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With the development of the information industry, the wearable three‐dimensional (3D) near‐eye display that can provide complete visual information has attracted increasing attention. Compared with other existing 3D display technologies, the holographic display is a promising true 3D display technology that can fully record and reproduce the original 3D scenes. The ability to present a continuous parallax and depth perception gives holography technology an unprecedented promise in the next‐generation 3D near‐eye display. However, currently available holographic near‐eye display systems can only provide a limited viewing area (including the field of view and eyebox), greatly restricting its practical application. Focusing on the development requirements of large viewing‐area 3D holographic near‐eye display, the reasons are introduced first why the viewing area of current holographic displays is limited and then the existing solutions from different aspects, including multiplexing‐based methods, steering viewing window methods, aperiodic wavefront modulation methods, and some emerging holographic display technologies are summarized. These various solutions are analyzed respectively, and their representative works are investigated. In addition, the different applications of holography in the near‐eye display system are also discussed. Finally, the advantages and disadvantages of these techniques are compared and perspectives are given. [ABSTRACT FROM AUTHOR]

Compared with traditional two‐dimensional displays, three‐dimensional displays can bring users a more realistic visual experience. In recent years, with the development of naked eye 3D technology, users can completely get rid of the shackles of glasses and experience stereoscopic visual effects more freely. The 3D display technology based on the cylindrical lens is a vital technology branch in the field of stereoscopic display. The lens light splitting and eye tracking technology are used to ensure that the image taken into the human eye at any viewing angle has correct parallax, thus giving people a three‐dimensional feeling. BOE has accumulated numerous technologies in the display field, especially in the fields of high‐resolution display and new display. This paper focuses on the space reality display system independently developed by BOE. [ABSTRACT FROM AUTHOR]

Electronic holographic displays can reconstruct the optical wavefront of object light, exhibiting the most realistic three-dimensional (3D) images, in contrast to conventional stereoscopic displays. In this paper, we propose a novel, near-eye holographic 3D display (NEHD) applicable to AR/MR/holographic devices and experimentally demonstrate the proposed module's performance with 360° full-viewed holographic 3D movie at 30 fps. To realize high-quality of reconstructed holographic 3D (H3D) images, we also propose an advanced amplitude-modulating (AM) encoding scheme suited for the proposed amplitude-modulating NEHD. We experimentally verify that the new hologram-encoding approach can improve the image quality of H3D reconstructions through quantitative statistical analyses, by using evaluation methods for H3D images that are suggested in the paper. Two holograms at different viewing directions of the same 3D scene are designed to be displayed onto the proposed NEHD prototype for two eyes of an observer, respectively. The presented techniques for the proposed NEHD enable the observer to experience the depth cue, a realistic accommodation effect, and high-quality H3D movies at each eye. [ABSTRACT FROM AUTHOR]

Electronic holography is an ideal 3-D display technique to ameliorate the vergence-accommodation conflict, which is a possible cause of visual fatigue and discomfort from viewing conventional stereoscopic 3-D displays. Previous studies have measured accommodative and vergence responses to holographic images and to real objects, and the results showed that these responses are in good agreement. To demonstrate the effectiveness of electronic holography as a possible solution to the vergence-accommodation conflict caused by viewing conventional stereoscopic 3-D displays, we measured both accommodative and vergence responses to reconstructed images of holograms and super multiview holographic stereograms. We also measured responses to real objects located at various distances and conventional two-view stereo images for comparison. The results indicate that the accommodative responses to the electro-holographic display and super multiview holographic stereogram change with the vergence response in a similar manner, as is the case with real objects as compared to conventional two-view stereo display. This suggests that the electronic holographic display and super multiview holographic stereograms are promising candidates for resolving the vergence-accommodation conflict. [ABSTRACT FROM AUTHOR]

In this paper, we present an optically transparent multi‐planar 3D display device based on multi‐passive matrixed coded pixelated polymer‐dispersed liquid crystals (PDLC). The PDLC film used in this experiment has high transparency transmission (97.1%) and fast switching time characteristics within 20ms. We provide a method to display different depth‐of‐field images by layering them on a multi‐layer screen, by which it is possible to render near and far views in different planes, thus bringing 3‐dimensional visual information to the observer, ultimately A proof‐of‐concept prototype of a dual‐plane 3D display has been realized. [ABSTRACT FROM AUTHOR]

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Three-dimensional (3D) visualization is applied throughout many specialities, prompting an important breakthrough in accessibility and modeling of data. Experimental rendering and computerized reconstruction of objects has influenced many scientific achievements, facilitating one of the greatest advancements in medical education since the first illustrated anatomy book changed specialist training forever. Modern medicine relies on detailed, high quality virtual models for educational, experimental and clinical purposes. Almost all current virtual visualization methods rely on object slicing producing serial sections, which can then be digitalized or analyzed manually. The tendency to computerize serial sections roots from convenience, accessibility, decent visualization quality and automation capabilities. Drawbacks of serial section imaging is tissue damage occurring within each consequent sectioning. To utilize the important aspects of real-life object reconstruction, and maintain integrity of biological structures, we suggest a novel method of low-temperature layering of objects for digitization and computerized virtual reconstruction. Here we show the process of consequent imaging of each novel layer of a biological object, which provides a computer with high quality data for virtual reconstruction and creation of a multidimensional real-life model. Our method prevents tissue deformation and biodegradation due to specific methods used in preparation of the biological object. The resulting images can be applied in surgical training, medical education and numerous scientific fields for realistic reconstruction of biological objects. [ABSTRACT FROM AUTHOR]

Holographic display technology can reconstruct the same images of the original objects exactly, which has played a more and more important role and become the goal of the three‐dimensional display. As liquid crystal devices can modulate the polarization state of light, they have been widely used in the holographic display to modulate the phase and amplitude of information. Among them, liquid crystal spatial light modulator and liquid crystal lens are two important devices in the holographic diffraction. In this paper, several liquid crystal devices have been introduced and the holographic display technologies based on these liquid crystal devices have been discussed. The merits and demerits of these technologies based on the liquid crystal devices have been analyzed, and the outlook of the holographic display is given in the end. [ABSTRACT FROM AUTHOR]

Three-dimensional light-field displays (3D-LFDs) can provide viewers with glass-free 3D images. The display effect of reconstructed 3D images is closely related to the number of 3D object points that the 3D display system can construct, which can be regarded as the information quantity of the 3D-LFDs. However, the information quantity presented by a 3D-LFD is limited by fixed hardware parameters such as display panels and optical components. It is difficult to present an ideal 3D visual experience with the increase in display depth. In this paper, an analytical model based on voxel construction for 3D-LFDs is proposed, which can estimate the information quantity that a 3D-LFD can reproduce. The variation regularity of information quantity with display depth is analyzed and the influence of hardware parameters on display effect is discussed. With the proposed strategies, the display effect can be improved in a targeted manner without blurring and aliasing by adjusting the hardware parameters in display systems and matching the information quantity at different display depths. • A general analytical model of 3D light field displays was constructed. • The influence of optical components parameters on display effect were analyzed. • Derive the variation regularity between display depth and information quantity. • Experiments were conducted to verify the validity of the analysis model. [ABSTRACT FROM AUTHOR]

• The Nyquist frequency limitation is overcome by holographic diffuser. • The effective visual-spatial frequency is increased by holographic diffuser. • Holographic diffuser can greatly improve the display quality of InIm display system. A holographic diffuser can effectively improve the viewable quality of a large-scale integral imaging system. In this paper, a beam diffusion model of the holographic diffuser is designed and constructed to analyze the performance of holographic diffuser based integral imaging system quantitatively, and the mechanism improving the display effect is analyzed by characterization of visual-spatial frequency and effective visual 3D information. The theoretical analysis indicates that the holographic diffuser can effectively enlarge the visible range of reconstructed rays, overcome the Nyquist frequency limitation, and increase the effective visual-spatial frequency and the effective visual 3D information of the display system. The experimental results verify the theoretical prediction proving the holographic diffuser can effectively improve the display quality of the integral imaging display system. [ABSTRACT FROM AUTHOR]

Abstract We propose a 360-degree viewable tabletop three-dimensional (3D) display system based on integral imaging by using a perspective-oriented layer (POL). The proposed system is composed of a two-dimensional (2D) display device, a POL, a lens array with large pitch and a light shaping diffuser screen. The 2D display device with high refresh rate is utilized to present the adaptive element image array (AEIA) sequentially. The AEIA is generated based on partially-overlapping algorithm to ensure that the 3D image corresponding to adjacent viewing zone is reconstructed without flipping. The 2D display device, the POL and the lens array rotate simultaneously to create a 360-degree continuous viewing zone by time division multiplexing. In our proposed tabletop 3D display system, the best viewing zone can be modulated to the lateral and the crosstalk caused by the narrow viewing angle can be eliminated. In addition, the proposed tabletop 3D display system is capable of reconstructing 3D images with both vertical and horizontal parallaxes. The experimental results agree well with the basic principle of the proposed method. [ABSTRACT FROM AUTHOR]

Highlights • A simple 3D calibration object is designed which can easily be observed by multiple cameras. • A correction method is proposed to minimum the error of reconstructed point clouds, improving the coincidence degree of point clouds in multiple angles. • The method proposed can calibrate all the cameras in one-pass calibration process. The operation is simple and convenient. • Correction is applied in 3D space instead of 2D space, the precision of point clouds is greatly improved. Abstract The single camera measurement system can't obtain all the surface information of the object limited by the field of view, thus it can't achieve complete measurement of the object. Multi-camera system can overcome this difficulty. But it is difficult to unify the coordinate system of distinct cameras. In order to solve this problem, a global calibration method of multi-camera system is proposed. A three-dimensional cube calibration object is designed. Every camera is only calibrated on one surface of the cube calibration object. Because different surfaces of the cube calibration object are in a unified world coordinate, the coordinates of the feature points on different surfaces are naturally in the unified world coordinate system. Thus global calibration can be completed by calibrating multiple cameras at the same time. In addition, to minimize the error of calibration, a correction method is proposed. The correction parameters are obtained by the deviation between the world coordinates and the reconstructed coordinates of the feature points on calibration object. The parameters are applied to the measurement to improve the accuracy of the whole point cloud. Experiments are carried out on a multi-camera measurement system, and the results show that the method proposed in this paper is effective and feasible. [ABSTRACT FROM AUTHOR]

Abstract: Today's trend in automotive displays is toward more, larger, better, and flexible panels. The requirements for cars differ largely from consumer displays: Automotive displays have unique requirements in terms of optical performance, longevity in harsh environment, and production of 100,000s per year per model. Consumer electronics displays, however, set the pace and premium automotive panels have to follow in short time because of customer expectations despite long development cycles. Advanced procedures and measurements have to be applied like lifetime and ambient light. In order to reduce the effort in specifying and evaluating car displays in terms of optical performance, the German Flat Panel Forum has set common requirements for automotive validation. As standard measurement procedures are often less suitable for automotive evaluation, dedicated methods were developed like Black Mura, gamma and visual assessment of anti‐glare surfaces. Standardization reduces the effort along the automotive display value chain. People in future autonomous cars will spend more time watching displays than today, which must then be of highest optical performance. Design visions trend to present information – and not displays – to driver and passengers, which includes seamless displays and smart surfaces. A simple integration of flat displays into dashboards is no longer state‐of‐the‐art. [ABSTRACT FROM AUTHOR]

We target the problem of sparse 3D reconstruction of dynamic objects observed by multiple unsynchronized video cameras with unknown temporal overlap. To this end, we develop a framework to recover the unknown structure without sequencing information across video sequences. Our proposed compressed sensing framework poses the estimation of 3D structure as the problem of dictionary learning, where the dictionary is defined as an aggregation of the temporally varying 3D structures. Given the smooth motion of dynamic objects, we observe any element in the dictionary can be well approximated by a sparse linear combination of other elements in the same dictionary (i.e., self-expression). Our formulation optimizes a biconvex cost function that leverages a compressed sensing formulation and enforces both structural dependency coherence across video streams, as well as motion smoothness across estimates from common video sources. We further analyze the reconstructability of our approach under different capture scenarios, and its comparison and relation to existing methods. Experimental results on large amounts of synthetic data as well as real imagery demonstrate the effectiveness of our approach. [ABSTRACT FROM AUTHOR]

Synthetic K + chabazite (KCHA), Cs + chabazite (CsCHA) and Zn 2+ chabazite (ZnCHA) have been synthesized and investigated in order to relate the differences in their crystalline structures to their thermal stability, moisture content and frequency dependent alternating current (AC) conductivity, permittivity and phase angle at a range of temperatures. The materials are shown to exhibit the universal dielectric response, which is typical of materials consisting of both conductive and insulating regions. Due to the presence of porosity, the three chabazites were hydrated significantly at room temperature and so the dehydrated state was achieved by heating the chabazites to high temperatures to ensure that all different energetic types of water were removed. Cation migration activation energies for KCHA (0.66 ± 0.10) eV, CsCHA (0.88 ± 0.01) eV and ZnCHA (0.90 ± 0.01) eV were determined during the cooling cycle from the fully dehydrated state to provide an accurate measurement of the activation energies. Good thermal stability of the materials was observed up to 710 °C and below 200 °C the electrical properties can be strongly influenced by hydration level. Overall, it was determined that when either hydrated or dehydrated, KCHA had the highest conductivity and lowest cation migration activation energy of the three studied chabazites and thus has the most promising electrical properties for potential use as a gas sensing material in next-generation electrical-based gas sensors. [ABSTRACT FROM AUTHOR]

The aim of this work was to assess handrim wheelchair propulsion effectiveness, related to the applied forces on the handrim, through the force feasible set. For a given posture of the upper-limb, it represents the set of isometric forces that can be applied on the handrim in any direction. The force feasible set was predicted from a musculoskeletal model of the upper-limb and trunk (10 degrees of freedom and 56 muscles). The aim of the first part of the study was to compare the force feasible set prediction and the force currently applied on the handrim. The second part proposes the creation of a new index called “Musculoskeletal Postural Performance Index” (MPPI) derived from the force feasible set and its comparison with the Mechanical Efficiency Force (MEF). These comparisons were conducted at 60, 80, 100, 120 and 140% of the Freely Chosen Frequency at submaximal and maximal conditions on 5 different phases of the push phase. The values of the MPPI were significantly correlated with those of the MEF. During the course of the push phase, the orientation of the force feasible set main axis approached that of the measured force and the force effectiveness evaluated through the MPPI increased. [ABSTRACT FROM AUTHOR]

3D shapes and 2D images usually contain complementary information for each other, and thus joint analysis of both of them will benefit some problems existing in different domains. Leveraging the connection between 2D images and 3D shapes, it's potential to mine lacking information of one modal from the other. Stemming from this insight, we design and implement a CNN architecture to jointly analyze shapes and images even with few training data guidance. The core of our architecture is a domain adaptation algorithm, which builds up the connection between underlying feature spaces of images and shapes, then aligns and correlates the intrinsic structures therein. The proposed method facilitates the recognition and retrieval tasks. Experiments on the shape recognition tasks show that our approach has superior performance under the difficult setting: zero-shot learning and few-shot learning. We also evaluate our method on the retrieval tasks, and demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

3D surface offsetting is a fundamental geometric operation in CAD/CAE/CAM. In this paper, we propose a super-linear convergent algorithm to generate a well-triangulated and feature-aligned offset surface based on particle system. The key idea is to distribute a set of moveable sites as uniformly as possible while keeping these sites at a specified distance away from the base surface throughout the optimization process. In order to make the final triangulation align with geometric feature lines, we use the moveable sites to predict the potential feature regions, which in turn guide the distribution of moveable sites. Our algorithm supports multiple kinds of input surfaces, e.g., triangle meshes, implicit functions, parametric surfaces and even point clouds. Compared with existing algorithms on surface offsetting, our algorithm has significant advantages in terms of meshing quality, computational performance, topological correctness and feature alignment. [ABSTRACT FROM AUTHOR]

Shape optimization often takes into account both inner and outer surfaces to achieve the design goals. The inner surface produced by existing methods is usually not support-free, which results in additional interior support structures during the printing process, thereby disrupting the design goals. In this paper, we present a simple and novel hollow-to-fill algorithm to guarantee the support-free property of inner surfaces for shape optimization. By analyzing the support-free conditions, three types of voxel-based support-free interior structures are proposed to compute inner surfaces. Given a voxelized model and the optimization goal, we first hollow out the model until it becomes a shell, whose thickness is determined by the physical material properties, and then add the support-free structures to optimize the inner surface, and finally refine the inner surface from bottom to top to minimize the optimization objective while maintaining the support-free property. Furthermore, shape deformation and extra weights are also utilized to optimize the shape for design goals. We demonstrate the feasibility and practicability of our method in three modes of balanced object design, where the physical mass properties of rigid objects are satisfied for the purpose of 3D printing. [ABSTRACT FROM AUTHOR]

The structure of a 3D model is essential for identifying and understanding of the object. A large number of models show hierarchical structures, which are not only efficient for shape characterization, but also applicable to structural/topological editing. However, how to construct the hierarchical structure is challenging. Most of the existing methods construct the hierarchical structure of a model based on the local relationships among parts. We propose Hierarchical Intrinsic Symmetry Structure (HISS) to represent the structure of models and an automatic construction approach. The analysis of intrinsic symmetry is based on the skeleton of the model. First, we extract skeletons of semantic parts of a model and construct skeleton graph. Next, we calculate the similarities among parts. Then, we employ a voting strategy to determine the hierarchical structure centers according to the intrinsic symmetry among similar part pairs. Finally, we construct the HISS based on the skeleton graph and the detected hierarchical centers. We evaluate the representation and the algorithm with a set of experiments and applications, including model set analysis, model repairing and model synthesis. [ABSTRACT FROM AUTHOR]

Given a single indoor image, this paper proposes an automatic retrieval system to estimate the best-matching 3D models with consistent style and pose. To support this system, we combine a deep CNN based object detection approach with a deformable part based alignment model. The key idea is to cast a 2D-3D alignment problem as a part-based cross-domain matching. We also provide an interactive refinement interface that allows users to browse models based on similarities and differences between shapes in user-specified regions of interest (ROIs). We demonstrate the ability of our system on numerous examples. [ABSTRACT FROM AUTHOR]

Recently, with the increased demand for low-power displays regarding portable devices, the RGBG PenTile display is popularly utilized. However, unlike the traditional RGB-stripe display with its three color channels, each pixel of the RGBG PenTile display comprises only two color channels, thereby causing the color leakage image distortion. To cope with this problem, most of the conventional methods employ a preprocessing filter for subpixel rendering; however, these filters cannot remove the color leakage completely, and they also result in the blurring artifacts. In this paper, a novel approach to obtain the preprocessing filter is presented. We formulate a filter design method as a minimum mean square error problem and derive an optimal preprocessing filter that is based on the human visual system (HVS) as follows; first, two perceived images indicating how human recognizes the images on the RGB and RGBG displays are generated and then the difference between the two perceived images is minimized to derive the optimal filter. In addition, in order to prevent the blurring artifact, the proposed filter is applied to the previously detected color-leakage region only. Experimental results demonstrate that the proposed method outperforms the conventional methods in terms of both the subjective and objective image quality. [ABSTRACT FROM AUTHOR]

Objective: Today's growing medical image databases call for novel processing tools to structure the bulk of data and extract clinically relevant information. Unsupervised hierarchical clustering may reveal clusters within anatomical shape data of patient populations as required for modern precision medicine strategies. Few studies have applied hierarchical clustering techniques to three-dimensional patient shape data and results depend heavily on the chosen clustering distance metrics and linkage functions. In this study, we sought to assess clustering classification performance of various distance/linkage combinations and of different types of input data to obtain clinically meaningful shape clusters. Methods: We present a processing pipeline combining automatic segmentation, statistical shape modeling, and agglomerative hierarchical clustering to automatically subdivide a set of 60 aortic arch anatomical models into healthy controls, two groups affected by congenital heart disease, and their respective subgroups as defined by clinical diagnosis. Results were compared with traditional morphometrics and principal component analysis of shape features. Results: Our pipeline achieved automatic division of input shape data according to primary clinical diagnosis with high F-score (0.902 ± 0.042) and Matthews correlation coefficient (0.851 ± 0.064) using the correlation/weighted distance/linkage combination. Meaningful subgroups within the three patient groups were obtained and benchmark scores for automatic segmentation and classification performance are reported. Conclusion: Clustering results vary depending on the distance/linkage combination used to divide the data. Yet, clinically relevant shape clusters and subgroups could be found with high specificity and low misclassification rates. Significance: Detecting disease-specific clusters within medical image data could improve image-based risk assessment, treatment planning, and medical device development in complex disease. [ABSTRACT FROM AUTHOR]

Current 3D crosstalk equation was defined from the characteristics of 3D display using glasses. This equation is not suitable for multi-view 3D display with larger view number as it gives the inappropriately large value. In 3D display using eyeglass, double images occur at large depth. But, in multi-view 3D display with larger view number, blur occurs to larger width for the larger depth. Hence, blur phenomenon of multi-view 3D display was investigated to understand the unique characteristics of multi-view 3D display. For this purpose, ray tracing S/W was used to simulate 3D display image seen at the designed viewing distance, to calculate the relative luminance distribution, and to quantify the relation between blur and depth. Calculated results showed that incomplete image separation caused the overlap of multiple view images and the blur. Blur edge width (BEW) was proportional to the horizontal disparity and related to the depth. BEWR = (BEW) / (binocular disparity) was newly defined, and its usefulness for 3D characterization was investigated. BEW and BEWR might be useful as new measuring items to characterize multi-view 3D display regarding 3D crosstalk. [ABSTRACT FROM AUTHOR]

Fish Tank Virtual Reality (FTVR) displays create a compelling 3D spatial effect by rendering to the perspective of the viewer with head-tracking. Combining FTVR with a spherical display enhances the 3D experience with unique properties of the spherical screen such as the enclosing shape, consistent curved surface, and borderless views from all angles around the display. The ability to generate a strong 3D effect on a spherical display with head-tracked rendering is promising for increasing user's performance in 3D tasks. An unanswered question is whether these natural affordances of spherical FTVR displays can improve spatial perception in comparison to traditional flat FTVR displays. To investigate this question, we conducted an experiment to see whether users can perceive the depth and size of virtual objects better on a spherical FTVR display compared to a flat FTVR display on two tasks. Using the spherical display, we found significantly that users had 1cm depth accuracy compared to 6.5cm accuracy using the flat display on a depth-ranking task. Likewise, their performance on a size-matching task was also significantly better with the size error of 2.3mm on the spherical display compared to 3.1mm on the flat display. Furthermore, the perception of size-constancy is stronger on the spherical display than the flat display. This study indicates that the natural affordances provided by the spherical form factor improve depth and size perception in 3D compared to a flat display. We believe that spherical FTVR displays have potential as a 3D virtual environment to provide better task performance for various 3D applications such as 3D designs, scientific visualizations, and virtual surgery. [ABSTRACT FROM AUTHOR]

With the rapid development of 3D technology, 3D model retrieval has attracted a large amount of interest in computer vision field. In this paper, we propose a composition-based multi-graph matching method in this paper. Firstly, compute the pairwise matching affinity one-to-one graph matching. Secondly, seek the optimal intermediate graph by diverse graph matching orders, according to the consistency of global matching. Finally, the classic optimization method is used to get the best matching result for similarity measurement. We validate our approach using ETH, NTU and MV-RED 3D model datasets with convolutional neural network features. Extensive experiments show the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

Immersive navigation in virtual reality (VR) and augmented reality (AR) leverages physical locomotion through pose tracking of the head-mounted display. While this navigation modality is intuitive, regions of interest in the scene may suffer from occlusion and require significant viewpoint translation. Moreover, limited physical space and user mobility need to be taken into consideration. Some regions of interest may require viewpoints that are physically unreachable without less intuitive methods such as walking in-place or redirected walking. We propose a novel approach for increasing navigation efficiency in VR and AR using multiperspective visualization. Our approach samples occluded regions of interest from additional perspectives, which are integrated seamlessly into the user's perspective. This approach improves navigation efficiency by bringing simultaneously into view multiple regions of interest, allowing the user to explore more while moving less. We have conducted a user study that shows that our method brings significant performance improvement in VR and AR environments, on tasks that include tracking, matching, searching, and ambushing objects of interest. [ABSTRACT FROM AUTHOR]

Autostereoscopic displays are likely to become widely used products in the future. However, certain physiological factors, especially visual comfort, limit their development. In this study, four observational parameters - ambient illuminance, image content, scaling ratio, and horizontal distance between major and minor objects - were evaluated to determine the degree of visual comfort offered by 3D computer-generated images on an autostereoscopic display. Visual comfort score with the range of 0-1 is designed to represent the degree of visual comfort for the 3D images with different manipulations of ambient illuminance, image content, scaling ratio, and horizontal distance between major and minor objects in this study. Subjects were asked to indicate images that produced discomfort. The proportion of images for each condition where participants indicated that viewing the image was comfortable was computed. Images receiving a proportion of 0.5 or greater were classified as acceptable. The disparity ranges over which acceptable images were attained for each participant and for each condition were analyzed with analysis of variance. The analytical results indicate that ambient illuminance and image content have a significant effect on the acceptable disparity range, while scaling ratio and horizontal distance between major and minor objects did not. [ABSTRACT FROM AUTHOR]

The quality of a 3-D geological model strongly depends on the type of integrated geological data, their interpretation and associated uncertainties. In order to improve an existing geological model and effectively plan further site investigation, it is of paramount importance to identify existing uncertainties within the model space. Information entropy, a voxel-based measure, provides a method for assessing structural uncertainties, comparing multiple model interpretations and tracking changes across consecutively built models. The aim of this study is to evaluate the effect of data integration (i.e., update of an existing model through successive addition of different types of geological data) on model uncertainty, model geometry and overall structural understanding. Several geological 3-D models of increasing complexity, incorporating different input data categories, were built for the study site Staufen (Germany). We applied the concept of information entropy in order to visualize and quantify changes in uncertainty between these models. Furthermore, we propose two measures, the Jaccard and the city-block distance, to directly compare dissimilarities between the models. The study shows that different types of geological data have disparate effects on model uncertainty and model geometry. The presented approach using both information entropy and distance measures can be a major help in the optimization of 3-D geological models. [ABSTRACT FROM AUTHOR]

Computerized route planning tools are widely used today by travelers all around the globe, while 3D terrain and urban models are becoming increasingly elaborate and abundant. This makes it feasible to generate a virtual 3D flyby along a planned route. Such a flyby may be useful, either as a preview of the trip, or as an after-the-fact visual summary. However, a naively generated preview is likely to contain many boring portions, while skipping too quickly over areas worthy of attention. In this paper, we introduce 3D trip synopsis: a continuous visual summary of a trip that attempts to maximize the total amount of visual interest seen by the camera. The main challenge is to generate a synopsis of a prescribed short duration, while ensuring a visually smooth camera motion. Using an application-specific visual interest metric, we measure the visual interest at a set of viewpoints along an initial camera path, and maximize the amount of visual interest seen in the synopsis by varying the speed along the route. A new camera path is then computed using optimization to simultaneously satisfy requirements, such as smoothness, focus and distance to the route. The process is repeated until convergence. The main technical contribution of this work is a new camera control method, which iteratively adjusts the camera trajectory and determines all of the camera trajectory parameters, including the camera position, altitude, heading, and tilt. Our results demonstrate the effectiveness of our trip synopses, compared to a number of alternatives. [ABSTRACT FROM AUTHOR]

This paper presents a method to reconstruct a functional mechanical assembly from raw scans. Given multiple input scans of a mechanical assembly, our method first extracts the functional mechanical parts using a motion-guided, patch-based hierarchical registration and labeling algorithm. The extracted functional parts are then parameterized from the segments and their internal mechanical relations are encoded by a graph. We use a joint optimization to solve for the best geometry, placement, and orientation of each part, to obtain a final workable mechanical assembly. We demonstrated our algorithm on various types of mechanical assemblies with diverse settings and validated our output using physical fabrication. [ABSTRACT FROM PUBLISHER]

Virtual Reality (VR) Head-Mounted Displays (HMDs) are on the verge of becoming commodity hardware available to the average user and feasible to use as a tool for 3D work. Some HMDs include front-facing cameras, enabling Augmented Reality (AR) functionality. Apart from avoiding collisions with the environment, interaction with virtual objects may also be affected by seeing the real environment. However, whether these effects are positive or negative has not yet been studied extensively. For most tasks it is unknown whether AR has any advantage over VR. In this work we present the results of a user study in which we compared user performance measured in task completion time on a 9 degrees of freedom object selection and transformation task performed either in AR or VR, both with a 3D input device and a mouse. Our results show faster task completion time in AR over VR. When using a 3D input device, a purely VR environment increased task completion time by 22.5 percent on average compared to AR ( p<0.024 ). Surprisingly, a similar effect occurred when using a mouse: users were about 17.3 percent slower in VR than in AR ( p<0.04 ). Mouse and 3D input device produced similar task completion times in each condition (AR or VR) respectively. We further found no differences in reported comfort. [ABSTRACT FROM AUTHOR]

If discrepancy between accommodation and convergence caused by a stereoscopic display exceeds fusion range of human eyes, viewers will see ghosting image, which leads to the loss of correct depth information and even causes severe visual fatigue. In this paper, an experiment aiming to investigate the binocular fusion range is conducted for a polarized 3D display. Two experimental trials are arranged to examine two aspects of fusion range including outward depth and inward depth. 3D modeling software is used to generate the test stereoscopic image pairs, which vary in depth by adjusting the separation between the virtual cameras. Angular parallax corresponding to the limit of fusion range is obtained by determining critical point of ghosting images. The experimental results show deviation between theoretical fusion range calculated by formula and experimental one.−0.223° to 0.275° represent critical fusion range for the polarized 3D display to avoid ghosting images. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) modelling and visualisation is one of the fastest growing application fields in geographic information science. 3D city models are being researched extensively for a variety of purposes and in various domains, including urban design, disaster management, education and computer gaming. These models typically depict urban business districts (downtown) or suburban residential areas. Despite informal settlements being a prevailing feature of many cities in developing countries, 3D models of informal settlements are virtually non-existent. 3D models of informal settlements could be useful in various ways, e.g. to gather information about the current environment in the informal settlements, to design upgrades, to communicate these and to educate inhabitants about environmental challenges. In this article, we described the development of a 3D model of the Slovo Park informal settlement in the City of Johannesburg Metropolitan Municipality, South Africa. Instead of using time-consuming traditional manual methods, we followed the procedural modelling technique. Visualisation characteristics of 3D models of informal settlements were described and the importance of each characteristic in urban design activities for informal settlement upgrades was assessed. Next, the visualisation characteristics of the Slovo Park model were evaluated. The results of the evaluation showed that the 3D model produced by the procedural modelling technique is suitable for urban design activities in informal settlements. The visualisation characteristics and their assessment are also useful as guidelines for developing 3D models of informal settlements. In future, we plan to empirically test the use of such 3D models in urban design projects in informal settlements. [ABSTRACT FROM AUTHOR]

While the viewing angle (VA) is an important parameter of three-dimensional (3-D) displays, a method has not yet been devised to determine the VA.We proposed a new approach to determine a VA of an integral imaging display. An integrated point appears at the cross section between collected rays and a lens array; the VA of the integrated point is thus equal to the angle between the two farthest rays. This approach is useful to determine the VA of all 3-D displays, because a 3-D point appears in the cross section of collected rays. The result of this study showed that the VA depends on the position of the integrated point and is smaller than the VA of the conventional calculation. [ABSTRACT FROM AUTHOR]

Single-voxel spectroscopy (SVS) is usually used in the pediatric population when a short acquisition time is crucial. To overcome the long acquisition time of 3-D phase-encoded chemical shift imaging (CSI) and lack of spatial coverage of single-voxel spectroscopy, efficient encoding schemes using spiral k-space trajectories have been successfully deployed, enabling acquisition of volumetric CSI in <5 min. We assessed feasibility of using 3-D spiral CSI sequence routinely in pediatric clinical settings by comparing its reconstructed spectra against SVS spectra. Volumetric spiral CSI obtained spectra from 2-cc isotropic voxels over a 16×16×10-cm region. SVS acquisition encoded a 3.4-cc (1.5-mm) isotropic voxel. Acquisition time was 3 min for every technique. Data were gathered prospectively from 11 random pediatric patients. Spectra from left basal ganglia were obtained using both techniques and were processed with post-processing software. The following metabolite ratios were calculated: N-acetylaspartate/creatine (NAA/Cr), choline/creatine (Cho/Cr), lactate/creatine (Lac/Cr) and N-acetylapartate/choline (NAA/Cho). We collected data on 11 children ages 4 days to 10 years. In 10/11 cases, spectral quality of both methods was acceptable. Considering 10/11 cases, we found a statistically significant difference between SVS and 3-D spiral CSI for all three ratios. However, this difference was fixed and was probably caused by a fixed bias. This means that 3-D spiral CSI can be used instead of SVS by removing the mean difference between the methods for each ratio. Accelerated 3-D CSI is feasible in pediatric patients and can potentially substitute for SVS. [ABSTRACT FROM AUTHOR]

Although autostereoscopic display is considered to be mainstream in the three-dimensional (3-D) display market for the near future, practical quality problems still exist due to various challenges such as the accommodation-vergence conflict and crosstalk. A number of studies have shown that these problems reduce the visual comfort and reliability of the perceived workload. We present two experiments for investigating the effect of parallax distribution, which affects the behavior of the accommodation and vergence responses and crosstalk on visual comfort in autostereoscopic display. We measured the subjective visual scores and perceived depth position for watching under various conditions that include foreground parallax, background parallax, and crosstalk levels. The results show that the viewers' comfort is significantly influenced by parallax distribution that induces a suitable conflict between the accommodation and vergence responses of the human visual system. Moreover, we confirm that crosstalk changes significantly affect visual comfort in parallax barrier autostereoscopic display. Consequently, the results can be used as guidelines to produce or adjust the 3-D image in accordance with the characteristics of parallax barrier autostereoscopic display. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate users' wayfinding task performance and subjective preference in a three-dimensional (3D) virtual environment. The research variables are interaction mode (touch sensitive vs body movement modes), viewing perspective [first-person perspective (1PP) versus third-person perspective (3PP)], and gender (man versus woman). Three difficult levels of tasks were conducted, i.e., A, A-P, and A-A types. The experiment is 2 × 2 × 2 between-subject design. Participants needed to complete three wayfinding tasks and fill out subjective preference questionnaires regarding task fluency, satisfaction, system usability scale, and NASA Task Load Index (NASA-TLX). Fifty-six participants (28 men and 28 women) were invited using convenient sampling method. The results are as follows: (1) Participants adopting touch-sensitive mode performed better than body movement mode. (2) Participants using touch-sensitive mode could have better task fluency and higher SUS score, and with less effort and frustration. (3) Participants adopting 3PP had better wayfinding task performance than first-person perspective. They also had higher system usability scale score and spent less effort for having wider viewing perspective. (4) The gender variable only showed significant effect in A-P type of wayfinding task. Men performed better than women. It is concluded that adopting touch-sensitive interaction and 3PP designs can better facilitate users' wayfinding tasks. [ABSTRACT FROM AUTHOR]

In observing the stereoscopic display at the viewing distance of 1 m, the amount of the perceived depth was determined by the positions of the crossing point that the viewing direction of two eyes intersect. The positions of the crossing points of stereoscopic stimuli were controlled, and the accommodation was measured by the autorefractometer for the seven participants. Accommodation was also measured when viewing the real film chart which was placed at the same position as these crossing points. The accommodation change when viewing the stereoscopic display was measured to be noticeable only when the crossing point was quite near the participant, but this change was still much smaller compared with the accommodation change when viewing the real film chart. This change in accommodation implies the possible occurrence of fatigue related to the accommodation-convergence conflict, while the constant accommodation within the range of DOF implies no conflict between the accommodation and convergence. This measurement scheme may be used to define the range of DOF where the accommodation remains little changed, and thus define the depth of the 3D object at which no accommodation-convergence conflict occurs, for a given stereoscopic display. [ABSTRACT FROM AUTHOR]

In order to investigate visual experience for watching the autostereoscopic three-dimensional (3D) projection display, we conduct a subjective evaluation experiment by a questionnaire when viewing video clips. Factor analysis is adopted to classify the evaluation items for the perpetual constructs of visual experience. Then a mixed design with repeated measurement analysis of variance with dimension and display duration as factors is carried out on the evaluation data to check the factorial effects and interactions for statistical significance. The results of factor analysis extract five factors including visual comfort, image quality, distortion, naturalness, and presence, which can be used as comprehensive indicators to evaluate the autostereoscopic 3D projection display. The results of analysis of variance indicate that image quality, which is used to assess two-dimensional contents, is no longer applicable. It is necessary to give consideration to depth when evaluating 3D visual experience. Although 3D scenes enhance the overall subjective performance such as naturalness and presence, the health issues and stereoscopic distortion related to the introduction of depth cannot be ignored. [ABSTRACT FROM AUTHOR]

Pickup method adopting the modified algorithm to generate the elemental image from virtual objects is proposed to obtain the elemental image for real objects. In the proposed method, the number of capturing processes is reduced compared with the conventional multiple capturing method. The pseudoscopic image problem can be resolved by controlling the position and the direction of the imaging device in the proposed pickup system. The telecentric lens system is used to capture the orthographic scenes, which are divided and compounded into the elemental image. The validity of the proposal is proved by the experimental results of the pickup and the reconstruction. [ABSTRACT FROM AUTHOR]

Twelve participants were tested on a simple virtual object precision placement task while viewing a stereoscopic three-dimensional (S3-D) display. Inclusion criteria included uncorrected or best corrected vision of 20/20 or better in each eye and stereopsis of at least 40 arc sec using the Titmus stereotest. Additionally, binocular function was assessed, including measurements of distant and near phoria (horizontal and vertical) and distant and near horizontal fusion ranges using standard optometric clinical techniques. Before each of six 30 min experimental sessions, measurements of phoria and fusion ranges were repeated using a Keystone View Telebinocular and an S3-D display, respectively. All participants completed experimental sessions in which the task required the precision placement of a virtual object in depth at the same location as a target object. Subjective discomfort was assessed using the simulator sickness questionnaire. Individual placement accuracy in S3-D trials was significantly correlated with several of the binocular screening outcomes: viewers with larger convergent fusion ranges (measured at near distance), larger total fusion ranges (convergent plus divergent ranges, measured at near distance), and/or lower (better) stereoscopic acuity thresholds were more accurate on the placement task. No screening measures were predictive of subjective discomfort, perhaps due to the low levels of discomfort induced. [ABSTRACT FROM AUTHOR]

Face completion is a domain-specific image inpainting problem. Most existing face completion methods fail to synthesize fine-grained facial structures due to the undifferentiated treatment of face images and other scene images. To handle this problem, we propose an end-to-end deep generative model based approach which makes full use of the facial prior knowledge, including 2D facial geometry priors from facial parsing maps and landmarks, as well as the 3D depth prior. We adopt a coarse-to-fine inpainting framework where the 2D facial geometry priors based on coarse faces are extracted to guide the refinement network for better planar facial textures and structures. Moreover, a novel 3D regularized reconstruction loss is proposed for the enhancement of the stereo perception of generated faces. Experimental results on two large-scale benchmarks CelebA and CelebA-HQ show that our method significantly outperforms the state-of-the-arts in generating more visually realistic and pleasing faces. Code is available at. • A face completion network with both 2D and 3D facial priors is designed. • The 2D geometry priors composed of facial parsing maps and landmarks are proposed. • A novel 3D regularized construction loss is designed for better stereo perception. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the visual fatigue of integral imaging three-dimensional (3D) display by studying the accommodation and convergence when viewing the integral imaging 3D images. The theoretical analyses show that there is no inconsistency between the accommodation and convergence distances, which means that the integral imaging 3D display has no visual fatigue. Experiments are implemented, and the results finally demonstrate the rationality of the theoretical analyses. These analyses can be quite beneficial for researchers to better understand the performances and promote the practical applications of the integral imaging 3D display. [ABSTRACT FROM AUTHOR]

A complete large scale city map which enables access to geometric as well as visual information is required by most organizations. There exist a number of problems such as moving the vehicle, moving objects and occlusions which affect the development of such maps. In this regard, the use of stereo panoramas is an image based solution which has attracted the developers and users of city maps. This is due to the fact that stereo panoramas' besides offering a visual and complete view of surrounding static and moving are simple to create. There exist a number of techniques which are used to develop stereo panoramas. This paper, reviews these techniques from the projection as well as the geometrical stand points. The review includes systems offered for image acquisition, stereo panorama generation, registration, geometric measurement and representation. [ABSTRACT FROM AUTHOR]