Accurate outdoor ground truth based on total stations

TL;DR

This paper introduces a total station-based system for precise outdoor vehicle ground truth measurement, achieving 10 mm and 0.6 deg accuracy, outperforming RTK especially in GNSS-challenged environments.

Contribution

It presents a novel six DOF total station system for outdoor ground truth, enhancing accuracy over traditional three DOF methods and comparing favorably with RTK.

Findings

Achieves an average positional error of 10 mm.

Attains an average orientation error of 0.6 degrees.

Outperforms RTK in environments with weak GNSS signals.

Abstract

In robotics, accurate ground-truth position fostered the development of mapping and localization algorithms through the creation of cornerstone datasets. In outdoor environments and over long distances, total stations are the most accurate and precise measurement instruments for this purpose. Most total station-based systems in the literature are limited to three Degrees Of Freedoms (DOFs), due to the use of a single-prism tracking approach. In this paper, we present preliminary work on measuring a full pose of a vehicle, bringing the referencing system to six DOFs. Three total stations are used to track in real time three prisms attached to a target platform. We describe the structure of the referencing system and the protocol for acquiring the ground truth with this system. We evaluated its precision in a variety of different outdoor environments, ranging from open-sky to forest trails, and compare this system with another popular source of reference position, the Real Time Kinematics (RTK) positioning solution. Results show that our approach is the most precise, reaching an average positional error of 10 mm and 0.6 deg. This difference in performance was particularly stark in environments where Global Navigation Satellite System (GNSS) signals can be weaker due to overreaching vegetation.