Abstract
Digital Surface Model (DSM) derived from high resolution satellite imagery is important for various applications. GFDM is China’s first civil optical remote sensing satellite with multiple agile imaging modes and sub-meter resolution. Its panchromatic resolution is 0.5 m and 1.68 m for multi-spectral images. Compared with the onboard stereo viewing instruments (0.8 m for forward image, 0.65 m for back image, and 2.6 m for back multi-spectrum images) of GF-7, a mapping satellite of China in the same period, their accuracy is very similar. However, the accuracy of GFDM DSM has not yet been verified or fully characterized, and the detailed difference between the two has not yet been assessed either. This paper evaluates the DSM accuracy generated by GFDM and GF-7 satellite imagery using high-precision reference DSM and the observations of Ground Control Points (GCPs) as the reference data. A method to evaluate the DSM accuracy based on regional DSM errors and GCPs errors is proposed. Through the analysis of DSM subtraction, profile lines, strips detection and residuals coupling differences, the differences of DSM overall accuracy, vertical accuracy, horizontal accuracy and the strips errors between GFDM DSM and GF-7 DSM are evaluated. The results show that the overall accuracy of both is close while the vertical accuracy is slightly different. When regional DSM is used as the benchmark, the GFDM DSM has a slight advantage in elevation accuracy, but there are some regular fluctuation strips with small amplitude. When GCPs are used as the reference, the elevation Root Mean Square Error (RMSE) of GFDM DSM is about 0.94 m, and that of GF-7 is 0.67 m. GF-7 DSM is more accurate, but both of the errors are within 1 m. The DSM image residuals of the GF-7 are within 0.5 pixel, while the residuals of GFDM are relatively large, reaching 0.8 pixel.
Highlights
High-resolution stereo mapping satellites can quickly acquire high-precision DigitalSurface Model (DSM) of large areas [1,2,3,4]
Digital Surface Model (DSM) is a description of the basic topographic elements about the earth’s surface [5,6], which is widely used in navigation, mapping, geological disaster monitoring, natural resource investigation, and environmental monitoring [7,8,9,10]
DSMs derived from GF-7 and GFDM are respectively compared with with the using the the calculated calculated differences differences after after co-registration co-registration the high high precision precision reference reference DSM
Summary
Surface Model (DSM) of large areas [1,2,3,4]. DSM is a description of the basic topographic elements about the earth’s surface [5,6], which is widely used in navigation, mapping, geological disaster monitoring, natural resource investigation, and environmental monitoring [7,8,9,10]. Since DSM for a large area of the earth was generated by SPOT satellite using stereo observation for the first time in 1986 [11], high-resolution stereo mapping satellites have been gradually increased and developed [12,13,14,15]. China’s first civilian high-resolution optical transport mapping satellite, Ziyuan-3 satellite, was Launched on 9 January 2012.
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