User interactive high-resolution multi-view display system using a three-dimensional head-tracking camera

We have developed a teleconference system called MulDiRoH (Multi-Directional Representation of Humans). It features the use of a QDA screen, one of the newest multi-view display techniques. A principal benefit of multi-view displays is they can show views of a remote participant from the direction in which the participant’s face is pointing. This enables other participants to directly see the face of a remote participant who is actually looking away from them. However, all multi-view display systems share a common problem in that users who stand outside of the center area cannot observe geometrically correct images. To addressthis problem, we propose the use of the perspective transform method. We also evaluate the conveying of a person’s facial direction by a communication game for multiple users.

A light field print (LFP) displays three-dimensional (3D) information to the naked-eye observer under ambient white light illumination. Changing perspectives of a 3D image are seen by the observer from varying angles. However, LFPs appear pixelated due to limited resolution and misalignment between their lenses and colour pixels. A promising solution to create high-resolution LFPs is through the use of advanced nanofabrication techniques. Here, we use two-photon polymerization lithography as a one-step nanoscale 3D printer to directly fabricate LFPs out of transparent resin. This approach produces simultaneously high spatial resolution (29–45 µm) and high angular resolution (~1.6°) images with smooth motion parallax across 15 × 15 views. Notably, the smallest colour pixel consists of only a single nanopillar (~300 nm diameter). Our LFP signifies a step towards hyper-realistic 3D images that can be applied in print media and security tags for high-value goods.

In the last few years several multi-view display systems appeared increasing in size and the number of views that can be displayed. The increasing number of views allow for more realistic content with a high level of detail and complex lighting. For highest quality the images of synthetic scenes are usually ray traced. For large displays that are able to resolve a large amount of different views the number of viewing rays is enormous and it would take several month to render the content via ray tracing. One solution is to render only a few images and interpolate the remaining images with an image based rendering approach. This work introduces an algorithm that selects the best viewpoints for an image based rendering algorithm on the basis of given criteria. Special care is taken to cover occlusions and account for the dimension and angular resolution of multi-view displays.

We have developed an autostereoscopic multi view display with 36view using 15.1 ultra-high resolution LCD. The resolution of LCD used for experiment is QUXGA of 3200x2400. RGB sub pixels are aligned as vertical lines and size of each sub pixel is 0.032 mm by 0.096mm. Parallax barrier are slanted at the angle of tan -1 (1/6) = 9.46 degree and placed before LCD panel to generate viewing zones. Barrier patterns repeated approximately for every 6 pixels of LCD. So, the numbers of pixels decrease by six along the horizontal direction and the vertical direction. Nominal 3D resolution becomes (3200/6) x (2400/6) = 533 x 400. In slanted barrier configuration, the angular luminance profile for each zone overlaps each other. For the case of 2view 3D system, cross-talk between left eye and right eye zone deteriorates 3D image quality. However for multi view 3D, cross-talk between adjacent zones does not always bring about negative effects as image differences between adjacent zones are rather small. As viewers can see pixels from multiple viewing zones at one place, viewers feel 3D image of higher resolution than nominal 533x400 resolutions. Tested 3D images are made by computer graphics, in which camera position and depth of 3D objects are varied. Smooth motion parallax is observed for the limited depth range of 3D object. As depth of 3D object increases, 3D objects are observed not one image but as overlapped multiple images and image flipping becomes noticeable. We changed the barrier conditions so that horizontal angles between each zone are different and 3D image qualities were compared. For each barrier condition of different horizontal angle between viewing zones, we find an acceptable range of 3D object depth and camera displacement between each zone for computer generated images.

We presentPiCam(Pelican Imaging Camera-Array), an ultra-thin high performance monolithic camera array, that captures light fields and synthesizes high resolution images along with a range image (scene depth) through integrated parallax detection and superresolution. The camera is passive, supporting both stills and video, low light capable, and small enough to be included in the next generation of mobile devices including smartphones. Prior works [Rander et al. 1997; Yang et al. 2002; Zhang and Chen 2004; Tanida et al. 2001; Tanida et al. 2003; Duparré et al. 2004] in camera arrays have explored multiple facets of light field capture - from viewpoint synthesis, synthetic refocus, computing range images, high speed video, and micro-optical aspects of system miniaturization. However, none of these have addressed the modifications needed to achieve the strict form factor and image quality required to make array cameras practical for mobile devices. In our approach, we customize many aspects of the camera array including lenses, pixels, sensors, and software algorithms to achieve imaging performance and form factor comparable to existing mobile phone cameras.Our contributions to the post-processing of images from camera arrays include a cost function for parallax detection that integrates across multiple color channels, and a regularized image restoration (superresolution) process that takes into account all the system degradations and adapts to a range of practical imaging conditions. The registration uncertainty from the parallax detection process is integrated into a Maximum-a-Posteriori formulation that synthesizes an estimate of the high resolution image and scene depth. We conclude with some examples of our array capabilities such as postcapture (still) refocus, video refocus, view synthesis to demonstrate motion parallax, 3D range images, and briefly address future work.

The Internet of Things technology has brought a lot of convenience to regional situation monitoring. Facing complex and interrelated monitoring methods, IoT systems need to access a variety of sensor devices. It is necessary to comprehensively display a large number of multi-source heterogeneous sensing data. The existing work can access multi-source heterogeneous sensor devices and display the sensing data of different devices on different visual interfaces. However, the information displayed by the system lacks relevance, and it is difficult to clarify the relationship between different sensor data, and it is impossible to display comprehensive information after merging multi-sensor data. Moreover, there is few work that meet the needs of query and playback of historical data. This paper designs and implements a real-time and historical multi-view IoT trend system to deal with the mentioned problems. Using the target information graph, it displays the relationship between different sensor data, and using the method combined real time and history, it proposes a buffered batch data loading algorithm to form a dual-display mode system. An IoT trend simulation platform based on B/S-MVC-MVVM architecture was built. Based on this platform, multi-source heterogeneous sensor data is accessed. The experimental results show that the system can display the relevance of the information and realize the historical data playback effect.

There is often confusion among the general public between holograms and the type of contemporary 3D images seen in movie theaters, in which viewers from each side of the theater see the same image on the screen. As astonishing as these 3D effects are, the technologies used are typically based on either polarization stereoscopy (the technique currently used in cinemas and 3D television), digital image fusion, or 2D semitransparent screens. These techniques have little to do with holography, which is based on the reproduction of not only the amplitude but also the phase of light by diffraction. These 3D images can have depth but are typically filmed from a single perspective. On the other hand, for a viewer moving around a hologram, the appearance of the object changes continuously and smoothly as the viewer’s perspective changes, as if the object is real. A standard 3D movie camera (which actually uses two cameras) captures light scattered from an object at two different angles, one for each eye, from a single perspective. However, in the real world, light reflects from objects at an infinite number of angles. For a 3D television viewing experience to be maximally realistic, it must be autostereoscopic (requiring no glasses), present continuous parallax (rather than just stereopsis), and realistically represent other perceptual depth cues, such as proper visual accommodation (focusing) and vergence. The display technology most likely able to offer these features is holographic television. Some recent 3D display technologies, though not necessarily holographic, have been commercialized due to the increasing demand from the public for autostereoscopic 3D TVs, 3D games, and mobile devices equipped with 3D displays. This chapter systematically reviews various 3D display technologies. Byoungho Lee et.al. and Jason Geng have recently published excellent review articles concerning many state-of-the-art 3D display technologies, which will be summarized in this chapter.

In this paper, a three-dimensional (3D) image security system combines the use of the smart pixel mapping (SPM)algorithm and the Fibonacci transformation technique is proposed. In order to reconstruct orthoscopic 3D images withimproved image quality, a smart pixel mapping process is adopted. Based on the SPM-based computational integralimaging (CII) system, the depth-converted elemental image array (EIA) is obtained for increasing the quality of thereconstructed image. In the encryption process, the depth-converted EIA is scrambled by the Fibonacci transformation(FT) algorithm. Meanwhile, the computational integral imaging reconstruction (CIIR) technique is used to reconstructthe 3D image in the image reconstruction process. Compared with conventional CII-based 3D image encryptionmethods, the proposed method enable us to reconstruct high-resolution orthoscopic 3D images at long distance. Todemonstrate the effectiveness of the proposed method, some numerical experiments are made to test the validity andthe capability of the proposed 3D image security system.

In the 3-D display field, super multi-view (SMV) technology has drawn keen attention owing to its advanced 3-D features: smooth motion parallax, wide depth of focus, and a possibility of visual discomfort alleviation. Nevertheless, its applications are limited because of narrow viewing lobes (VLs), unavoidable to prevent an excessive decrease of the lateral resolution. To expand VLs, many head-tracked multi-view display technologies have been developed for decades, but restrictive viewing distance (VD) still remains as one of the most critical drawbacks of SMV technology. This paper proposes a novel method that can adjust the optimal VD (OVD) in flat-panel-based SMV displays without mechanical changes or loss of multi-view properties. To this end, it exploits partially aperiodically located sets of subpixels for defining 3-D pixels and dynamically changing view indices for the 3-D pixels. This enables that the front and rear bounds of initial VDs are adjustable, and VLs are dynamically expandable when a target OVD is renewed in real time using head-tracking. In the experiments, the quantitative VL expansion and qualitative quality of perceptual images are compared, and the feasibility of supporting adaptive VD in real time is further investigated. In addition, our prototype head-tracked SMV system is also introduced as an advanced application towards omnidirectionally free VL.

A method for displaying clear floating images in a crystal ball is proposed. Its symmetric optics can provide clear and natural 360‐degree images with smooth motion parallax in horizontal and vertical directions using the directional selectivity of a spatially imaged iris method and natural 3D images of a Multiview DFD display.

Assessment of mandibular growth and response to orthopedic treatment with 3-dimensional magnetic resonance images

The Spreading Projection Algorithm for Rapid K-space sampLING, or SPARKLING, is an optimization-driven method that has been recently introduced for accelerated 2D MRI using compressed sensing. It has then been extended to address 3D imaging using either stacks of 2D sampling patterns or a local 3D strategy that optimizes a single sampling trajectory at a time. 2D SPARKLING actually performs variable density sampling (VDS) along a prescribed target density while maximizing sampling efficiency and meeting the gradient-based hardware constraints. However, 3D SPARKLING has remained limited in terms of acceleration factors along the third dimension if one wants to preserve a peaky point spread function (PSF) and thus good image quality. In this paper, in order to achieve higher acceleration factors in 3D imaging while preserving image quality, we propose a new efficient algorithm that performs optimization on full 3D SPARKLING. The proposed implementation based on fast multipole methods (FMM) allows us to design sampling patterns with up to 107 k-space samples, thus opening the door to 3D VDS. We compare multi-CPU and GPU implementations and demonstrate that the latter is optimal for 3D imaging in the high-resolution acquisition regime ( 600μ m isotropic). Finally, we show that this novel optimization for full 3D SPARKLING outperforms stacking strategies or 3D twisted projection imaging through retrospective and prospective studies on NIST phantom and in vivo brain scans at 3 Tesla taking the particular case of T2 *-w imaging. Overall the proposed method allows for 2.5-3.75x shorter scan times compared to GRAPPA-4 parallel imaging acquisition at 3 Tesla without compromising image quality.

Multi-slice 2D turbo spin echo (TSE) sequences are widely used for T2-weighted MR imaging of the liver. On the other hand, there is a demand for 3D imaging to enable the observation of thinner slices, though 3D TSE has often been associated with a high SAR (specific absorption rate) which is caused by repeated 180-degree refocusing pulses. The high SAR has been a limiting factor for 3D TSE, especially with 3.0 Tesla scanners. We carried out free-breath 3D SPACE T2-weighted MR imaging of the liver to yield TSE contrast. This is a variant of 3D TSE that employs specially-designed refocusing pulses to reduce the SAR. The PACE (prospective acquisition correction) technique was used to eliminate motion artifacts that appear conspicuously at 3 Tesla as compared with 1.5 Tesla. The 3D SPACE parameters were as follows; FOV=384mm and base matrix size=320, effective slice thickness=1.2mm. Five volunteers were examined with this sequence on a 3.0-Tesla whole-body scanner. The acquired isotropic 3D image data set was processed with both multi-planar reconstruction (MPR) and volume rendering technique (VRT) to yield images with high quality and very distinct continuity. Such processing was possible due to the isotropic 1.2-mm resolution made feasible by the 3D SPACE sequence. 3D T2-weighted imaging of the liver was performed successfully and safely by combining 3D SPACE and PACE, and the high-resolution isotropic image data assured the continuity of blood vessels and the cystic duct of the liver. I.

In response to the letter by Aps1 concerning our papers published in DMFR2 and the September 2012 issue of the European Journal of Paediatric Dentistry (EJPD),3 we would like to provide clarification and evidence of the careful approach taken to the orthodontic and radiological procedures employed in these studies. Importantly, we would like to clarify that the authors do not use ionizing radiation as a daily orthodontic diagnostic tool. Careful dosage and ionizing radiation should be used only in specific clinical conditions such as impacted canines, supernumerary teeth and temporomandibular joint arthritis, and in planning orthognathic surgery.4 As was reported clearly in the article and could be seen easily in the figures, all patients in the study sample presented with severely displaced maxillary canines. Canine impaction is one of the clinical conditions in orthodontics for which evidence-based research for the clinical application of three-dimensional (3D) imaging exists. Thus, the primary indication for the low-dose CT was to evaluate the position of displaced intraosseus canines in the maxilla. These data cannot be detected using dental casts. While it is true that the position of the crown determines the surgical approach and direction of traction, the direction of eruption and location of the root apex play important roles in the orthodontic mechanics, avoiding damage to adjacent teeth and improving the effectiveness of canine traction.5 Hofmann et al6 developed a system on 3D imaging that allows for accurate evaluation of the position of the displaced canines relative to three spatial planes. The Department of Orthodontics at the University of Rome “Tor Vergata” is specialized in the treatment of impacted canines often associated with other dental anomalies such as supernumerary teeth and missing or peg-shaped lateral incisors.7,8 Consequently, we applied the protocol reported in several papers9–12 demonstrating that rapid maxillary expansion (RME) is an orthopaedic procedure that improves the initial intraosseus position of the canines and increases the rate of eruption of palatally displaced maxillary canines compared with an untreated control group. The present study sample is a very unique sample in the literature, and it allowed for scientific investigation of the skeletal, dental and periodontal effects of RME, one of the procedures most commonly applied and most debated in orthodontics. All of these effects (which cannot be derived using dental casts only) were analysed using the same sample in different publications by our research group.2,13–16 The imaging protocol in the present study was carefully planned with our radiologist to minimize patient dosage in low-resolution and small field of view (FOV) image acquisitions. The trained radiology technician reduced the voltage to the lowest possible level (80 kV) and restricted the area investigated strictly to the maxilla, adapting the FOV from a minimum of 6 cm to a maximum of 13 cm. Despite this, the accuracy of the measurements performed was not compromized. With this careful imaging protocol, the radiation dosage of three low-dose CT scans, considering their stochastic effect, is much smaller and not comparable to one multislice skull CT. The two images published in the EJPD demonstrate, contrary to what is claimed by Professor Aps, the high level of standardization involved where imaging acquisition was carried out by a single radiographer at the same scanner console, and the careful positioning of the patients' heads. Head position was standardized using perpendicular light beams, and the axial CT images were reconstructed always as parallel to the palatal plane and passing through the trifurcation of the right upper first molar, with the same method reported in numerous previous articles.17–28 For this reason, it was not necessary to add a figure; in addition, with the device in situ, it was possible to draw clearly the circle area because the expander was located in a more occlusal position at crown level, while the axial images were at the root level of anchored tooth. We thank Professor Aps for sharing the link to Image Gently, which is an initiative we certainly applaud. We absolutely agree that imaging as gently as possible, keeping the patient benefits and risks in mind, is our most sincere goal. In summary, as paediatric dentists, we are guarding over the health of our young patients, and as orthodontists, it is our duty to plan a treatment as conservative as possible, especially in clinical cases that need a combined surgical–orthodontic approach. Thus, all subjects of the study sample benefited from this research protocol and achieved successful treatment outcomes thanks to adequate treatment planning based on careful use of the right diagnostic tools.

To resolve separated viewing zones, a one-dimensional dual-view integral imaging three-dimensional (3D) display based on a polarizer parallax barrier was proposed. The imaging model of the one-dimensional dual-view integral imaging 3D display based on the polarizer parallax barrier was established. The principle of the one-dimensional dual-view integral imaging 3D display was illustrated in detail. The calculation formulas of the width of the viewing zone and the viewing angle were deduced by using geometrical optics. A test equipment of the one-dimensional dual-view integral imaging 3D display was developed. By using left and right polarizer parallax barriers, two different 3D images were viewed from 18° to the left and the right in the same viewing zone.