The Effect Analysis And Simulation Of Platform Motion On Image Quality Of Spaceborn TDICCD Camera

Satellite motion is one of the important factors influencing image quality of high resolution remote sensing cameras and it disturbs normal image motion and causes abnormal image motion which degrades image quality. Motion degradation of a TDICCD camera is different from those of a staring camera and a normal linear push-broom camera. Researches on influence of platform motion on image quality of spaceborn TDICCD camera and simulation of dynamic imaging are significant to improve image quality of camera. They can not only provide references to choose applicable image motion compensation algorithm and to raise appropriate index of satellite control system but also be helpful to complete simulation of the overall image chain. The detailed work is as follows:First of all, mechanism of motion degradation based on Line Spread Function theory was analyzed and then a mathematical model of degradation of image quality caused by image motion was established according to operating principle of TDICCD. Based on this model, LSFs for image motion of different types and directions and strict expressions of MTF for abnormal linear image motion were deduced. Geometric distortion was evaluated by the linear part of the PTF. A method of numerical integration to calculate dynamic MTF was put forward and MTF for sinusoidal image vibration was calculated through this method. Geometric distortion and image blur caused by image motion were analyzed based on the above-mentioned results and methods. The analyses show that motion degradation of TDICCD camera is space-variant and image blur and geometric distortion cause by abnormal image motion of different types and directions are quite different.Secondly, several coordinate systems were defined and mapping relationship between the object and image was established by transformation of coordinate systems and thus model of image motion calculation was obtained. And then based on this model and motion degradation model of TDICCD, influences on image quality of factors such as self-rotation of the earth, control error of satellite including pointing error and attitude stability, error of orbit height and orbit inclining were analyzed. Abnormal image motion caused by platform motion can be calculated by model of image motion calculation, which provides basis for dynamic imaging simulation of TDICCD.At last, simulation method of dynamic imaging of TDICCD according to the imaging principle of sampling imaging system was brought forward. Means of numerical integration and pixel interpolation combining with principle of summing of charge were applied to simulate image degradation caused by different motion errors. MSE and SSIM were adopted to evaluate quality of simulated images. Anlyses show that digital simulation results coincide with theoretical results.