Triangle mesh maps have proven to be a versatile 3D environment
representation for robots to navigate in challenging indoor and outdoor
environments exhibiting tunnels, hills and varying slopes. To make use of these
mesh maps, methods are needed that allow robots to accurately localize
themselves to perform typical tasks like path planning and navigation. We
present Mesh ICP Localization (MICP-L), a novel and computationally efficient
method for registering one or more range sensors to a triangle mesh map to
continuously localize a robot in 6D, even in GPS-denied environments. We
accelerate the computation of ray casting correspondences (RCC) between range
sensors and mesh maps by supporting different parallel computing devices like
multicore CPUs, GPUs and the latest NVIDIA RTX hardware. By additionally
transforming the covariance computation into a reduction operation, we can
optimize the initial guessed poses in parallel on CPUs or GPUs, making our
implementation applicable in real-time on a variety of target architectures. We
demonstrate the robustness of our localization approach with datasets from
agriculture, drones, and automotive domains