GF-1 WFV图像经验模分解的光谱保真性与水深遥感探测

Spectral fidelity and water depth remote sensing detection of EMD of GF-1 WFV images

水深是海洋环境的重要参数之一,水深遥感反演是水深测量的一种重要手段。经验模分解(EMD)具有剔除小尺度波浪信息,留下大尺度水下地形信息的特性。本文利用EMD对高分一号卫星宽幅影像进行尺度变换,使用光谱相关系数、光谱角、光谱偏差和光谱相对偏差等评价指标,对剩余层图像进行光谱保真性分析;利用改进的对数转换比值模型对原始影像和剩余层图像进行水深反演,并进行相关性分析与精度评价。研究结果表明:(1)评价指标显示EMD变换后影像具有相当的保真性;空间断面分析表明EMD去除了小尺度的噪声信息,保留了水下地形变化信息。(2)经均匀分布的检查点验证,两区域的原图像反演水深和实测水深的相关性较好,相关系数达0.75以上,且两种波段组合的MAE和MRE均不超过2.42m和8.5%。(3)对EMD的全部10层进行水深反演,蓝绿波段的MAE和MRE均不高于1.62m和5.8%;绿红波段的MAE和MRE均不高于1.93m和6.9%。(4)对于不同的波段组合,蓝绿波段组合在各剩余层的水深反演效果明显优于绿红波段,经EMD后的水深反演效果明显提高。(5)20~30m水深段的反演精度整体要高于30~40m,该模型应用于较浅水深段更具优势。

Water depth is one of the important parameters of the marine environment,and water depth remote sensing is an important means of water depth measurement.EMD can eliminate small-scale wave information,leaving large-scale underwater terrain information.The paper uses the EMD to scale the GF-1 WFV image.The spectral fidelity analysis of the remaining layer images was carried out by using spectral correlation coefficient,spectral angle mapper,spectral error and spectral relative error.The paper uses the improved logarithmic transformation ratio model to carry out the water depth inversion of the original image and the remaining layer image,and carry on the correlation analysis and the accuracy evaluation.Research indicates:(1)The evaluation index shows that the image has considerable spectral fidelity after the EMD transformation.Analysis of spatial section shows that the EMD removes the small-scale noise information and retains the underwater terrain change information.(2)The uniform distribution of the checkpoints to verify that,the correlation between the depth of the original image and the measured water depth is better the correlation coefficient is above 0.75,and the MAE and MRE of the two kinds of band combination are not more than 2.42 m and 8.5%.(3)A water depth inversion was performed on all 10 layers of EMD remaining layer.The MAE and MRE of the combination of blue and green bands are not higher than 1.62 m and 5.8%.The MAE and MRE of the combination of green and red bands are no more than 1.93 m and 6.9%.(4)For different combinations of bands,the effect of blue-green band combination in the remaining layers is superior to the green-red band,and the water depth inversion accuracy is improved significantly after EMD.(5)The inversion accuracy of 20-30 m water depth is higher than 30-40 m,which indicates that the model is more suitable for shallow water depth.