Comment on gi-2022-3

Abstract

We propose a newly developed modular MObile LIdar SENsor System (MOLISENS) to enable new applications for automotive light detection and ranging (lidar) sensors independent of a complete vehicle setup. The stand-alone, modular setup supports both monitoring of dynamic processes and mobile mapping applications based on Simultaneous Localization and Mapping (SLAM) algorithms. The main objective of MOLISENS is to exploit newly emerging perception sensor technologies developed for the automotive industry for geoscientific applications. However, MOLISENS can also be used for other appli- cation areas, such as 3D mapping of buildings or vehicle independent data collection for sensor performance assessment and sensor modeling. Compared to Terrestrial Laser Scanners (TLSs), automotive lidar sensors provide advantages in terms of size (in the order of 10 cm), weight (in the order of 1 kg or less), price (typically between 5,000 EUR and 10,000 EUR), robustness (typical protection class of IP68), frame rates (typically 10 Hz–20 Hz), and eye safety of class (typically 1). For these reasons, automotive lidar systems can provide a very useful complement to currently used TLS systems that have their strengths in range and accuracy performance. The MOLISENS hardware setup consists of a sensor unit, a data logger, and a battery pack to support stand-alone and mobile applications. The sensor unit includes the automotive lidar Ouster OS1-64 Gen1, a ublox multi-band active Global Navigation Satellite System (GNSS) with the possibility for Real-Time Kinematic (RTK), and a 9-axis Xsens Inertial Measurement Unit (IMU). Special emphasis was put on the robustness of the individual components of MOLISENS to support operations in rough field and adverse weather conditions. The sensor unit has a standard screw for easy mounting on various platforms. The current setup of MOLISENS has a horizontal field of view of 360°, a vertical field of view with 45° opening angle, a range of 120 m, a spatial resolution of a few cm, and a temporal resolution of 10 Hz–20 Hz. To evaluate the performance of MOLISENS, we present a comparison between the integrated automotive lidar Ouster OS1-64 and the state of the art TLS RIEGL VZ-6000. The mobile mapping application of MOLISENS has been tested under various conditions and results are shown from two surveys in the Lurgrotte cave system in Austria and a glacier cave in Longyearbreen on Svalbard.