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沉浸式环境中多场景视觉提示信息可视化方法综述

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中国图象图形学报 2024年第1期29卷 1-21页

作者：任洋甫李志强张松海青海大学计算机技术与应用系西宁810016 清华大学计算机科学与技术系北京100084 国防大学联合作战学院北京100091

沉浸式环境是通过虚拟现实(virtual reality,VR)等技术为用户呈现趋近于真实的环境体验。虚拟现实是通过计算机生成现实世界的模拟环境,可以为用户提供丰富的沉浸感、交互性和想象力体验。用户在虚拟现实场景中,通过视觉可以快速熟悉环... 详细信息

沉浸式环境是通过虚拟现实(virtual reality,VR)等技术为用户呈现趋近于真实的环境体验。虚拟现实是通过计算机生成现实世界的模拟环境,可以为用户提供丰富的沉浸感、交互性和想象力体验。用户在虚拟现实场景中,通过视觉可以快速熟悉环境,获取场景内外的信息,还可以通过视觉完成与场景的交互,增强用户的感知。增强现实(augmented reality,AR)会将虚拟信息放置在真实场景中,用户可以与真实场景中的虚拟信息进行交互。为了充分了解视觉提示信息在虚拟现实等不同沉浸式场景中的研究,探究视觉信息提示方法的本源,本文按照信息提示位置的不同、功能和应用的不同进行区分,首先综述近年来在普通二维场景中的方法,通过技术对比和改进深入讨论了在三维虚拟现实或增强现实环境下对视觉提示信息可视化方法的研究。分析在虚拟现实或增强现实环境下与普通二维场景中显示的异同,同时展开视觉提示信息在多场景下对用户注意力等使用功能方面的研究介绍,以及全景视频观看等实际场景中的应用研究说明。本文通过对二维和三维场景视野外、场景中标签布局和注意力引导,以及全景视频观看等实际应用中的讨论,可以更详细地展示视觉提示信息在沉浸式环境和多场景中的研究前景与发展方向。

关键词：沉浸式环境虚拟现实(VR) 增强现实(AR) 多场景视觉提示信息全景视频注意力引导

A Survey on Multiview Video Synthesis and Editing

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Tsinghua Science and Technology 2016年第6期21卷 678-695页

作者： Shaoping Lu Taijiang Mu songhai zhang the Department of Electronics and Informatics (ETRO) Vrije Universiteit Brussel (VUB) the TNList Tsinghua University

Multiview video can provide more immersive perception than traditional single 2-D video. It enables both interactive free navigation applications as well as high-end autostereoscopic displays on which multiple users can perceive genuine 3-D content without glasses. The multiview format also comprises much more visual information than classical 2-D or stereo 3-D content, which makes it possible to perform various interesting editing operations both on pixel-level and object-level. This survey provides a comprehensive review of existing multiview video synthesis and editing algorithms and applications. For each topic, the related technologies in classical 2-D image and video processing are reviewed. We then continue to the discussion of recent advanced techniques for multiview video virtual view synthesis and various interactive editing applications. Due to the ongoing progress on multiview video synthesis and editing, we can foresee more and more immersive 3-D video applications will appear in the future.

关键词： multiview video view synthesis video editing color correction survey

New advances in visual computing for intelligent processing of visual media and augmented reality

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Science China(Technological Sciences) 2015年第12期58卷 2210-2211页

作者： WANG JuHong zhang songhai MARTIN Ralph R. Department of Computer Science and Technology Tsinghua University School of Computer Science & Informatics Cardiff University

Visual imagery constitutes the most important sensory information for *** entire field of acquiring,analyzing and synthesizing visual data by means of computers is called visual *** has an extraordinarily wide range of applications,including for example:industrial quality control,street view and driver assistance systems,robot navigation,multimedia systems,and computer games.

关键词： Augmented reality Intelligent computing

Traffic signal detection and classification in street views using an attention model

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Computational Visual Media 2018年第3期4卷 253-266页

作者： Yifan Lu Jiaming Lu songhai zhang Peter Hall TNList Tsinghua University Department of Computer Science University of Bath

Detecting small objects is a challenging *** focus on a special case:the detection and classification of traffic signals in street *** present a novel framework that utilizes a visual attention model to make detection more efficient,without loss of accuracy,and which *** attention model is designed to generate a small set of candidate regions at a suitable scale so that small targets can be better located and *** order to evaluate our method in the context of traffic signal detection,we have built a traffic light benchmark with over 15,000 traffic light instances,based on Tencent street view *** have tested our method both on the dataset we have built and the Tsinghua–Tencent 100K(TT100K)traffic sign *** show that our method has superior detection performance and is quicker than the general faster RCNN object detection framework on both *** is competitive with state-of-theart specialist traffic sign detectors on TT100K,but is an order of magnitude *** show generality,we tested it on the LISA dataset without tuning,and obtained an average precision in excess of 90%.

关键词： traffic light detection traffic light benchmark small object detection CNN

Locomotion perception and redirection

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Virtual Reality & Intelligent Hardware 2021年第6期3卷 I0003-I0004页

作者： Miao WANG songhai zhang Shimin HU State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100191China Department of Computer Science and Technology Tsinghua UniversityBeijing 100084China

Locomotion is a fundamental interaction technique that allows free navigation in virtual scenes.A large body of literature has demonstrated that natural locomotion experience can significantly improve the sense of presence and help users achieve better performance in tasks such as searching and *** the upcoming metaverse era,locomotion will play a critical role in the success of large-scale interactive *** and redirection are two tightly connected problems in virtual *** a limited physical condition and a target virtual scene,how to make the perceived locomotion as natural as possible,and further unknowingly redirect the user in the physical world is an open *** this special issue,we have selected five papers that provide their latest updates for research problems of view control,virtual jumping,climbing,and searching.

关键词： redirect interactive motion

Video-based running water animation in Chinese painting style

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Science in China(Series F) 2009年第2期52卷 162-171页

作者： zhang songhai CHEN Tao zhang YiFei HU ShiMin MARTIN Ralph Department of Computer Science and Technology Tsinghua University Beijing 100084 China School of Computer Science Cardiff University 5 The Parade Roath Cardiff Wales CF24 3AA UK

This paper presents a novel algorithm for synthesizing animations of running water, such as water- falls and rivers, in the style of Chinese paintings, for applications such as cartoon making. All video frames are first registered in a common coordinate system, simultaneously segmenting the water from background and computing optical flow of the water. Taking artists＇ advice into account, we produce a painting structure to guide painting of brush strokes. Flow lines are placed in the water following an analysis of variance of optical flow, to cause strokes to be drawn where the water is flowing smoothly, rather than in turbulent areas： this allows a few moving strokes to depict the trends of the water flows. A variety of brush strokes is then drawn using a template determined from real Chinese paintings. The novel contributions of this paper are： a method for painting structure generation for flows in videos, and a method for stroke placement, with the necessary temporal coherence.

关键词： non-photorealistic rendering Chinese painting stroke based rendering video rendering optical flow

Practical automatic background substitution for live video

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Computational Visual Media 2017年第3期3卷 273-284页

作者： Haozhi Huang Xiaonan Fang Yufei Ye songhai zhang Paul L.Rosin Department of Computer Science Tsinghua University School of Computer Science and Informatics Cardiff University

In this paper we present a novel automatic background substitution approach for live video. The objective of background substitution is to extract the foreground from the input video and then combine it with a new background. In this paper, we use a color line model to improve the Gaussian mixture model in the background cut method to obtain a binary foreground segmentation result that is less sensitive to brightness differences. Based on the high quality binary segmentation results, we can automatically create a reliable trimap for alpha matting to refine the segmentation boundary. To make the composition result more realistic, an automatic foreground color adjustment step is added to make the foreground look consistent with the new background. Compared to previous approaches, our method can produce higher quality binary segmentation results, and to the best of our knowledge, this is the first time such an automatic and integrated background substitution system has been proposed which can run in real time, which makes it practical for everyday applications.

关键词： background substitution background replacement background subtraction alpha matting

Detection of scene-irrelevant head movements via eye-head coordination information

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Virtual Reality & Intelligent Hardware 2021年第6期3卷 501-514页

作者： Xiaoxiong FAN Yun CAI Yufei YANG Tianxing XU Yike Li songhai zhang Fanglue zhang Tsinghua University Beijing 100084China Victoria University of Wellington WellingtonNew Zealand

Background Accurate motion tracking in head-mounted displays(HMDs)has been widely used in immersive VR interaction ***,tracking the head motion of users at all times is not always *** a session of HMD usage,users may make scene-irrelevant head rotations,such as adjusting the head position to avoid neck pain or responding to distractions from the physical *** the best of our knowledge,this is the first study that addresses the problem of scene-irrelevant head *** We trained a classifier to detect scene-irrelevant motions using temporal eye head-coordinated information *** investigate the usefulness of the detection results,we propose a technique to suspend motion tracking in HMDs where scene-irrelevant motions are ***/Conclusions Experimental results demonstrate that the scene-relevancy of movements can be detected using eye-head coordination information,and that ignoring scene-irrelevant head motions in HMDs improves user continuity without increasing sickness or breaking immersion.

关键词： Virtual reality Human-centered computing Human-computer interaction(HCI) Interaction paradigms HCI design and evaluation methods User models

Fast portrait automatic segmentation with coarse-to-fine CNNs

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Computer Aided Drafting,Design and Manufacturing 2017年第2期27卷 39-49页

作者： zhang Xijin Li Ruilong zhang songhai Department of Computer Science and Technology Tsinghua University

In this paper, we propose a coarse-to-fine convolutional network framework designed with problem specific knowledge for fast automatic portrait segmentation. We built up a dataset of 7 100 portrait images which are frames from personal live show videos. The proposed network includes a coarse network which can learn global information and a fine network which utilizes local information to refine the coarse output. Additionally, an auxiliary contour loss is introduced to help training the coarse network. The proposed framework shows higher accuracy than the widely-used fully convolutional network. With light-weight post-processing, the predicted foreground mask can be used in real-time portrait video editing tasks such as background replacement.

关键词： convolutional neural network image segmentation machine learning