Back on Track: Bundle Adjustment for Dynamic Scene Reconstruction

Traditional SLAM systems, which rely on bundle adjustment, often struggle with highly dynamic scenes commonly found in casual videos. Such videos entangle the motion of dynamic elements, undermining the assumption of static environments required by traditional systems. Existing techniques either filter out dynamic elements or model their motion independently. However, the former often results in incomplete reconstructions, whereas the latter can lead to inconsistent motion estimates.This work proposes a novel approach that leverages a 3D point tracker to decouple the static and dynamic motion, effectively separating the camera-induced motion from the motion of dynamic objects.Bundle adjustment can therefore operate reliably considering only the camera-induced component of the observed motion. We further ensure depth consistency across video frames with lightweight post-processing based on scale maps.Our framework combines the core of traditional SLAM -- bundle adjustment -- with a robust learning-based 3D tracker front-end.By integrating motion decomposition, bundle adjustment, and depth refinement into a unified framework, our method accurately tracks the camera motion and produces temporally coherent and scale-consistent dense reconstructions, accommodating both static and dynamic elements. Our experiments on challenging datasets reveal significant improvements in camera pose estimation and 3D reconstruction accuracy.