To mitigate the detrimental effects of sporadic artifacts (e.g., swallowing) on motion parameter estimation, translation estimates were filtered with a 5-point median filter and then re-applied (using 3dAllineate in AFNI [ Cox, 1996 ]) to the original data before motion correction.
The " " symbols denote the estimated translation, which is the peak location on the POC surface.
We simultaneously estimated translation parameters for the north, east, and vertical components in the displacement data.
Most of the existing algorithms fall into the first category because the translation is the most commonly encountered motion and the complexity of estimating translation parameters is relatively low for real-time stabilization.
Although the estimated translation component (Additional file 2: Table S2) can be interpreted as instability of the reference station or large-scale deformation affecting the whole observation network, the horizontal components in the 2nd and the 4th years are larger than those in other periods.
The relative error is calculated for the initial set of 3D 2D correspondences by re-projecting 3D points using the estimated translation and rotation for the camera, while the true re-projection error is calculated using ground truth, obtained from the knowledge that the camera is stationary.
Estimated translation and rotation parameters never exceeded 3 mm.
Estimated translation and rotation parameters were inspected and never exceeded 3 mm.
Estimated translation and rotation parameters were inspected and never exceeded 3 mm per run.
Head motion was restricted with foam padding and straps over the forehead and under the chin (estimated translation and rotation parameters were inspected and never exceeded 2 mm or 2°).
