检索结果-南通市图书馆

Video-based running water animation in Chinese painting style

在线全文

学校读者我要写书评

暂无评论

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

Skeleton-based canonical forms for non-rigid 3D shape retrieval

在线全文

学校读者我要写书评

暂无评论

Computational Visual Media 2016年第3期2卷 231-243页

作者： David Pickup Xianfang Sun Paul L.Rosin ralph R.martin School of Computer Science and Informatics Cardiff University

The retrieval of non-rigid 3D shapes is an important task. A common technique is to simplify this problem to a rigid shape retrieval task by producing a bending-invariant canonical form for each shape in the dataset to be searched. It is common for these techniques to attempt to "unbend" a shape by applying multidimensional scaling(MDS) to the distances between points on the mesh, but this leads to unwanted local shape distortions. We instead perform the unbending on the skeleton of the mesh, and use this to drive the deformation of the mesh itself. This leads to computational speed-up, and reduced distortion of local shape detail. We compare our method against other canonical forms: our experiments show that our method achieves state-of-the-art retrieval accuracy in a recent canonical forms benchmark, and only a small drop in retrieval accuracy over the state-of-the-art in a second recent benchmark, while being significantly faster.

关键词： canonical forms shape retrieval skeletons pose invariance

Can attention enable MLPs to catch up with CNNs?

在线全文

学校读者我要写书评

暂无评论

Computational Visual Media 2021年第3期7卷 283-288页

作者： Meng-Hao Guo Zheng-Ning Liu Tai-Jiang Mu Dun Liang ralph R.martin Shi-Min Hu BNRist Department of Computer Science and TechnologyTsinghua UniversityBeijing 100084China Cardiff University Cardiff CF243AAUK.

In the first week of May 2021,researchers from four different institutions:Google,Tsinghua University,Oxford University,and Facebook shared their latest work[1–4]on ar *** at almost the same time,each proposing new learning architectures,consisting mainly of linear layers,claiming them to be comparable or superior to convolutional-based models.

关键词： enable Facebook Google

PCT:Point cloud transformer

在线全文

学校读者我要写书评

暂无评论

Computational Visual Media 2021年第2期7卷 187-199页

作者： Meng-Hao Guo Jun-Xiong Cai Zheng-Ning Liu Tai-Jiang Mu ralph R.martin Shi-Min Hu BNRist Department of Computer Science and TechnologyTsinghua UniversityBeiing 100084China Cardiff University Cardiff CF243

The irregular domain and lack of ordering make it challenging to design deep neural networks for point cloud *** paper presents a novel framework named Point Cloud Transformer(PCT)for point cloud *** is based on Transformer,which achieves huge success in natural language processing and displays great potential in image *** is inherently permutation invariant for processing a sequence of points,making it well-suited for point cloud *** better capture local context within the point cloud,we enhance input embedding with the support of farthest point sampling and nearest neighbor *** experiments demonstrate that the PCT achieves the state-of-the-art performance on shape classification,part segmentation,semantic segmentation,and normal estimation tasks.

关键词： 3D computer vision deep learning point cloud processing Transformer

Expressive line drawings of human faces from range images

在线全文

学校读者我要写书评

暂无评论

Science in China(Series F) 2009年第2期52卷 295-307页

作者： HUANG YueZhu martin ralph R. ROSIN Paul L. MENG XiangXu YANG ChengLei Department of Computer Science and Technology Shandong University Jinan 250101 China School of Computer Science Cardiff University Cardiff United Kingdom

We propose a novel technique to extract features from a range image and use them to produce a 3D pen-and-ink style portrait similar to a traditional artistic drawing. Unlike most previous template-based, component-based or example-based face sketching methods, which work from a frontal photograph as input, our system uses a range image as input. Our method runs in real-time for models of moderate complexity, allowing the pose and drawing style to be modified interactively. Portrait drawing in our system makes use of occluding contours and suggestive contours as the most important shape cues. However, current 3D feature line detection methods require a smooth mesh and cannot be reliably applied directly to noisy range images. We thus present an improved silhouette line detection algorithm. Feature edges related to the significant parts of a face are extracted from the range image, connected, and smoothed, allowing us to construct chains of line paths which can then be rendered as desired. We also incorporate various portrait-drawing principles to provide several simple yet effective non- photorealistic portrait renderers such as a pen-and-ink shader, a hatch shader and a sketch shader. These are able to generate various life-like impressions in different styles from a user-chosen viewpoint. To obtain satisfactory results, we refine rendered output by smoothing changes in line thickness and opacity. We are careful to provide appropriate visual cues to enhance the viewer＇s comprehension of the human face. Our experimental results demonstrate the robustness and effectiveness of our approach, and further suggest that our approach can be extended to other 3D geometric objects.

关键词： portrait drawing non-photorealistic rendering line drawing suggestive contour occluding contour feature line stylization

Painting patches:Reducing flicker in painterly re-rendering of video

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2011年第12期 2612-2621页

作者： martin ralph School of Computer Science and Informatics Cardiff University Cardiff Wales CF24 3AA UK

This paper presents a novel method for re-rendering video in a stroke-based painterly style. Previous methods typically place and adjust strokes on a frame by frame basis, guided by an analysis of motion vectors. Our method constructs painting patches which last for multiple frames, and paints them just once, compositing them after placing and clipping each one in each output frame. Painting patches are constructed by clustering pixels with similar motions, representing moving objects. This is done using a multi-frame window, to take account of objects which are present in consecutive frames, and which may occur a few frames apart with occlusion. The appearance of a given cluster across a sequence of frames is warped to a common reference to produce the painting patch; a global optimization of the warp is used to minimize distortion in the painting strokes. This approach outperforms prior algorithms in problem areas of the image, where flickering typically occurs, while producing comparable results elsewhere. In particular, stable strokes are produced at occlusion boundaries where objects emerge, and at image borders exposed by camera panning. A further advantage is consistent rendering of regions before and after brief occlusion, enhancing temporal stability of the output of discontiguous frames.

关键词： non-photorealistic rendering painterly rendering stroke placement region clustering video ren- dering flicker

Comfort-driven disparity adjustment for stereoscopic video

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Computational Visual Media 2016年第1期2卷 3-17页

作者： Miao Wang Xi-Jin Zhang Jun-Bang Liang Song-Hai Zhang ralph R.martin Department of Computer Science and Technology Tsinghua University Cardiff University

Pixel disparity—the offset of corresponding pixels between left and right views—is a crucial parameter in stereoscopic three-dimensional(S3D)video, as it determines the depth perceived by the human visual system(HVS). Unsuitable pixel disparity distribution throughout an S3 D video may lead to visual discomfort. We present a unified and extensible stereoscopic video disparity adjustment framework which improves the viewing experience for an S3 D video by keeping the perceived 3D appearance as unchanged as possible while minimizing discomfort. We first analyse disparity and motion attributes of S3 D video in general, then derive a wide-ranging visual discomfort metric from existing perceptual comfort models. An objective function based on this metric is used as the basis of a hierarchical optimisation method to find a disparity mapping function for each input video frame. Warping-based disparity manipulation is then applied to the input video to generate the output video, using the desired disparity mappings as constraints. Our comfort metric takes into account disparity range, motion, and stereoscopic window violation; the framework could easily be extended to use further visual comfort models. We demonstrate the power of our approach using both animated cartoons and real S3 D videos.

关键词： stereoscopic video editing video enhancement perceptual visual computing video manipulation

Video Structure Analysis

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2007年第6期12卷 714-718页

作者：张松海张一飞陈韬 Peter M. Hall ralph martin Department of Computer Science and Technology Tsinghua University Department of Computer Science University of Bath Bath BA2 7AY United Kingdom School of Computer Science Cardiff University Wales CF24 3AA United Kingdom

Video structure analysis is a basic requirement for most content-based video editing and processing systems. This paper presents a fast video structure analysis method based on image segmentation in each frame, with region matching between frames. The structure analysis decomposes the video into several moving objects, including information about their colors, positions, shapes, movements, and lifetimes. The method also supports user interactions to improve the results. The result shows that this method is fast and stable and can complete video analyzinq interactivelv.

关键词： video structure analysis video segmentation image segmentation region matching

Attention mechanisms in computer vision:A survey

在线全文

学校读者我要写书评

暂无评论

Computational Visual Media 2022年第3期8卷 331-368页

作者： Meng-Hao Guo Tian-Xing Xu Jiang-Jiang Liu Zheng-Ning Liu Peng-Tao Jiang Tai-Jiang Mu Song-Hai Zhang ralph R.martin Ming-Ming Cheng Shi-Min Hu BNRist Department of Computer Science and TechnologyTsinghua UniversityBeijing 100084China TKLNDST College of Computer ScienceNankai UniversityTianjin 300350China School of Computer Science and Informatics Cardiff UniversityCardiffUK

Humans can naturally and effectively find salient regions in complex *** by this observation,attention mechanisms were introduced into computer vision with the aim of imitating this aspect of the human visual *** an attention mechanism can be regarded as a dynamic weight adjustment process based on features of the input *** mechanisms have achieved great success in many visual tasks,including image classification,object detection,semantic segmentation,video understanding,image generation,3D vision,multimodal tasks,and self-supervised *** this survey,we provide a comprehensive review of various attention mechanisms in computer vision and categorize them according to approach,such as channel attention,spatial attention,temporal attention,and branch attention;a related repository https://***/MenghaoG uo/Awesome-Vision-Attentions is dedicated to collecting related *** also suggest future directions for attention mechanism research.

关键词： attention transformer computer vision deep learning salience