基于辐射状靶标的高分辨率光学卫星传感器像质评价方法研究

Image-Quality Evaluation of High-Spatial-Resolution Satellite Optical Sensor Based on Radial Target

空间分辨率与调制传递函数(MTF)是高分辨率光学卫星传感器像质评价的重要参数,直接客观反映遥感器成像系统的成像质量。针对空间分辨率检测的辐射状靶标,提出一种与相同反射率大面积靶标相结合的方法,依据靶标调制度、传感器入瞳的物方调制度与像方调制度之间的关系,准确获取不含大气的星载遥感器成像系统在轨MTF与大气MTF值。实验结果表明:采用辐射状靶标法可同时获取星载遥感器成像系统空间分辨率与在轨MTF值,实时的大气MTF值为0.7519,基于辐射状靶标的在轨MTF检测结果与刃边法在轨MTF检测结果差异小于5%,该方法可用于实现高分辨率光学卫星传感器在轨像质评价。

The spatial resolution and modulation transfer function(MTF)are important parameters for image-quality evaluation of high-spatial-resolution satellite optical sensors.They objectively reflect the imaging quality of a remote-sensing imaging system.We present a method using a radial target for spatial-resolution measurement that employs a large-area target with uniform reflectivity.This method depends on the relationship between the target modulation degree,object modulation degree,and image modulation degree in the pupil of the sensor.It can accurately determine the on-orbit MTF value of a spaceborne remote-sensing imaging system without atmospheric effects as well as the MTF value of the atmosphere.Experimental results show that the proposed radial-target method can simultaneously determine the spatial resolution and the on-orbit MTF value of the spaceborne remote-sensing imaging system.The real-time MTF value of the atmosphere is 0.7519.The difference between the on-orbit MTF value measured by our radial-target method and that measured by the knife-edge method is less than 5%.The proposed method can provide on-orbit image-quality evaluation of high-spatial-resolution satellite optical sensors.