Abstract

We propose a direct (feature-less) monocular SLAM algo- rithm which, in contrast to current state-of-the-art regarding direct meth- ods, allows to build large-scale, consistent maps of the environment. Along with highly accurate pose estimation based on direct image align- ment, the 3D environment is reconstructed in real-time as pose-graph of keyframes with associated semi-dense depth maps. These are obtained by filtering over a large number of pixelwise small-baseline stereo compar- isons. The explicitly scale-drift aware formulation allows the approach to operate on challenging sequences including large variations in scene scale. Ma jor enablers are two key novelties: (1) a novel direct tracking method which operates on sim(3), thereby explicitly detecting scale-drift, and (2) an elegant probabilistic solution to include the effect of noisy depth values into tracking. The resulting direct monocular SLAM system runs in real-time on a CPU.