不同地形条件地面同步光谱定标场对比研究

利用美国ASD公司的FieldSpec Pro FR地面波谱仪,选择5°视场角探头和135cm探头距测试地物高度,开展0°、5°、10°、15°、20°等五种不同地形坡度明、暗地物自然定标场地面波谱测试。通过对比研究不同地形坡度具代表性、能真实反映被测试目标平均自然性的各波谱测试点波谱曲线特征,得出0°、5°地形坡度获取的波谱曲线连续、平滑,信噪比高,没有混入大气水气吸收、仪器噪声等因素导致的剧烈波动、跳跃现象或尖锐锯齿状噪声,波谱特征明显,吸收峰最小值位置清晰可辨,各波谱测试点波谱曲线变化幅度小,整体反射率值变化小,Fe~(2+)、Fe~(3+)、Al-OH、Mg-OH、CO_3~(2-)等分子基团与离子波谱的诊断性波谱特征位置清晰可辨。因此0°和5°坡度地形条件获取的地面同步自然场光谱定标波谱曲线,可以满足航空高光谱遥感数据的大气校正、光谱重建和空、地回归分析等所需的地面波谱数据要求。

A comparative study on ground synchronous spectral calibration test site with different topographic conditions

This paper used FieldSpec Pro FR ground spectrometer produced by ASD Inc.,and chose the probe with FOV of 5°and probe height of 135cm above the test ground object.This paper conducted ground spec-trum test on five different types of natural calibration test site of bright or dark ground obj ect with topo-graphic slopes which respectively were 0°,5°,10°,15°and 20°.The authors selected typical spectrum test points with various topographic slopes where the average naturality of the test target can be revealed,and conducted comparative study on the features of the spectrum curves.According to the results,the spectrum curves acquired are consecutive and smooth with high signal-to-noise ratio while the topographic slope is 0°or 5°,and they are absent of fluctuating and chattering phenomenon or sharply serrated noise.With obvious spectrum features,the position of the minimum absorption peak is clear,and the extent of variation of spec-trum curve of each spectrum test point is limited.The variation rate of the overall reflectivity value is low, and the characteristic positions of the diagnostic spectrum of molecular groups (including Fe2+,Fe3+,Al-OH,Mg-OH,CO2-3 )and ion spectrum are clear and distinguishable.In conclusion,as the topographic slopes are 0°and 5°,spectrum curves of simultaneous ground-based natural test site spectral calibration ac-quired meet the requirements on ground spectra data which are required in atmospheric correction,spectral re-building and ground regression analysis.