Wireless cameras dominate the home surveillance market, providing an additional layer of security for homeowners. Cameras are not limited to private residences; retail stores, public bathrooms, and public beaches represent only some of the possible locations where wireless cameras may be monitoring people's movements. When cameras are deployed into an environment, one would typically expect the user to disclose the presence of the camera as well as its location, which should be outside of a private area. However, adversarial camera users may withhold information and prevent others from discovering the camera, forcing others to determine if they are being recorded on their own. To uncover hidden cameras, a wireless camera detection system must be developed that will recognize the camera's network traffic characteristics. We monitor the network traffic within the immediate area using a separately developed packet sniffer, a program that observes and collects information about network packets. We analyze and classify these packets based on how well their patterns and features match those expected of a wireless camera. We used a Support Vector Machine classifier and a secondary-level of classification to reduce false positives to design and implement a system that uncovers the presence of hidden wireless cameras within an area. / Master of Science / Wireless cameras may be found almost anywhere, whether they are used to monitor city traffic and report on travel conditions or to act as home surveillance when residents are away. Regardless of their purpose, wireless cameras may observe people wherever they are, as long as a power source and Wi-Fi connection are available. While most wireless camera users install such devices for peace of mind, there are some who take advantage of cameras to record others without their permission, sometimes in compromising positions or places. Because of this, systems are needed that may detect hidden wireless cameras. We develop a system that monitors network traffic packets, specifically based on their packet lengths and direction, and determines if the properties of the packets mimic those of a wireless camera stream. A double-layered classification technique is used to uncover hidden wireless cameras and filter out non-wireless camera devices.

Previsualization is a class of techniques for creating approximate previews of a movie sequence in order to visualize a scene prior to shooting it on the set. Often these techniques are used to convey the artistic direction of the story in terms of cinematic elements, such as camera movement, angle, lighting, dialogue, and character motion. Essentially, a movie director uses previsualization (previs) to convey movie visuals as he sees them in his "minds-eye". Traditional methods for previs include hand-drawn sketches, Storyboards, scaled models, and photographs, which are created by artists to convey how a scene or character might look or move. A recent trend has been to use 3D graphics applications such as video game engines to perform previs, which is called 3D previs. This type of previs is generally used prior to shooting a scene in order to choreograph camera or character movements. To visualize a scene while being recorded on-set, directors and cinematographers use a technique called On-set previs, which provides a real-time view with little to no processing. Other types of previs, such as Technical previs, emphasize accurately capturing scene properties but lack any interactive manipulation and are usually employed by visual effects crews and not for cinematographers or directors. This dissertation's focus is on creating a new method for interactive visualization that will automatically capture the on-set lighting and provide interactive manipulation of cinematic elements to facilitate the movie maker's artistic expression, validate cinematic choices, and provide guidance to production crews. Our method will overcome the drawbacks of the all previous previs methods by combining photorealistic rendering with accurately captured scene details, which is interactively displayed on a mobile capture and rendering platform. This dissertation describes a new hardware and software previs framework that enables interactive visualization of on-set post-production elements. A three-tiered framework, which is the main contribution of this dissertation is; 1) a novel programmable camera architecture that provides programmability to low-level features and a visual programming interface, 2) new algorithms that analyzes and decomposes the scene photometrically, and 3) a previs interface that leverages the previous to perform interactive rendering and manipulation of the photometric and computer generated elements. For this dissertation we implemented a programmable camera with a novel visual programming interface. We developed the photometric theory and implementation of our novel relighting technique called Symmetric lighting, which can be used to relight a scene with multiple illuminants with respect to color, intensity and location on our programmable camera. We analyzed the performance of Symmetric lighting on synthetic and real scenes to evaluate the benefits and limitations with respect to the reflectance composition of the scene and the number and color of lights within the scene. We found that, since our method is based on a Lambertian reflectance assumption, our method works well under this assumption but that scenes with high amounts of specular reflections can have higher errors in terms of relighting accuracy and additional steps are required to mitigate this limitation. Also, scenes which contain lights whose colors are a too similar can lead to degenerate cases in terms of relighting. Despite these limitations, an important contribution of our work is that Symmetric lighting can also be leveraged as a solution for performing multi-illuminant white balancing and light color estimation within a scene with multiple illuminants without limits on the color range or number of lights. We compared our method to other white balance methods and show that our method is superior when at least one of the light colors is known a priori.

Thesis (M.F.A.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (leaf 30).

Thesis (MScEng)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: We present all the components needed for a fully-fledged stereo vision system, ranging from object detection through camera calibration to depth perception. We propose an efficient, automatic and practical method to calibrate cameras for use in 3D machine vision metrology. We develop an automated stereo calibration system that only requires a series of views of a manufactured calibration object in unknown positions. The system is tested against real and synthetic data, and we investigate the robustness of the proposed method compared to standard calibration practice. All the aspects of 3D stereo reconstruction is dealt with and we present the necessary algorithms to perform epipolar rectification on images as well as solving the correspondence and triangulation problems. It was found that the system performs well even in the presence of noise, and calibration is easy and requires no specialist knowledge. / AFRIKAANSE OPSOMMING: Ons beskryf al die komponente van 'n omvattende stereo visie sisteem. Die kern van die sisteem is 'n effektiewe, ge-outomatiseerde en praktiese metode om kameras te kalibreer vir gebruik in 3D rekenaarvisie. Ons ontwikkel 'n outomatiese, stereo kamerakalibrasie sisteem wat slegs 'n reeks beelde van 'n kalibrasie voorwerp in onbekende posisies vereis. Die sisteem word getoets met reële en sintetiese data, en ons vergelyk die robuustheid van die metode met die standaard algoritmes. Al die aspekte van die 3D stereo rekonstruksie word behandel en ons beskryf die nodige algoritmes om epipolêre rektifikasie op beelde te doen sowel as metodes om die korrespondensie- en diepte probleme op te los. Ons wys dat die sisteem goeie resultate lewer in die aanwesigheid van ruis en dat kamerakalibrasie outomaties kan geskied sonder dat enige spesialis kennis benodig word.

[pt] O processo de calibração de câmeras é uma etapa importante na instalação dos sistemas de rastreamento óptico. Da qualidade da calibração deriva o funcionamento correto e preciso do sistema de rastreamento. Diversos métodos de calibração têm sido propostos na literatura em conjunto com o uso de artefatos sintéticos definidos como padrões de calibração. Esses padrões, de forma e tamanho conhecidos, permitem a aquisição de pontos de referência que são utilizados para a determinação dos parâmetros das câmeras. Para minimizar erros, esta aquisição deve ser feita em todo o espaço de rastreamento. A fácil identificação dos pontos de referência torna o processo de aquisição eficiente. A quantidade e a qualidade das relações geométricas das feições do padrão influenciam diretamente na precisão dos parâmetros de calibração obtidos. É nesse contexto que esta tese se encaixa, propondo um novo método para múltipla calibração de câmeras, que é eficiente e produz resultados tão ou mais precisos que os métodos atualmente disponíveis na literatura. Nosso método também propõe um novo tipo de padrão de calibração que torna a tarefa de captura e reconhecimento de pontos de calibração mais robusta e eficiente. Deste padrão também derivam relações que aumentam a precisão do rastreamento. Nesta tese o processo de calibração de múltiplas câmeras é revisitado e estruturado de forma a permitir uma comparação das principais propostas da literatura com o método proposto. Esta estruturação também dá suporte a uma implementação flexível que permite a reprodução numérica de diferentes propostas. Finalmente, este trabalho apresenta resultados numéricos que permitem tirar algumas conclusões. / [en] The calibration of multiple cameras is an important step in the installation of optical tracking systems. The accuracy of a tracking system is directly related to the quality of the calibration process. Several calibration methods have been proposed in the literature in conjunction with the use of artifacts, called calibration patterns. These patterns, with shape and size known, allow the capture of reference points to compute camera parameters. To yield good results these points must be uniformly distributed over the tracking area. The determination of the reference points in the image is an expensive process prone to errors. The use of a good calibration pattern can reduce these problems. This thesis proposes a new multiple camera calibration method that is efficient and yields better results than previously proposed methods available in the literature. Our method also proposes the use of a new simple calibration pattern based on perspective invariant properties and useful geometric properties. This pattern yields robust reference point identification and more precise tracking. This thesis also revisits the multiple calibration process and suggests a framework to compare the existing methods including the one proposed here. This framework is used to produce a flexible implementation that allows a numerical evaluation that demonstrates the benefits of the proposed method. Finally the thesis presents some conclusions and suggestions for further work.

[pt] A reconstrução de câmera é um dos problemas fundamentais da visão computacional. Sistemas de software desta área utilizam modelos matemáticos de câmera, ou câmeras virtuais, para, por exemplo, interpretar e reconstruir a estrutura tridimensional de uma cena real a partir de fotos e vídeos digitais ou para produzir imagens sintéticas com aparência realista. As técnicas de reconstruçã de câmera da visão computacional são aplicadas em conjunto com técnicas de realidade virtual para dar origem a novas aplicações chamadas de aplicações de realidade aumentada, que utilizam câmeras virtuais para combinar imagens reais e sintéticas em uma mesma foto digital. Dentre os diversos usos destes tipos de aplicação, este trabalho tem particular interesse naqueles que tratam de visitas aumentadas a edificações. Nestes casos, fotos de edificações — tipicamente de construções antigas ou ruínas — são reconstruídas a partir de modelos virtuais que são inseridos em meio a tais fotos digitais com a finalidade de habilitar a visão de como essas edificações eram em suas estruturas originais. Nesse contexto, este trabalho propõe um método semi-automático e eficiente para realizar tal reconstrução e registrar câmeras virtuais a partir de fotos reais e modelos computacionais de edificações, permitindo compará-los através de superposição direta e disponibilizando uma nova maneira de navegar de forma tridimensional por entre diversas fotos registradas. Tal método requer a participação do usuário, mas é projetado para ser simples e produtivo. / [en] Camera reconstruction is one of the major problems in computer vision. Software systems in that field uses mathematical camera models, or virtual cameras, for example, to interpret and reconstruct the tridimensional structure of a real scene from a set of digital pictures or videos or to produce synthetic images with realistic looking. Computer vision technics are applied together with virtual reality technics in order to originate new types of applications called augmented reality applications, which use virtual cameras to combine both real and synthetic images within a single digital image. Among the many uses of these types of applications, this work has particular interest in those concerning augmented visits to buildings. In these cases, pictures of buildings — typically old structures os ruins — are reconstructed from virtual models that are inserted into such pictures allowing one to have the vision of how those buildings were on they original appearance. Within this context, this work proposes a semi-automatic and efficient method to perform such reconstructions and to register virtual cameras from real pictures and models of buildings, allowing comparing them through direct superposing and making possible to navigate in a tridimensional fashion between the many registered pictures. Such method requires user interaction, but it is designed to be simple and productive.

No description available.

No description available.

Visual surveys provide for non-invasive sampling of organisms and habitats in the marine environment. They are particularly important in deep-sea habitats which are vulnerable to damage caused by alternative destructive sampling devices such as bottom trawls. However, traditional visual survey platforms tend to have limited area coverage which is insufficient for mapping the vast expanses of the deep-sea, particularly for relatively sparsely distributed organisms such as fish. This thesis presents the development of a visual survey method capable of surveying large areas of the seabed in deep waters (> 200 m) using a towed video camera system. The area of seabed sampled was similar to that sampled by a bottom trawl, making the system effective for surveying fish. Anglerfish densities were found to be comparable to those determined by trawl surveys in adjacent areas. For other deep-sea fish, the two survey methods (towed camera and bottom trawl) provided different results which were explained by the behavioural reactions of different fish taxa to the respective gears. Fish that exhibited detectable avoidance behaviour to the towed video camera system (e.g. Chimaeridae) resulted in significantly lower density estimates than trawl estimates. On the other hand, skates and rays showed no reaction to the towed video camera system, and density estimates of these were an order of magnitude higher than the trawl. The towed video camera survey was also deployed to gather data on the cold-water coral Lophelia pertusa on the Rockall Bank. These data were used together with Species Distribution Modelling (SDM) to predict the distribution of Lophelia pertusa habitat. The current closed areas on the Rockall Bank cover sizeable areas of potential Lophelia pertusa habitat, however, based on the predictions further areas could be considered to ensure the continued protection of this species.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy