Robust and efficient multi-robot 3D mapping with octree based occupancy grids

A technique for merging 3D octree based occupancy grid maps robust to error in transformation between map reference frames is proposed and implemented. Recent robotics applications require 3D representations of the environments in which robots are to operate. In many cases, such as Simultaneous Localization and Mapping (SLAM) and when a large environment is required to be mapped within a reasonable time constraint, it is not feasible for a single robot to map the entire portion of the environment required to be mapped. In these cases it is necessary for a team of robots to build maps independently and merge them into a single global map. The contribution of this work lies in the introduction of methods which use map data from commonly mapped portions of the environment with registration techniques such that maps may still be merged coherently despite erroneous relative transformations between maps. The results from this paper demonstrate that not only are octree occupancy grids a suitable representation for multi-robot 3D mapping, but that the proposed techniques for improving erroneous transformation estimates between map frames are valid.