Pulse Based Time-of-Flight Range Sensing

Abstract

Pulse-based Time-of-Flight (PB-ToF) cameras are an attractive alternative range imaging approach, compared to the widely commercialized Amplitude Modulated Continuous-Wave Time-of-Flight (AMCW-ToF) approach. This paper presents an in-depth evaluation of a PB-ToF camera prototype based on the Hamamatsu area sensor S11963-01CR. We evaluate different ToF-related effects, i.e., temperature drift, systematic error, depth inhomogeneity, multi-path effects, and motion artefacts. Furthermore, we evaluate the systematic error of the system in more detail, and introduce novel concepts to improve the quality of range measurements by modifying the mode of operation of the PB-ToF camera. Finally, we describe the means of measuring the gate response of the PB-ToF sensor and using this information for PB-ToF sensor simulation.

An Overview of Lidar Imaging Systems for Autonomous Vehicles

“…Since the speed of light is a given constant while we stay within the same optical medium, the distance to the object is directly proportional to the traveled time. The measured time is obviously representative of twice the distance to the object, as light travels to the target forth and back, and, therefore, must be halved to give the actual range value to the target [13,18,19]:…”

“…For the sake of brevity, they will only be cited so the reader is referred to the linked references. For example, phase measurement may be obtained via signal processing techniques using mixers and low-pass filters [28], or, more generally, by cross-correlation of the sampled signal backscattered at the target with the original modulated signal shifted by a number (typically four) of fixed phase offsets [13,19,29,30]. Another common approach is to sample the received modulated signal and mix it with the reference signal, to then sample the resultant signal at four different phases [31].…”

Accuracy–Power Controllable LiDAR Sensor System with 3D Object Recognition for Autonomous Vehicle

“…Among the sensors that provide safety and convenience, light detection and ranging (LiDAR) sensors are the most essential for autonomous vehicles because they measure the distance between a vehicle and an object and recognize the object [ 6 , 7 ]. As shown in Figure 1 , a typical LiDAR sensor using a laser in 905 nm of the near-infrared ray (NIR) region uses technology to convert the time-of-flight (ToF), which is the time difference between the transmission of the laser ( ) and its reflection from an object back to the sensor ( ) [ 8 , 9 , 10 , 11 ].…”

A Comparison of Low-Cost Sensor Systems in Automatic Cloud-Based Indoor 3D Modeling

“…RGB-D cameras provide a more affordable and lightweight type of range sensor compared to a TLS, and provide reasonably accurate results in comparison to them, though their range is shorter [13]. Depth information can be collected using active stereo, projecting an infrared pattern on the scene to calculate depth [14], or, less commonly, using a time-of-flight approach [8], which can further be divided into phase-shift [14] and pulse-based sensing [15]. RGB-D cameras, combining images with depth information, add textures to the geometry without a need for key points as in photogrammetry [16].…”

“…RGB-D cameras, combining images with depth information, add textures to the geometry without a need for key points as in photogrammetry [16]. While active stereo and time-of-flight are commonly used for the collection of depth information, pulse-based sensing has only recently seen use in RGB-D cameras [15]. RGB-D cameras see indoor use for positioning [17], as well as for mapping and modeling [9,18].…”