“高分四号”卫星正射校正精度分析

Research on Orthorectification Accuracy of GF-4 Satellite Image

探究"高分四号"(GF-4)卫星影像在无精确控制点情况下进行基于有理函数模型的正射校正时,地形因素、参考影像以及高程数据对其结果的精度影响,并给出最适合GF-4卫星正射校正的经验性结论;文章分别对不同地形、不同分辨率的Landsat8参考影像以及不同分辨率的DEM数据进行正射校正实验,并从自动生成的控制点个数以及均方根误差两方面进行了精度分析。结果表明基于有理函数模型的正射校正对于不同的地形有着不同的校正效果,山地整体效果上略好于平原与城市;参考影像的全色波段与GF-4卫星影像的空间分辨率比例在0.8～1.0之间时,正射校正效果最佳;DEM对于GF-4卫星影像垂直方向正射校正效果显著,且分辨率越高校正效果越好。GF-4卫星影像的正射校正精度高低不仅与自身图像所包含的地形地貌有关,而且其参考影像与DEM数据的分辨率也会对精度有影响,宜选用分辨率相近的参考影像以及较高分辨率的DEM数据参与GF-4卫星的正射校正。

In this paper the influence of terrain factors,reference images and elevation data on the accuracy of orthographic correction is explored based on RFM model of GF-4 images without accurate control points,and an empirical summary about the GF-4 satellite Orthorectification is given.The Orthorectification experiments are executed for different terrains and landsat8 reference images with different resolution and different DEM data,and then the precision is analyzed in two aspects,i.e.the automatic generation of control point number and the RMSE.The correction effects of RMF model orthorectification are different for different terrains,and the overall effect of mountain area is slightly better than that of plain and city.When the spatial resolution ratio of panchromatic band of reference image for GF-4 satellite image is between 0.8-1.0,the orthophoto correction has the best effects.DEM has significant effect on vertical correction of GF-4 satellite images,and the effect is improved with the increase of the resolution.At last,some helpful conclusions are obtained in the paper,that is,the accuracy of orthophoto correction of GF-4 satellite image is not only related to the topography and landform contained in the image,but also affected by the resolution of its reference image and DEM elevation data.Additionally,the orthophoto correction can have better results while selecting reference image with similar resolution and DEM data with high resolution.