Three-dimensional photography as a new technique to make didactic presentations more attractive

In the 21st century, the form of presenting information plays an incredibly important role in arousing interest in research problems. Stereoscopy is among the imaging techniques that have evoked much interest in the recent years. Its numerous applications that can be observed in various fields (such as medicine, space science, law, marketing, or entertainment industry) suggest that we should also use this technology for didactic purposes. The aim of the article is to discuss the process of creating threedimensional photography and the opportunities offered by stereoscopy, which makes it possible to obtain images with depth effect and impression of solidity. The authors describe different ways to obtain threedimensional images and the devices applied in the process, as well as techniques of presenting threedimensional material to a wider audience. The methods of free-viewing (the oldest method of viewing stereoscopic images), anaglyph (a simple method applied in printing and displaying static images and movies on screen), lenticular raster (employing a series of narrow vertical cylindrical lenses), and stereoscopy (in which mirrors, lenses, prisms, or filters are used) are discussed. Also, the application of computer technology is reviewed and the ways in which stereoscopy can benefit from this medium owing to the use of LCD shutter glasses. Contemporary technology offers considerable opportunities, at the same time posing ever-increasing demands, which are mentioned in the paper, too. Teaching is most effective when information is received through multiple channels, combining verbal and visual messages. Owing to 3D images, the recipients grasp more information details, remember them longer, and are more interested in the message content. Creating didactic presentations with the use of three-dimensional photographs or films is presented as a way of arousing interest, allowing direct participation in the cognitive process, and facilitating the reception of the transmitted content

Acceleration Techniques for Photo Realistic Computer Generated Integral Images

The research work presented in this thesis has approached the task of accelerating the generation of photo-realistic integral images produced by integral ray tracing. Ray tracing algorithm is a computationally exhaustive algorithm, which spawns one ray or more through each pixel of the pixels forming the image, into the space containing the scene. Ray tracing integral images consumes more processing time than normal images. The unique characteristics of the 3D integral camera model has been analysed and it has been shown that different coherency aspects than normal ray tracing can be investigated in order to accelerate the generation of photo-realistic integral images. The image-space coherence has been analysed describing the relation between rays and projected shadows in the scene rendered. Shadow cache algorithm has been adapted in order to minimise shadow intersection tests in integral ray tracing. Shadow intersection tests make the majority of the intersection tests in ray tracing. Novel pixel-tracing styles are developed uniquely for integral ray tracing to improve the image-space coherence and the performance of the shadow cache algorithm. Acceleration of the photo-realistic integral images generation using the image-space coherence information between shadows and rays in integral ray tracing has been achieved with up to 41 % of time saving. Also, it has been proven that applying the new styles of pixel-tracing does not affect of the scalability of integral ray tracing running over parallel computers. The novel integral reprojection algorithm has been developed uniquely through geometrical analysis of the generation of integral image in order to use the tempo-spatial coherence information within the integral frames. A new derivation of integral projection matrix for projecting points through an axial model of a lenticular lens has been established. Rapid generation of 3D photo-realistic integral frames has been achieved with a speed four times faster than the normal generation

HOLOGRAPHICS: Combining Holograms with Interactive Computer Graphics

Among all imaging techniques that have been invented throughout the last decades, computer graphics is one of the most successful tools today. Many areas in science, entertainment, education, and engineering would be unimaginable without the aid of 2D or 3D computer graphics. The reason for this success story might be its interactivity, which is an important property that is still not provided efficiently by competing technologies – such as holography. While optical holography and digital holography are limited to presenting a non-interactive content, electroholography or computer generated holograms (CGH) facilitate the computer-based generation and display of holograms at interactive rates [2,3,29,30]. Holographic fringes can be computed by either rendering multiple perspective images, then combining them into a stereogram [4], or simulating the optical interference and calculating the interference pattern [5]. Once computed, such a system dynamically visualizes the fringes with a holographic display. Since creating an electrohologram requires processing, transmitting, and storing a massive amount of data, today’s computer technology still sets the limits for electroholography. To overcome some of these performance issues, advanced reduction and compression methods have been developed that create truly interactive electroholograms. Unfortunately, most of these holograms are relatively small, low resolution, and cover only a small color spectrum. However, recent advances in consumer graphics hardware may reveal potential acceleration possibilities that can overcome these limitations [6]. In parallel to the development of computer graphics and despite their non-interactivity, optical and digital holography have created new fields, including interferometry, copy protection, data storage, holographic optical elements, and display holograms. Especially display holography has conquered several application domains. Museum exhibits often use optical holograms because they can present 3D objects with almost no loss in visual quality. In contrast to most stereoscopic or autostereoscopic graphics displays, holographic images can provide all depth cues—perspective, binocular disparity, motion parallax, convergence, and accommodation—and theoretically can be viewed simultaneously from an unlimited number of positions. Displaying artifacts virtually removes the need to build physical replicas of the original objects. In addition, optical holograms can be used to make engineering, medical, dental, archaeological, and other recordings—for teaching, training, experimentation and documentation. Archaeologists, for example, use optical holograms to archive and investigate ancient artifacts [7,8]. Scientists can use hologram copies to perform their research without having access to the original artifacts or settling for inaccurate replicas. Optical holograms can store a massive amount of information on a thin holographic emulsion. This technology can record and reconstruct a 3D scene with almost no loss in quality. Natural color holographic silver halide emulsion with grain sizes of 8nm is today’s state-of-the-art [14]. Today, computer graphics and raster displays offer a megapixel resolution and the interactive rendering of megabytes of data. Optical holograms, however, provide a terapixel resolution and are able to present an information content in the range of terabytes in real-time. Both are dimensions that will not be reached by computer graphics and conventional displays within the next years – even if Moore’s law proves to hold in future. Obviously, one has to make a decision between interactivity and quality when choosing a display technology for a particular application. While some applications require high visual realism and real-time presentation (that cannot be provided by computer graphics), others depend on user interaction (which is not possible with optical and digital holograms). Consequently, holography and computer graphics are being used as tools to solve individual research, engineering, and presentation problems within several domains. Up until today, however, these tools have been applied separately. The intention of the project which is summarized in this chapter is to combine both technologies to create a powerful tool for science, industry and education. This has been referred to as HoloGraphics. Several possibilities have been investigated that allow merging computer generated graphics and holograms [1]. The goal is to combine the advantages of conventional holograms (i.e. extremely high visual quality and realism, support for all depth queues and for multiple observers at no computational cost, space efficiency, etc.) with the advantages of today’s computer graphics capabilities (i.e. interactivity, real-time rendering, simulation and animation, stereoscopic and autostereoscopic presentation, etc.). The results of these investigations are presented in this chapter

Capturing Culture: The Practical Application of Holographic Recording for Artefacts Selected from the Heritage and Museums of the Arabian Peninsula

Recording cultural heritage is one of the most important issues for consideration in the twenty- first century. Safeguarding, protecting and preserving heritage, through effective mechanism, is of crucial importance. Holographic technology has the potential to offer an appropriate solution to solve issues in documenting, cataloguing and replaying the original optical information of the artefact in three-dimensional imaging. This thesis investigates the relationship between art and technology through holograms recorded as part of a practice-based research programme. It questions whether the holographic medium can be used to capture and disseminate information for use in audience interaction, and therefore raise public awareness, by solving the problem of displaying the original artefacts outside the museum context. Using holographic records of such valuable items has the potential to save them from being lost or destroyed, and opens up the prospect of a new form of virtual museum. This research examines the possibility of recording valuable and priceless artefacts using a mobile holographic recording system designed for museums. To this end, historical, traditional and cultural artefacts on display in Saudi heritage museums have been selected. This project involves the recording of ancient Arabian Peninsula cultural heritage, and in particular jewellery artefacts that we perceive as three-dimensional images created, using holographic wavefront information. The research adopts both qualitative and quantitative research methods and critical review of relevant literature on the holographic medium to determine how it might provide an innovative method of engaging museums in Saudi Arabia. The findings of this research offer an original contribution to knowledge and understanding for scholars concerned with conservation of Saudi Arabia’s cultural heritage

Depth measurement in integral images.

The development of a satisfactory the three-dimensional image system is a constant pursuit of the scientific community and entertainment industry. Among the many different methods of producing three-dimensional images, integral imaging is a technique that is capable of creating and encoding a true volume spatial optical model of the object scene in the form of a planar intensity distribution by using unique optical components. The generation of depth maps from three-dimensional integral images is of major importance for modern electronic display systems to enable content-based interactive manipulation and content-based image coding. The aim of this work is to address the particular issue of analyzing integral images in order to extract depth information from the planar recorded integral image. To develop a way of extracting depth information from the integral image, the unique characteristics of the three-dimensional integral image data have been analyzed and the high correlation existing between the pixels at one microlens pitch distance interval has been discovered. A new method of extracting depth information from viewpoint image extraction is developed. The viewpoint image is formed by sampling pixels at the same local position under different micro-lenses. Each viewpoint image is a two-dimensional parallel projection of the three-dimensional scene. Through geometrically analyzing the integral recording process, a depth equation is derived which describes the mathematic relationship between object depth and the corresponding viewpoint images displacement. With the depth equation, depth estimation is then converted to the task of disparity analysis. A correlation-based block matching approach is chosen to find the disparity among viewpoint images. To improve the performance of the depth estimation from the extracted viewpoint images, a modified multi-baseline algorithm is developed, followed by a neighborhood constraint and relaxation technique to improve the disparity analysis. To deal with the homogenous region and object border where the correct depth estimation is almost impossible from disparity analysis, two techniques, viz. Feature Block Pre-selection and “Consistency Post-screening, are further used. The final depth maps generated from the available integral image data have achieved very good visual effects

End-to-end 3D video communication over heterogeneous networks

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Three-dimensional technology, more commonly referred to as 3D technology, has revolutionised many fields including entertainment, medicine, and communications to name a few. In addition to 3D films, games, and sports channels, 3D perception has made tele-medicine a reality. By the year 2015, 30% of the all HD panels at home will be 3D enabled, predicted by consumer electronics manufacturers. Stereoscopic cameras, a comparatively mature technology compared to other 3D systems, are now being used by ordinary citizens to produce 3D content and share at a click of a button just like they do with the 2D counterparts via sites like YouTube. But technical challenges still exist, including with autostereoscopic multiview displays. 3D content requires many complex considerations--including how to represent it, and deciphering what is the best compression format--when considering transmission or storage, because of its increased amount of data. Any decision must be taken in the light of the available bandwidth or storage capacity, quality and user expectations. Free viewpoint navigation also remains partly unsolved. The most pressing issue getting in the way of widespread uptake of consumer 3D systems is the ability to deliver 3D content to heterogeneous consumer displays over the heterogeneous networks. Optimising 3D video communication solutions must consider the entire pipeline, starting with optimisation at the video source to the end display and transmission optimisation. Multi-view offers the most compelling solution for 3D videos with motion parallax and freedom from wearing headgear for 3D video perception. Optimising multi-view video for delivery and display could increase the demand for true 3D in the consumer market. This thesis focuses on an end-to-end quality optimisation in 3D video communication/transmission, offering solutions for optimisation at the compression, transmission, and decoder levels.Brunel University - Isambard Research Scholarshi

Perceived Depth Control in Stereoscopic Cinematography

Despite the recent explosion of interest in the stereoscopic 3D (S3D) technology, the ultimate prevailing of the S3D medium is still significantly hindered by adverse effects regarding the S3D viewing discomfort. This thesis attempts to improve the S3D viewing experience by investigating perceived depth control methods in stereoscopic cinematography on desktop 3D displays. The main contributions of this work are: (1) A new method was developed to carry out human factors studies on identifying the practical limits of the 3D Comfort Zone on a given 3D display. Our results suggest that it is necessary for cinematographers to identify the specific limits of 3D Comfort Zone on the target 3D display as different 3D systems have different ranges for the 3D Comfort Zone. (2) A new dynamic depth mapping approach was proposed to improve the depth perception in stereoscopic cinematography. The results of a human-based experiment confirmed its advantages in controlling the perceived depth in viewing 3D motion pictures over the existing depth mapping methods. (3) The practicability of employing the Depth of Field (DoF) blur technique in S3D was also investigated. Our results indicate that applying the DoF blur simulation on stereoscopic content may not improve the S3D viewing experience without the real time information about what the viewer is looking at. Finally, a basic guideline for stereoscopic cinematography was introduced to summarise the new findings of this thesis alongside several well-known key factors in 3D cinematography. It is our assumption that this guideline will be of particular interest not only to 3D filmmaking but also to 3D gaming, sports broadcasting, and TV production

Crosstalk in stereoscopic displays: A review

Crosstalk, also known as ghosting or leakage, is a primary factor in determining the image quality of stereoscopic three dimensional (3D) displays. In a stereoscopic display, a separate perspective view is presented to each of the observer’s two eyes in order to experience a 3D image with depth sensation. When crosstalk is present in a stereoscopic display, each eye will see a combination of the image intended for that eye, and some of the image intended for the other eye—making the image look doubled or ghosted. High levels of crosstalk can make stereoscopic images hard to fuse and lack fidelity, so it is important to achieve low levels of crosstalk in the development of high-quality stereoscopic displays. Descriptive and mathematical definitions of these terms are formalized and summarized. The mechanisms by which crosstalk occurs in different stereoscopic display technologies are also reviewed, including micropol 3D liquid crystal displays (LCDs), autostereoscopic (lenticular and parallax barrier), polarized projection, anaglyph, and time-sequential 3D on LCDs, plasma display panels and cathode ray tubes. Crosstalk reduction and crosstalk cancellation are also discussed along with methods of measuring and simulating crosstalk