摘要:
缨帽变换是影像增强中最常见的一种方法,已在遥感中得到了广泛的应用。但是,由于高分辨率卫星传感器(例如GF-6 WFV)通常缺乏短波红外波段,所以用常规的Gram-Schmidt(G-S)正交化方法得到的缨帽变换系数通常会存在湿度分量失真的问题。为此,文章选取了覆盖不同地区、不同时相、不同季节的12幅GF-6 WFV影像和6幅同步的Landsat8 OLI影像,首先利用GF-6和Landsat8的同步影像进行湿度分量回归,确定GF-6 WFV传感器的湿度分量系数,进而采用G-S逆推算法依次推导出亮度、绿度及其他分量,开发出了GF-6 WFV传感器的缨帽变换系数。研究发现: ①通过调整缨帽变换湿度分量的推导顺序,即先推导湿度分量再推导亮度和绿度等分量,可以较好地推导出GF-6 WFV传感器的缨帽变换系数,并解决传统G-S正交化方法中存在的湿度分量失真问题; ②GF-6 WFV缨帽变换各分量具有稳定的特征,地物在不同分量组成的特征平面内具有典型的“缨帽”分布特征; ③尽管GF-6 WFV传感器与Landsat8 OLI传感器在波段设置和光谱响应方面存在一定差异,但它们缨帽变换对应分量之间具有较好的一致性,相关系数仍高达0.8。
Abstract:
Tasseled cap transformation (TCT), one of the most common methods in image enhancement, has been extensively applied in remote sensing. However, high-resolution satellite sensors (like GF-6 WFV) usually lack short-wave infrared bands, leading to distorted wetness components in TCT coefficients obtained using the conventional Gram-Schmidt (G-S) orthogonalization method. Hence, this study selected 12 GF-6 WFV images covering different regions, temporal phases, and seasons, as well as six synchronous Landsat8 images for wetness component regression, determining the wetness component coefficient of the GF-6 WFV sensor. Furthermore, it employed the inversed G-S algorithm to deduce the brightness, greenness, and other components, deriving the TCT coefficient of the GF-6 WFV sensor. This study found that: ①Adjusting the derivation order of the wetness component in TCT (that is, the derivation of the wetness component comes before that of other components like brightness and greenness) allows more effective derivation of the TCT coefficient of the GF-6 WFV sensor, avoiding the distortion of the wetness component; ②The TCT components of the GF-6 WFV sensor exhibited stable characteristics, with surface features displaying a typical “tasseled cap” distribution in the feature plane composed by various TCT components; ③Despite the differences in band setting and spectral response, GF-6 WFV and Landsat8 OLI sensors manifested high consistency in corresponding TCT components, with a correlation coefficient of up to 0.8.
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