Comparison between MATLAB bundle adjustment function and parallax bundle adjustment

Bundle Adjustment (BA) takes a crucial part in Structure from Motion (SfM) which refines a visual reconstruction by optimizing the camera poses and feature positions. The performance of BA can differ depending on the parametrization methods. This paper evaluates two bundle adjustment techniques using standard BA function from MATLAB and Parallax BA. The two BA techniques are compared using data from the 'Starry Night' and 'MALAGA Parking-6L' with different initial inputs. The accuracy and convergence properties of the two BA methods have been evaluated. The effect of the different parameterization techniques and initial information was also analyzed. In most cases, the results of Parallax BA show better accuracy with lower final reprojection error and are less sensitive to the initialization values. It is evaluated that the parallax angle avoids the singularity issue commonly found in Standard BA, which shows that Parallax BA outperforms Standard BA. Furthermore, visual-inertial SLAM (VI-SLAM), based on Parallax BA, has been presented. It is much more reliable than a pure-vision system, showing further improved performance in terms of robustness and accuracy, even with less feature observation. The open-source code can be found in: https://github.com/uts-hb/ParallaxBA.git