卫星振动频率和振幅对高光谱成像质量影响的仿真分析和实验研究

Simulation Analysis & Experimental Study of the Effects of Satellite Vibration Frequency and Amplitude on Hyperspectral Image

在星载推扫式高光谱成像仪成像过程中,卫星平台以振动为典型形式的姿态运动会导致探测器上不同的地物信息相互混叠,引起高光谱图像质量的退化。为了更有效地抑制、校正与补偿卫星振动引入的成像误差,针对典型色散型推扫成像光谱仪受平台振动而产生的空间维、光谱维质量退化的机理进行仿真分析和实验研究。通过分析其曝光时间内的光谱混合过程,得到了地物光谱和卫星姿态之间的关系,建立了推扫光谱成像退化模型。该模型综合考虑了不同姿态振动模式的影响,只要给出每个时刻的卫星平台姿态参数,即可通过普适的系数矩阵计算得出每个混合像元的平均混合比,进而获得仿真的退化高光谱数据立方体。详细推导了平均混合比的一般表达形式,对振幅、频率等振动参数对光谱混合的影响分别进行了定量分析。以实际运动状态下拍摄获得的高光谱数据立方体为例,进行了退化仿真和地面模拟运动退化实验,并对退化前后的高光谱数据进行了评价。结果表明,退化仿真和实际退化效果吻合,平均混合比能够直接反映高光谱图像退化的程度;卫星振动造成高光谱图像空间维质量恶化,使不同地物目标的光谱发生了混叠;高光谱数据的退化程度主要由振幅决定,振动频率对退化的影响较小。

In the imaging process of satellite-based pushbroom hyperspectral imager,attitude motions of satellite platform,represented by vibrations,will cause aliasing of the object information comes from different sub-areas of the detector,leading to degradation of hyperspectral image quality.In order to suppress and correct the imaging errors caused by satellite vibrations more effectively,spatial and spectral degradation mechanisms of typical dispersive pushbroom imaging spectrometer caused by satellite vibration are studied in this paper,including theoretical simulation and experimental study.With the analysis of spectral mixing process during exposure,the relationship between spectrum of ground object and satellite attitude is obtained,and a degradation model of pushbroom spectral imaging is presented.The effects of different attitudes of vibration are considered in the degradation model.Mean mixing ratios of each pixel are easy to calculate with a universal coefficient matrix,as long as the satellite attitude parameters of each moment are known.Then the simulation degraded spectral image data cube is achieved.The common expression of mean mixing ration is derived in detail.More important,the effects of vibration amplitude and frequency are quantitative analyzed separately.Degraded simulation and ground simulation experiments are carried out based on real hyperspectral data cubes,then the quality of the cubes before and after degradation are evaluated.Results show that simulation is in good agreement with reality.Mean mixing ratio can reflect the degradation extent of hyperspectral data directly.The satellite vibrations bring about spatial quality deteriorate of hyperspectral image,and lead to the aliasing of spectrum comes from different ground object.The degradation extent of hyperspectral data is determined mainly by vibration amplitude.The influence of frequency is limited.