Indirect orientation of CBERS Images: an assessment of techniques using straight lines and their combination with points

Abstract

The aim of this paper is to present and assess techniques for orientation of pushbroom sensors that allow the estimation of the polynomial coefficients describing the platform trajectory, using linear features and linear features combined with points as ground control. The pushbroom image acquisition is not
instantaneous and, as a consequence, six EOP (Exterior Orientation Parameters) for each scanned line must be estimated. The  sensor position and attitude parameters
are modeled with a time dependent polynomial. The proposed mathematic model is based on the equivalence property between planes, considering the pushbroom geometry. The relationship between object and image space is established through a mathematical model based on the equivalence between the vector normal to the projection plane in the image space and  to the vector normal to the rotated projection plane in the object space. The model based on collinearity equations
using points adapted to the pushbroom geometry was also implemented aiming at the comparison of the techniques, as well as to evaluate the use of control points and straight lines simultaneously. Some experiments using a CBERS scene were
accomplished in order to test the developed techniques. The obtained results showed that is possible estimate the EOP of pushbroom images using straight lines and that the combination of straight lines with points is a more flexible alternative
that allows good results.