Observation and understanding of the world through digital sensors is an ever-increasing part of modern life. Systems of multiple sensors acting together have far-reaching applications in automation, entertainment, surveillance, remote machine control, and robotic self-navigation. Recent developments in digital camera, range sensor and immersive display technologies enable the combination of augmented reality and telepresence into Augmented Telepresence, which promises to enable more effective and immersive forms of interaction with remote environments.
The purpose of this work is to gain a more comprehensive understanding of how multi-sensor systems lead to Augmented Telepresence, and how Augmented Telepresence can be utilized for industry-related applications. On the one hand, the conducted research is focused on the technological aspects of multi-camera capture, rendering, and end-to-end systems that enable Augmented Telepresence. On the other hand, the research also considers the user experience aspects of Augmented Telepresence, to obtain a more comprehensive perspective on the application and design of Augmented Telepresence solutions.
This work addresses multi-sensor system design for Augmented Telepresence regarding four specific aspects ranging from sensor setup for effective capture to the rendering of outputs for Augmented Telepresence. More specifically, the following problems are investigated: 1) whether multi-camera calibration methods can reliably estimate the true camera parameters; 2) what the consequences are of synchronization errors in a multi-camera system; 3) how to design a scalable multi-camera system for low-latency, real-time applications; and 4) how to enable Augmented Telepresence from multi-sensor systems for mining, without prior data capture or conditioning.
The first problem was solved by conducting a comparative assessment of widely available multi-camera calibration methods. A special dataset was recorded, enforcing known constraints on camera ground-truth parameters to use as a reference for calibration estimates. The second problem was addressed by introducing a depth uncertainty model that links the pinhole camera model and synchronization error to the geometric error in the 3D projections of recorded data. The third problem was addressed empirically - by constructing a multi-camera system based on off-the-shelf hardware and a modular software framework. The fourth problem was addressed by proposing a processing pipeline of an augmented remote operation system for augmented and novel view rendering.
The calibration assessment revealed that target-based and certain target-less calibration methods are relatively similar in their estimations of the true camera parameters, with one specific exception. For high-accuracy scenarios, even commonly used target-based calibration approaches are not sufficiently accurate with respect to the ground truth. The proposed depth uncertainty model was used to show that converged multi-camera arrays are less sensitive to synchronization errors. The mean depth uncertainty of a camera system correlates to the rendered result in depth-based reprojection as long as the camera calibration matrices are accurate. The presented multi-camera system demonstrates a flexible, de-centralized framework where data processing is possible in the camera, in the cloud, and on the data consumer's side. The multi-camera system is able to act as a capture testbed and as a component in end-to-end communication systems, because of the general-purpose computing and network connectivity support coupled with a segmented software framework. This system forms the foundation for the augmented remote operation system, which demonstrates the feasibility of real-time view generation by employing on-the-fly lidar de-noising and sparse depth upscaling for novel and augmented view synthesis.
In addition to the aforementioned technical investigations, this work also addresses the user experience impacts of Augmented Telepresence. The following two questions were investigated: 1) What is the impact of camera-based viewing position in Augmented Telepresence? 2) What is the impact of depth-aiding augmentations in Augmented Telepresence? Both are addressed through a quality of experience study with non-expert participants, using a custom Augmented Telepresence test system for a task-based experiment. The experiment design combines in-view augmentation, camera view selection, and stereoscopic augmented scene presentation via a head-mounted display to investigate both the independent factors and their joint interaction.
The results indicate that between the two factors, view position has a stronger influence on user experience. Task performance and quality of experience were significantly decreased by viewing positions that force users to rely on stereoscopic depth perception. However, position-assisting view augmentations can mitigate the negative effect of sub-optimal viewing positions; the extent of such mitigation is subject to the augmentation design and appearance.
In aggregate, the works presented in this dissertation cover a broad view of Augmented Telepresence. The individual solutions contribute general insights into Augmented Telepresence system design, complement gaps in the current discourse of specific areas, and provide tools for solving challenges found in enabling the capture, processing, and rendering in real-time-oriented end-to-end systems.