I. Introduction
Mapping unknown environments is necessary for applications ranging from exploration to search and rescue, and has been a major focus of robotics research since 1980 [1]. While the methods vary, algorithms depend heavily on high quality sensor data to produce accurate maps [2]. Obtaining such data is difficult, as robots mapping unstructured environments depend on sophisticated locomotion mechanisms and multi-modal sensing. Furthermore, monitoring large dy-namic environments typically requires several robots to work in parallel. For example, recent research on mapping has involved quadrotors with multiple LiDARS, thermal cameras, and inertial sensors, as well as ground robots with RGB-D cameras and 2D laser scanners [3]–[7].