Variation of Camera Parameters due to Common Physical Changes in Focal Length and Camera Pose

TL;DR

This paper investigates how common physical changes like focal length and camera pose affect camera parameters, revealing distinct variation trends and validating findings through reprojection error comparisons.

Contribution

It demonstrates that variations in camera parameters due to physical changes can be characterized and distinguished, providing new insights into camera calibration behavior.

Findings

Focal length variations cause different principal point deviations across camera types.

Camera pose changes lead to similar deviation trends likely aligned with gravity.

Reprojection errors confirm the validity of the identified variation patterns.

Abstract

Accurate calibration of camera intrinsic parameters is crucial to various computer vision-based applications in the fields of intelligent systems, autonomous vehicles, etc. However, existing calibration schemes are incompetent for finding general trend of the variation of camera parameters due to common physical changes. In this paper, it is demonstrated that major and minor variations due to changes in focal length and camera pose, respectively, can be identified with a recently proposed calibration method. It is readily observable from the experimental results that the former variations have different trends (directions) of principal point deviation for different types of camera, possibly due to different internal lens configurations, while the latter have very similar trends in the deviation which is most likely due to direction of gravity. Finally, to confirm the validity of such unprecedented findings, 3D to 2D reprojection errors are compared for different methods of camera calibration.