Abstract
Owing to the dynamic imaging system, the trajectory model plays a very important role in the geometric processing of high resolution satellite imagery. However, establishing a trajectory model is difficult when only discrete and noisy data are available. In this manuscript, we proposed a general robust trajectory model, the penalized spline model, which could fit trajectory data well and smooth noise. The penalized parameter λ controlling the smooth and fitting accuracy could be estimated by generalized cross-validation. Five other trajectory models, including third-order polynomials, Chebyshev polynomials, linear interpolation, Lagrange interpolation and cubic spline, are compared with the penalized spline model. Both the sophisticated ephemeris and on-board ephemeris are used to compare the orbit models. The penalized spline model could smooth part of noise, and accuracy would decrease as the orbit length increases. The band-to-band misregistration of ZiYuan-3 Dengfeng and Faizabad multispectral images is used to evaluate the proposed method. With the Dengfeng dataset, the third-order polynomials and Chebyshev approximation could not model the oscillation, and introduce misregistration of 0.57 pixels misregistration in across-track direction and 0.33 pixels in along-track direction. With the Faizabad dataset, the linear interpolation, Lagrange interpolation and cubic spline model suffer from noise, introducing larger misregistration than the approximation models. Experimental results suggest the penalized spline model could model the oscillation and smooth noise.
Highlights
Different from frame cameras, dynamic imaging system utilizes the relative movement between cameras and targets to capture two dimensional (2D) images
We proposed the penalized spline model, a robust trajectory model, for ZY3 satellite, which could model the oscillation and overcome noises
The balance between the fitting accuracy and noise smoothing is controlled by a penalty parameter λ, which is estimated via the generalized cross-validation
Summary
Different from frame cameras, dynamic imaging system utilizes the relative movement between cameras and targets to capture two dimensional (2D) images. The trajectory model of linear pushbroom cameras, like ZY3, describes satellite movements by attitude and orbit models. Some use the attitude data and ephemeris data as the initial value of the simplified models, which usually assume the trajectory model is stable and could be modelled with no more than 3rd polynomials or twobody motion model. This hypothesis is sensible when the accuracy of attitude and orbit data are limited. Some others assume that the attitude data and ephemeris data are with sufficient accuracy, so only compensation models are required to compensate the errors of trajectory models. Given that its accuracy is limited by the accuracy of attitude, the band-toband registration (BBR) is used to compare the attitude models
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