Rumination Meets VSLAM: You Do Not Need to Build All the Submaps in Realtime

In the application of visual navigation, submap-based visual simultaneous localization and mapping (VSLAM) has become one of the most robust monocular solutions in recent years, which is able to resume tracking by multisubmap maintenance and merging. However, due to the lack of long-term data association between submaps, global consistency cannot be guaranteed in the existing work, especially in situations without loop-closure. Considering the fact that not all the submap have to be built in realtime, we propose a VSLAM system with realtime and nonrealtime hybrid style, RUMI-SLAM. Inspired by the rumination of mammalians that processes food in various stomaches and absorbs it in one stomach, RUMI-SLAM performs asynchronous submap building and centralized submap management. Building additional submaps in parallel leads to enriched mapping elements and enhanced data association across submaps. The experimental results demonstrate the superiority of RUMI-SLAM over the existing VSLAM systems, especially the robustness to challenging situations. We also provide real-robot experiments to demonstrate our RUMI-SLAM in the application of visual navigation. Our study provides a novel asynchronous submap-based VSLAM framework, which achieves globally consistent submap merging without the requirement of loop-closure.