| The modulation transfer function and ground pixel resolution are important parameters for evaluating the image quality of optical remote sensing satellites,which are related to the quality of satellite remote sensing data and the breadth and depth of quantitative applications.With the continuous emergence and rapid development of high-resolution remote sensing satellites(or constellations),the requirements for their image quality evaluation are also increasing.The array point sources system can achieve remote control and automatic operation in unmanned working mode.Combined with data processing software for point source images,it can achieve high-precision,commercial,high-frequency automatic calibration and image quality evaluation of optical remote sensing satellites(or constellations).The network architecture of the array point sources system is mainly composed of a point sources array,a server,and a remote PC.According to the remote communication requirements of the system,the custom data exchange communication protocol and communication architecture based on multi-threaded network programming technology are designed.Using Spring Boot software development framework and MyBatis persistence layer framework,the remote control and application software of the array point sources system is developed to realize the decentralized control and centralized management of the array point sources system by the client.The automatic calibration model of the array point sources system was studied,and an automatic data acquisition scheme with uniform distribution in time and space was designed.Combined with the automatic tracking and observation of the sun’s motion trajectory,the high-precision calibration of the array point sources is realized.The experimental verification results show that the pointing accuracy of array point sources system is better than 0.1 °,and they have high-precision spatial pointing control functions.According to the satellite observation vector obtained by the orbit forecast and the sun vector at the time of the satellite topping,the array point sources system realizes the high-precision spatial pointing by combining the mirror reflection theorem and the system calibration model,which is convenient for optical remote sensing satellites to accurately observe and image the point sources system.The image quality evaluation method for optical remote sensing satellites based on array point sources uses an automated point sources array as the detection reference target,uses a two-dimensional Gaussian model to fit the array point sources image to obtain the image coordinates,and combines ground point source position measurement to obtain the ground pixel resolution of the remote sensor.With the point coordinates of the point source image as the benchmark,the array point source remote sensing image data is position registered and fitted with a two-dimensional Gaussian model to obtain the point spread function and modulation transfer function values of the imaging system.The experimental results show that the collinear error of the pixel coordinates is less than 0.002 pixels,and the relative deviation of ground pixel resolution is better than 6.5‰. |
