Spatial augmented reality is a particular kind of augmented reality technique that uses projector to blend the real objects with virtual contents. Coincidentally, as a means of 3D shape measurement, structured light illumination makes use of projector as part of its system as well. It uses the projector to generate important clues to establish the correspondence between the 2D image coordinate system and the 3D world coordinate system. So it is appealing to build a system that can carry out the functionalities of both spatial augmented reality and structured light illumination. In this dissertation, we present all the hardware platforms we developed and their related applications in spatial augmented reality and structured light illumination. Firstly, it is a dual-projector structured light 3D scanning system that has two synchronized projectors operate simultaneously, consequently it outperforms the traditional structured light 3D scanning system which only include one projector in terms of the quality of 3D reconstructions. Secondly, we introduce a modified dual-projector structured light 3D scanning system aiming at detecting and solving the multi-path interference. Thirdly, we propose an augmented reality face paint system which detects human face in a scene and paints the face with any favorite colors by projection. Additionally, the system incorporates a second camera to realize the 3D space position tracking by exploiting the principle of structured light illumination. At last, a structured light 3D scanning system with its own built-in machine vision camera is presented as the future work. So far the standalone camera has been completed from the a bare CMOS sensor. With this customized camera, we can achieve high dynamic range imaging and better synchronization between the camera and projector. But the full-blown system that includes HDMI transmitter, structured light pattern generator and synchronization logic has yet to be done due to the lack of a well designed high speed PCB.

3D face modeling is currently a popular area in Computer Graphics and Computer Vision. Many techniques have been introduced for this purpose, such as using one or more cameras, 3D scanners, and many other systems of sophisticated hardware with related software. But the main goal is to find a good balance between visual reality and the cost of the system. In this thesis, reconstruction of a 3D human face from a pair of stereo cameras is studied. Unlike many other systems, facial feature points are obtained automatically from two photographs with the help of a dot pattern projected on the object&amp / #8217 / s face. It is seen that using projection pattern also provided enough feature points to derive 3D face roughly. These points are then used to fit a generic face mesh for a more realistic model. To cover this 3D model, a single texture image is generated from the initial stereo photographs.

Nowadays, 3D modelling of objects from multiple images is a topic that has gained great recognition and is widely used in various fields. Recently, lots of progress has been made in identification of people using 3D face models, which are usually reconstructed from multiple face images. In this thesis, a system including stereo cameras and structured light is built for the purpose of 3D modelling. The system outputs are 3D shapes of the face and also the texture information registered to this shape. Although the system in this thesis is developed for face reconstruction, it is not specific to faces. Using the same methodology proposed in this study 3D reconstruction of any object can be achieved.

An approach to quantitatively determine patient surface contours as part of an augmented reality (AR) system for patient position and posture correction was developed. Quantitative evaluation of the accuracy of patient positioning and posture correction requires the knowledge of coordinates of the patient contour. The system developed uses the surface contours from the planning CT data as the reference surface coordinates. The corresponding reference point cloud is displayed on screen to enable AR assisted patient positioning. A 3D computer vision system using structured light then captures the current 3D surface of the patient. The offset between the acquired surface and the reference surface, representing the desired patient position, is the alignment error. Two codification strategies, spatial encoding, and temporal encoding, were examined. Spatial encoding methods require a single static pattern to work, thus enabling dynamic scenes to be captured. Temporal encoding methods require a set of patterns to be successively projected onto the object, the encoding for each pixel is only complete when the entire series of patterns has been projected. The system was tested on a camera tracking object. The structured light reconstruction was accurate to within ±1 mm, ±1.5 mm, and ±4 mm in x, y, and z-directions (camera optical axis) respectively. The method was integrated into a simplified AR system and a visualization scheme based on z-direction offset was developed. A demonstration of how the final AR-3D vision hybrid system can be used in a clinical situation was given using an anatomical teaching phantom. The system and visualisation worked well and demonstrated the proof of principal of the approach. It was found that the achieved accuracy was not yet sufficient for clinical use. Further work on improving the projector calibration accuracy is required. Both the camera registration process and 3D computer vision using structured light have been shown to be capable of sub-millimeter accuracy on their own. If that level of accuracy can be reproduced in this system, the concept presented can potentially be used in Oncology departments as a cost-effective patient setup guidance system for external beam radiotherapy, used in addition to current laser/portal imaging/cone beam CT based setup procedures.

The use of structured light illumination techniques for three-dimensional data acquisition is, in many cases, limited to stationary subjects due to the multiple pattern projections needed for depth analysis. Traditional Composite Pattern (CP) multiplexing utilizes sinusoidal modulation of individual projection patterns to allow numerous patterns to be combined into a single image. However, due to demodulation artifacts, it is often difficult to accurately recover the subject surface contour information. On the other hand, if one were to project an image consisting of many thin, identical stripes onto the surface, one could, by isolating each stripe center, recreate a very accurate representation of surface contour. But in this case, recovery of depth information via triangulation would be quite difficult. The method described herein, Modified Composite Pattern (MCP), is a conjunction of these two concepts. Combining a traditional Composite Pattern multiplexed projection image with a pattern of thin stripes allows for accurate surface representation combined with non-ambiguous identification of projection pattern elements. In this way, it is possible to recover surface depth characteristics using only a single structured light projection. The technique described utilizes a binary structured light projection sequence (consisting of four unique images) modulated according to Composite Pattern methodology. A stripe pattern overlay is then applied to the pattern. Upon projection and imaging of the subject surface, the stripe pattern is isolated, and the composite pattern information demodulated and recovered, allowing for 3D surface representation. In this research, the MCP technique is considered specifically in the context of a Hidden Markov Process Model. Updated processing methodologies explained herein make use of the Viterbi algorithm for the purpose of optimal analysis of MCP encoded images. Additionally, we techniques are introduced which, when implemented, allow fully automated processing of the Modified Composite Pattern image.

Fingerprints are the most accurate and widely used biometrics for human identification due to their uniqueness, rapid and easy means of acquisition. Contact based techniques of fingerprint acquisition like traditional ink and live scan methods are not user friendly, reduce capture area and cause deformation of fingerprint features. Also, improper skin conditions and worn friction ridges lead to poor quality fingerprints. A non-contact, high resolution, high speed scanning system has been developed to acquire a 3D scan of a finger using structured light illumination technique. The 3D scanner system consists of three cameras and a projector, with each camera producing a 3D scan of the finger. By merging the 3D scans obtained from the three cameras a nail to nail fingerprint scan is obtained. However, the scans from the cameras do not merge perfectly. The main objective of this thesis is to calibrate the system well such that 3D scans obtained from the three cameras merge or align automatically. This error in merging is reduced by compensating for radial distortion present in the projector of the scanner system. The error in merging after radial distortion correction is then measured using the projector coordinates of the scanner system.

The health and productive output of dairy cows can be closely correlated to individual cow feed intake. Being able to monitor feed intake on a daily basis is beneficial dairy farm management. Each cow can be addressed individually with minimal time required from those working with the animals. This is essential as time management is closely tied to resource management in a dairy operation. Anything that can save time and resources and increase profitability and herd health is a paramount advantage in dairy farming. This study examined the use of machine vision structured light illumination three-dimensional scanning of cow feed to determine the volume and weight of feed in a bin before and after feeding dairy cow. Calibration and control tests were conducted to determine the effectiveness and capability of implementing such a machine vision feed scanning system. Such a system is ideal as it does not obstruct workflow or cow feeding behavior. This is an improvement over existing systems as the system in this research study can be implemented into existing farm operations with minimal effort and costs.

Colloidal particles are small particles ranging in size from nanometres to micrometres suspended in a fluid. Amongst many scientific and biological applications, they have been used to model crystallisation, vitrification, and particle interactions along with the use of colloidal model systems for the study of the fundamental nature of the fluid-crystal and fluid-glass phase transitions. It has been shown that colloidal particles can be trapped and manipulated using strongly-focused light beams known as optical tweezers, and this has paved the way for research into the area of micromanipulation using optical trapping. Holographic elements can replace multiple lenses in creating large numbers of optical tweezers and this is known as holographic optical trapping (HOT). A computer generated hologram can be designed to create large structured light fields, consisting of multiple foci, to enable trapping of multiple particles in arbitrary configurations. The overall aim of this project was to design, develop and test the suitability of a simple, inexpensive optical trapping arrangement suitable for multiple optical trapping. To achieve this, a theoretically-exact expression for the wavefront of a single point source was implemented in the coding scheme, allowing for the fast creation of multiple point sources suitable for holographic optical trapping experiments. Compensation for the spherical aberration present in the focusing optics was implemented into the coding scheme. Kodalith photographic film was chosen as the holographic recording medium for its high contrast and availability. The film has proven to be a successful medium, when used to record photographically-reduced images of high-quality printouts of the computed diffraction pattern, as it was able to successfully reproduce complex light fields. It is believed that this will be the first time that this film has been implemented for optical trapping purposes. The main limitations concerning the performance of the holograms recorded on Kodalith were the phase nonuniformities caused by unevenness in the film thickness which resulted in a failure to separately resolve light traps separated by less than about 5 (Mu)m. Index matching of the film between sheets of flat glass helped to compensate for these limitations. Holographic optical trapping was successfully observed using a variety of different initial beam powers, holographic aperture settings and light field configurations. Trapping experiments on of two types of particles (PMMA and polystyrene) were successfully conducted, with as little as ~ 150 (Mu)W per trap being required for multiple polystyrene trapping. However, particles were weakly trapped and were easily dislodged at these powers, and a higher power per trap of around 1 mW is preferred. The use of a relatively low numerical aperture (NA) 50 mm SLR lens for focusing the holographic optical traps was successful, proving that optical trapping can be conducted without the use of high NA microscope-objective lenses commonly used in other set ups. Holographic trapping of colloidal particles was successfully conducted at RMIT University for the first time proving the validity of the coding scheme, the recording method and the trapping arrangement.

La présente thèse a pour objectif d'analyser la lumière structurée non-classique et ses caractéristiques. L'optique quantique et la lumière structurée sont deux sujets qui font l'objet d'examens nombreux. Ils sont néanmoins rarement examinés en combinaison. Les propriétés quantiques de la lumière structurée sont moins bien étudiées qu'ils devraient l'être. Par la lumière structurée nous entendons les champs lumineux qui montrent une structure transverse complexe de l'intensité, la phase ou la polarisation. Nous voulons lier les deux sujets de l'optique quantique et la lumière structurée dans la présente thèse. Dans ce but, nous générons expérimentalement des champs lumineux structurés non-classiques. En particulier, nous réalisons une expérience qui permet de générer des faisceaux vectoriels vectoriels - c'est-à-dire des faisceaux lumineux dont l'état de polarisation présente une structure transverse complexe - qui montrent une réduction du bruit quantique. En outre, nous étudions théoriquement les propriétés spatiales de faisceaux lumineux, ainsi que leur bruit. Plus spécifiquement, nous analysons l'incertitude quantique dans la largeur d'un faisceau lumineux. Pour prouver la faisabilité de la vérification expérimentales de nos résultats théoriques, nous réalisons des simulations pour la mesure de paramètres spatiales utilisant un détecteur mulitpixels. / This thesis aims at learning more about nonclassical structured light. Quantum optics and structured light are two topics that are subject to countless scientific examinations. However, they are very rarely combined and the quantum properties of structured light are not as thoroughly studied as they deserve. By structured light, we mean any light fields with complex transverse distributions of intensity, phase or polarization. We want to link the topics of quantum optics and structured light in this thesis. For this purpose, we experimentally generate particular nonclassical structured light fields. In particular, we construct an experimental setup that enables us, in principle, to produce arbitrary amplitude squeezed vector beams, i.e. light beams with a complex transverse structure of the state of polarization. Furthermore, we analyze spatial properties of light beams, and their quantum noise theoretically. We specifically perform theoretical examinations of the quantum noise in the width of a light beam. To show the feasibility of an experimental verification of our theoretical results, we conduct simulations for the measurement of spatial parameters of a beam's cross-section by a multipixel detector.

Free-space optics (FSO) is an unlicensed communication technology that uses the free space as a propagation medium to connect two communicating terminal wire- lessly [1]. It is an attractive solution to the last-mile connectivity problems in commu- nication networks, mainly when installing optical fibers is expensive or unavailable. A possible idea to increase the throughput of wireless optical links in free space is to use spatial multiplexing (SMM) [2]. Optical beam distortion due to propagation through a turbulent channel is one of the main factors limiting performance of such a system. Therefore, overcoming the effect of turbulence is a major problem for structured light optical communication in free space. Usually, this problem is approached by using adaptive optics systems and various methods of digital signal processing (DSP) on the receiver side [3–5]. Recently, an idea of optical channel pre-compensation to mit- igate inter-modal crosstalk was proposed [6] and experimentally validated [7]. Such a method, if implemented, will allow the use of entirely passive receivers or, in the case of full-duplex transmission, increase throughput. Here, the performance of a zero-forcing precoding technique to mitigate the effects of an optical turbulence in a Laguerre Gaussian mode based SMM FSO is investigated. Equally, details on a close to reality simulation of the atmospheric turbulence and beam propagation are provided.