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.

中文翻译：

---

用 C-HH SAR 数据映射芦苇的时间滤波器

摘要 我们比较了传统的空间滤波器和多时间滤波器，以去除合成孔径雷达 (SAR) 数据中的斑点，用于绘制芦苇。SAR 星座具有更快速的重访能力，允许生成一堆 SAR 数据并使用多时相滤波器来减少散斑。GAMMA 软件为 SAR 处理提供了多时态滤波器，我们将其中两个滤波器与传统的增强型 Lee 滤波器和 Lee 滤波器进行了比较。我们使用三个标准评估过滤器：(1) 目视检查，(2) 信号电平比，以及 (3) 等效外观数 (ENL)。这项研究的结果表明，多时相过滤器能够减少地表水和陆地区域的斑点，以及由于保留了有助于检测斑块边界的分辨率和纹理，从而改进了芦苇斑块的检测。GAMMA 多时态滤波器的信号电平比约为 1.0，其他滤波器约为 0.9。增强的 Lee 和两个多时相滤波器产生的 ENL 相等，约为 6。 然而，由于斑块大小小，并且与香蒲和其他覆盖类型的反向散射相似，芦苇斑块很难与其他类型的水淹植被用 C-HH 分开强度而已。