Opacity volume based halo generation and depth-dependent halos

Halos are generally used to enhance depth perception and display spatial relationships in illustrative visualization. In this paper, we present a simple and effective method to create volumetric halo illustration. At the preprocessing stage, we generate, on graphics hardware, a view-independent halo intensity volume, which contains all of the potential halos around the boundaries of features, based on the opacity volume. During halo rendering, the halo intensity volume is used to extract halos only around the contours of structures for the current viewpoint. The performance of our approach is significantly faster than previous halo illustration methods, which perform both halo generation and rendering during direct volume rendering. We further propose depth-dependent halo effects, including depth color fading and depth width fading. These halo effects adaptively modulate the visual properties of halos to provide more perceptual cues for depth interpretation. Experimental results demonstrate the efficiency of our proposed approach and the effectiveness of depth-dependent halos.     

GPU Accelerated Direct Volume Rendering on an Interactive Light Field Display

We present a GPU accelerated volume ray casting system interactively driving a multi‐user light field display. The display, driven by a single programmable GPU, is based on a specially arranged array of projectors and a holographic screen and provides full horizontal parallax. The characteristics of the display are exploited to develop a specialized volume rendering technique able to provide multiple freely moving naked‐eye viewers the illusion of seeing and manipulating virtual volumetric objects floating in the display workspace. In our approach, a GPU ray‐caster follows rays generated by a multiple‐center‐of‐projection technique while sampling pre‐filtered versions of the dataset at resolutions that match the varying spatial accuracy of the display. The method achieves interactive performance and provides rapid visual understanding of complex volumetric data sets even when using depth oblivious compositing techniques.     

脑血管体绘制的快速表意式增强

利用3维可视化技术重构脑血管模型,获取脑血管及其相关组织的立体结构,对于辅助诊断脑血管疾病具有重要意义.鉴于脑血管位置的特殊性、形态的复杂性及灰度信息的多变性,要求重构技术能够清晰还原其空间结构.基于CUDA(computed unified device architecture)的光线投射体绘制,引入深度和轮廓宽度等因子,采用基于曲率的轮廓增强、基于深度的边界增强以及基于立体显示和颜色融合的深度线索提示等表意式技术,实时重构高质量3维血管模型,生动展现脑血管的3维结构信息,如深度、梯度、观察方向等.实验结果表明,本文方法的有效性,在精确显示脑血管结构的同时能够增强体绘制效果.     

Smaller and bigger displays

This chapter describes the small displays of cell phones and the large screens of high definition digital televisions. The most difficult ergonomic design point of the cell phone is to pack the display and keyboard into the small volume. The design method described is one example of Japanese miniaturization technology. This chapter describes the metrics of cell phone display performance and then introduces the studies that experimentally determined the display performance requirements. Lastly, technical trends in plasma display panels are discussed.     

Analytical model for three-dimensional light-field displays based on voxel construction

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.     

基于等高线的三维地形造型算法

提出了一个从等高线地形图转换成三维真实感地形显示的快速算法，给出用深度标记法求出各点地形高度的插值算法，并对三维造型的快速显示作了探讨。实验证明本文造型方法速度快、精度高。     

Depth Averaged Modelling of Turbulent Shallow Water Flow with Wet-Dry Fronts

Depth averaged models are widely used in engineering practice in order to model environmental flows in river and coastal regions, as well as shallow flows in hydraulic structures. This paper deals with depth averaged turbulence modelling. The most important and widely used depth averaged turbulence models are reviewed and discussed, and a depth averaged algebraic stress model is presented. A finite volume model for solving the depth averaged shallow water equations coupled with several turbulence models is described with special attention to the modelling of wet-dry fronts. In order to asses the performance of the model, several flows are modelled and the numerical results are compared with experimental data.     

Direct visualization of volume data

A combination of segmentation tools and fast volume renderers that provides an interactive exploration environment for volume visualization is discussed. The tools and renderers include mechanisms that distribute volume data across multiple processors, as well as image compositing techniques and solutions to representation problems in the selection and display of subregions within bounding volumes. A volume visualization technique using the interactive control of images rendered directly from volume data coupled with a user-controlled semantic classification tool is described. The variations of parallel volume rendering being explored on the Pixel-Planes 5 system and the region-of-interest selection methods and the interactive tools used by the system are presented. The flexibility and power of combining volume rendering with region-of-interest selection techniques are demonstrated using examples of medical imaging applications     

Evaluation of true 3 D display systems for visualizing medical volume data

The last few years have witnessed extraordinary advances in medical imaging. The new digital methods, such as CT or MRI, share the common characteristic of providing three-dimensional volume data. The urgent need for efficient techniques for visualizing volume data has recently been recognized not only in diagnostic medicine, but also in computer-assisted surgery and radiation-therapy planning. In recent years, new display technologies have emerged, in which depth perception has been improved significantly, because it relies in principle on physiological depth cues. This paper presents the state-of-theart is true 3D displays (with a special emphasis placed on equipment that has reached relative maturity) and a discussion of their most important advantages and disadvantages with respect to visualizing medical data.     

Visualization of 3D ultrasound data

It is suggested that ultrasound data acquisition will play an increasing role in the future of medical imaging. Unlike magnetic resonance imaging (MRI) and computerized tomography (CT), ultrasound offers interactive visualization of underlying anatomy in real time. Additionally, ultrasound equipment costs far less and does not use ionizing radiation or require specialized facilities. The different methods for multidimensional medical imaging and scientific visualization are reviewed. Several volume visualization algorithms are discussed. They are multiplexer slicing, surface fitting, volume rendering, data classification, and viewing and shading. Three-dimensional ultrasound data display methods are also discussed     

履带式机器人虚拟控制平台的研究与设计

针对目前多履带机器人运动规律的探索难以深入和运动效果的展示难以实现等问题,研究并设计了一种基于虚拟实现技术而建立的履带式机器人控制交互展示平台;结合该辅助平台的建立过程,探讨了履带式机器人的虚拟遥操作技术,以及其虚拟显示与实际控制的同步性问题,提出了履带式机器人构建接触模型的处理方法,给出了其虚拟端运动学仿真以及相关的数学模型,使得平台控制可以借助于虚拟的反馈为依据;所讨论的设计方法和技术途径可为构建和开发其他相似的仿真平台提供参考和借鉴。     

Improvement of 3D visual image quality by using high frame rate

The relationship between high frame rate and depth perception was investigated. Psychophysical experiments using moving random dot stereograms to study depth discrimination under several conditions showed that three‐dimensional motion images produced and displayed with a frame rate of 240 fps enable finer discrimination of depth for the viewer compared with frame rates of 120 or 60 fps. In addition, overall evaluations of natural three‐dimensional motion images by viewers confirmed that more natural motion and depth impressions were presented at 240 fps than at lower frame rates. Further, the results are discussed with reference to a recent theoretical model of the dynamic spatial frequency response of the camera/display system.     

Wide-baseline view synthesis for light-field display based on plane-depth-fused sweep volume

The advancements in three-dimensional (3D) display technology have led to a wide interest in light-field display. However, the need to simultaneously capture a large number of object views made content generation for light-field displays still a bottleneck. In this paper, we propose a method for light-field content generation based on plane-depth-fused sweep volume (PDFSV), focusing on handling wide-baseline views and exhibiting scene generalization when the camera array remains unchanged. Specifically, the proposed PDFSV exploits the prior depth of the images captured by a 4 × 4 spherical camera array to represent 3D information of scenes. Then two optimized sequential convolutional neural networks (CNN) are employed for implicit depth modeling and final color calculation, respectively. By doing these, the prior depth facilitates the synthesis of regions with complex textures in the target view. We produce a Wide-baseline Multi-view Image Set (WMIS) which has a field of view (FOV) angle reaching 54°and could be publicly available for access. In our experiments, we use only the 4 vertex views as input. Results demonstrate that the proposed approach can synthesize high-quality views at arbitrary positions between sparse views, outperforming existing neural-radiance-fields-based (NeRF-based) methods. Finally, we conduct autostereoscopic display experiments, achieving satisfactory results.     

2维至3维图像/视频转换的深度图提取方法综述

目的 深度图提取是计算机视觉领域的研究热点。随着3D显示设备的普及,2D-3D图像/视频转换的深度图提取研究受到越来越多国内外学者的关注。为此回顾深度图提取研究历程,并对已有成果进行分类、概括和评述。方法 由于深度图提取方法的实现主要依赖于深度线索,不同方法存在人机交互程度上的差异。采用基于深度线索和基于人机交互程度的两种分类方法进行归纳评述。结果 根据深度线索的不同,将深度图提取方法分为基于单目线索的方法、基于双目线索的方法和基于混合线索的3类方法。然后从人机交互的角度,将深度图提取方法分为人工法、半自动法和全自动法。介绍了这些方法的基本思想,比较归纳不同方法的优点与不足。最后,阐述了近年来热门的机器学习方法在深度图提取的应用。结论 对深度图提取研究进行简要的总结和展望。指出深度图提取研究具有从研究热点中挖掘创新思路、引入新的深度线索等发展趋势。     

New 3-D display that can display 3-D images at long distances and that can control their 3-D positions using changing size as a cue to depth perception

This paper presents a new three-dimensional (3-D) display that can display 3-D images at long distances of tens or hundreds of meters in the depth direction and that can control their 3-D positions to meet new requirements for outdoor use. The proposed display uses changing size as a cue to depth perception, i.e., the smoothly expanding motion of virtual images formed with optical systems according to the forward movements of the users to display 3-D images at more distant positions in the depth direction than positions where virtual images are formed with optical systems because conventional 3-D displays that use binocular disparity are only able to display 3-D images at short distances in the depth direction. The feasibility of the proposed display was evaluated by subjective tests using a moving minivan in which observers viewed a test pattern that overlapped the real view ahead of the automobile observed through the windshield. The results obtained from the subjective tests revealed that the test pattern was observed at long distances over tens and hundreds of meters in the depth direction and that the position in the depth direction of the test pattern could be controlled by changing the rate at which the motion of the test pattern smoothly expanded. These results demonstrated that the proposed display was feasible.     

Displaying of details in subvoxel accuracy

Under the volume segmentation in voxel space,a lot of details,some fine and thin objects,are ignored.In order to accurately display these details,this paper has developed a methodology for volume segmentation in subvoxel space.In the subvoxel space,most of the “bridges”between adjacent layers are broken down.Based on the subvoxel space,an automatic segmentation algorithm reserving details is discussed.After segmentation,volume data in subvoxel space are reduced to original voxel space.Thus,the details with width of only one or several voxels are extracted and displayed.     

A preliminary investigation of the time tunnels display design technique

Two forms of decision support were evaluated using a simulated process control task environment. The time tunnel display design concept provides temporal (historical) information about the value of variables and relationships over time using perspective geometry and the depth plane. The compensated level variable is a quickened display that provides estimates of system state that is not confounded by counter-intuitive and time-delayed thermodynamic effects. These two forms of decision support were applied factorially (present, absent) to produce four experimental conditions. The results for system control and fault detection tasks indicate that display quickening improved performance significantly while the time tunnel displays did not. The results for data extraction tasks (reporting the values of system variables) were dependent upon the quality of the mapping between properties in the domain and visual features in the display. Methodological factors that may have influenced the results are considered and subsequent evaluations of the time tunnels design technique, using alternative methodologies, are discussed. It is concluded that the time tunnels display design concept has potential as a form of decision support and is worthy of additional research efforts.     

Binocular vision in a bi-ocular world: new-generation head-mounted displays avoid causing visual deficit

Our previous research highlighted adverse visual effects after wearing a binocular head-mounted display (HMD) for a 10 min stereoscopic visualization task. We have since proposed a theoretical, explanation based on the conflict between the depth. Such cues presented by image disparity and image focal depth. Such conflict, however, is not evident in all HMD configurations, and we replicated our early trials using a new-generation bi-ocular HMD produced by Virtuality Entertainment Ltd. Using similar, conventional optometric procedures with 50 participants, we observed no problems in the use of this display for immersion periods of to 30 min. This study demonstrates that effective HMDs can be produced through careful design and precision engineering. It also suggests a difference between the presentation of binocular and bi-ocular images and the requirements that they place on the visual system. Factors to consider in the future development of binocular displays are discussed.     

Using stereokinetic effect to convey depth: computationally efficient depth-from-motion displays.

Recent developments in microelectronics have encouraged the use of 3D data bases to create compelling volumetric renderings of graphical objects. However, even with the computational capabilities of current-generation graphical systems, real-time displays of such objects are difficult, particularly when dynamic spatial transformations are involved. In this paper we discuss a type of visual stimulus (the stereokinetic effect display) that is computationally far less complex than a true three-dimensional transformation but yields an equally compelling depth impression, often perceptually indiscriminable from the true spatial transformation. Several possible applications for this technique are discussed (e.g., animating contour maps and air traffic control displays so as to evoke accurate depth percepts).