Whelan, Thomas J. (2014) Real-time Dense Simultaneous Localisation and Mapping over Large Scale Environments. PhD thesis, National University of Ireland Maynooth.
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Abstract
The ability for a robot to create a map of an unknown environment and
localise within that map is of critical importance in intelligent autonomous
operation. This problem is referred to as Simultaneous Localisation and
Mapping (or SLAM) and has been one of the major focusses of robotics
research over the past 25 years. Although the initial focus was on 2D
laser scan SLAM, more recently full 3D SLAM has become the dominant
paradigm.
The recent expansion in popularity of full, dense 3D SLAM is arguably
a result of the release of the Microsoft Kinect commodity RGB-D sensor,
which provides high quality depth sensing capabilities for a little over one
hundred US dollars. Before the advent of the Kinect, 3D SLAM methods
required either time of flight (TOF) sensors, 3D lidar scanners or stereo
vision, which were typically either quite expensive or not suitable for fully
mobile real-time operation if dense reconstruction was desired. Another
recent technology which is often coupled with dense methods is General-
Purpose computing on Graphics Processing Units (GPGPU) which exploits
the massive parallelism available in GPU hardware to perform high
speed and often real-time processing on entire images every frame. Being
an affordable commodity technology, GPU-based programming is arguably
another large enabler in recent dense SLAM research.
Many visual SLAM systems and 3D reconstruction systems (both offline
and online) have been published in recent times that rely purely on RGBD
sensing capabilities because of the Kinect’s low price and accuracy;
[43, 26, 113, 86]. However given the density of the data available, many
existing systems have one or many limitations imposed by the challenges of
processing such large amounts of information. These include a limitation
in operating area, the inability to function in real-time over large scales, or
not producing a globally consistent reconstruction of the explored environment
or a map representation which is meaningful for robotic operations.
In this thesis we address these issues through the development of a system
which allows real-time globally consistent dense mapping over large scales,
while providing a map representation which is useful for both autonomous
robot navigation and higher level functionality such as object detection.
The development of this system involves solving a number of critical issues
including efficient real-time dense mapping over large scales, robust
real-time camera pose estimation, a scalable means of correcting dense reconstructions
for global consistency and representing the map in a format
suitable for robotic operations. We address these issues respectively by 1)
employing an efficient rolling cyclical buffer representation for mapping in
the local frame; 2) estimating a dense photometric camera pose constraint
in conjunction with a dense geometric constraint and jointly optimising
for a camera pose estimate; 3) optimising the dense map by means of a
non-rigid space deformation parameterised by a loop closure constraint;
and, 4) intelligently simplifying the dense map reconstruction to a planar
representation.
As part of this the system is implemented as a set of hierarchical multithreaded
components which are capable of operating in real-time. The
architecture facilitates the creation and integration of new modules with
minimal impact on the performance of the overall system. This yields
an adaptable and easily extendable system which is easily combined with
other software systems designed for related operations.
We provide a comprehensive quantitative and qualitative evaluation of
all aspects of the system’s performance, demonstrating real-time dense
SLAM over large scales. Our evaluation includes comparisons to other
approaches on standard benchmarks in terms of computational performance,
trajectory estimation and surface reconstruction quality.
Item Type: | Thesis (PhD) |
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Keywords: | Real-time; Dense Simultaneous Localisation; Mapping; Large Scale Environments; |
Academic Unit: | Faculty of Science and Engineering > Computer Science |
Item ID: | 5801 |
Depositing User: | IR eTheses |
Date Deposited: | 10 Feb 2015 10:32 |
URI: | https://mural.maynoothuniversity.ie/id/eprint/5801 |
Use Licence: | This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here |
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