A self-calibrating 3D ground-truth localization system using retroreflective landmarks

In this paper, we present an infrastructure-based ground-truth localization system suitable for deployment in large worksite environments. In particular, the system is low cost, simple-to-deploy, and is able to provide full six-degree of-freedom relative localization for three-dimensional laser scanners with centimetre-level accuracy in translation, and half degree accuracy in orientation. This system utilizes common laser scanner hardware, and exploits the fact that retroreflective material is easily identified based on the return intensity. This enables the use of simple rectangular signs placed around the scene as landmarks. An uncertainty model is presented that accounts for the shape of the landmarks, and a batch alignment algorithm is formulated that efficiently considers the structure of the problem. Lastly, characterization of the accuracy of the system is provided through small-scale testing in an indoor lab, and examples for a large-scale setup.