Combined Ridge-stein Estimator in Exterior Orientation for Linear Pushbroom Imagery

The paper presents the combined ridge-stein estimator (CRS) for linear pushbroom imagery exterior orientation, which is severely ill-conditioned for the strong correlation among exterior orientation elements of linear pushbroom imagery. The estimator is a new biased method combining the ridge estimator and the stein estimator. It can effectively change the ill-conditioned state of linear pushbroom imagery exterior orientation process and achieve optimum estimation values through applying different scale compression to each least squares estimation component. Its performance is evaluated using one 10-meter SPOT 1 panchromatic image and one 2.5-meter SPOT 5 panchromatic image. Experimental results show that the combined ridge-stein estimator can effectively overcome the strong correlation among exterior orientation elements and reach high reliability, stability and accuracy. It is within one pixel accurate for ground directional points and within one and a half pixels accurate for ground check points.