Monocular 3D Exploration using Lines-of-Sight and Local Maps

Abstract

Nowadays, robots equipped with a single camera, such as micro aerial vehicles (MAVs), are easily found at affordable costs. They can be used in different tasks, including the building of 3D environment maps. For building such maps, monocular simultaneous localization and mapping (SLAM) methods are employed, which usually generate sparse or semi-dense representations that are ill-suited for navigation tasks. We propose a new 3D exploration approach that uses a monocular camera as the only source of information. Our approach transforms a point cloud generated by monocular SLAM into local volumetric maps. These maps are built using the lines-of-sight between points and keyframes, allowing the MAV to navigate safely through the environment. Goal poses are dynamically defined to guide the MAV to explore the environment while avoiding obstacles. Besides that, the proposed approach seeks to determine properly when the environment was entirely explored, preventing that MAV stops before cover all the environment or flies more that is needed. The effectiveness of the proposed approach is evaluated in experiments in two different indoor environments, and show that it is possible to explore an environment using only a MAV equipped with a single monocular camera.