAMMA Multi-temporal filter and approximately 0.9 with the other filters. The enhanced Lee and the two multi-temporal filters produced an equal ENL of about 6. However, due to small patch sizes and backscatter similarity with cattails and other cover types Phragmites patches were difficult to separate from other types of flooded vegetation with C-HH intensity only.

摘要

我们比较了传统空间滤波器和多时相滤波器，以去除合成孔径雷达（SAR）数据中的斑点，以绘制芦苇。SAR星座图具有更快速的重访功能，可以生成SAR数据堆栈并使用多时相滤波器来减少斑点。GAMMA软件提供了用于SAR处理的多时相滤波器，我们将其中两个与传统的Enhanced Lee和Lee滤波器进行了比较。我们使用以下三个标准对滤波器进行了评估：（1）目视检查；（2）信号电平比；（3）等效外观数（ENL）。这项研究的结果表明，多时相滤波器能够减少地表水和陆地区域的斑点，并且由于保留了分辨率和纹理，从而有助于检测芦苇斑块，从而提高了芦苇斑块的检测率。 。GAMMA多时相滤波器的信号电平比约为1.0，其他滤波器的信号电平比约为0.9。