Yigang Wang - Academia.edu (original) (raw)

Papers by Yigang Wang

Optical Engineering, Aug 1, 1998

ABSTRACT

Journal of Computer-Aided Design & Computer Graphics

Massive open online courses (MOOC) are free online courses that provide educational resources to ... more Massive open online courses (MOOC) are free online courses that provide educational resources to users. In this paper, related works are summarized from the following perspectives: data types of MOOC, MOOC data visualization, and visual analysis applications of MOOC data. First, MOOC data is categorized into four types, including text data, video data, topological data, spatio-temporal data, and their concepts and applications are introduced. Then, the common visualization methods of different data types are discussed. Furthermore, the major applications of visual analytics approaches in MOOC data analysis are summarized, including online course learning, online tests and exams, online forum interaction and so on. Finally, the challenges and future work on visual analytics of MOOC data are discussed and concluded.

Applied Sciences

Free-viewpoint rendering has always been one of the key motivations of image-based rendering and ... more Free-viewpoint rendering has always been one of the key motivations of image-based rendering and has broad application prospects in the field of virtual reality and augmented reality (VR/AR). The existing methods mainly adopt the traditional image-based rendering or learning-based frameworks, which have limited viewpoint freedom and poor time performance. In this paper, the cube surface light field is utilized to encode the scenes implicitly, and an interactive free-viewpoint rendering method is proposed to solve the above two problems simultaneously. The core of this method is a pure light ray-based representation using the cube surface light field. Using a fast single-layer ray casting algorithm to compute the light ray’s parameters, the rendering is achieved by a GPU-based three-dimensional (3D) compressed texture mapping that converts the corresponding light rays to the desired image. Experimental results show that the proposed method can real-time render the novel views at arbi...

IEEE Access, 2020

This paper presents a simultaneous autoregressive (SAR) analysis method to describe the unknown s... more This paper presents a simultaneous autoregressive (SAR) analysis method to describe the unknown signal-to-noise ratio (SNR) and the texture feature of low-quality real video frames when the ground-truth images are not available. The real video images degraded by the factors, such as electronic noise, oversaturated pixels, motion blur, and compression artifacts, often result in poor motion registration estimation, which makes the performance of the existing video super-resolution (VSR) algorithms lower than expected. It is hard to estimate the SNR of the low-quality real frames without any prior knowledge. To solve this problem, we made a connection between SAR hyperparameters and the SNR of real images. The relationship expression of them was given in this paper. Using the proposed method, well-registered low-quality real video frames can be selected to decrease the root mean squared error (RMSE) of motion estimation of video frames for VSR reconstruction improvement. The anomalous low-quality frame images whose SAR hyperparameters values are inconsistent with others will be considered for removal. Synthetic experiments were designed to illustrate how the SAR hyperparameters values vary with the variation of synthetic parameters. In order to better illustrate the effectiveness of the proposed method, real low-quality videos captured under different conditions were tested under VSR reconstruction experiments. The VSR reconstruction results show that the results obtained using SAR prior analysis have sharper edges and fewer ringing artifacts than the original results. It indicates that the proposed method is helpful to obtain better results of motion registration estimation for low-quality real video images.

Applied Mathematics-A Journal of Chinese Universities, 2020

This paper presents an interpolation-based method (IBM) for approximating some trigonometric func... more This paper presents an interpolation-based method (IBM) for approximating some trigonometric functions or their integrals as well. It provides two-sided bounds for each function, which also achieves much better approximation effects than those of prevailing methods. In principle, the IBM can be applied for bounding more bounded smooth functions and their integrals as well, and its applications include approximating the integral of sin(x)/x function and improving the famous square root inequalities.

Journal of Physics: Conference Series, 2019

With the development and wide application of virtual reality technology, the emerging virtual rea... more With the development and wide application of virtual reality technology, the emerging virtual reality system brings better visual experience. In the field of scientific visualization, immersive visual experience and well-designed interactive method can enhance user experience. Since traditional 2D input devices such as mouse and keyboard cannot support direct 3D manipulation, they cannot be applied to virtual reality visualization. Moreover, basic VR interactive devices like controllers also have some problems such as low operation precision and the lack of sensory simulation and real-time feedback operation. In order to solve these problems, we propose a virtual reality interactive method based on force feedback to deal with the complex interactive operation of scientific data in 3D space. We also reported a user testing which compared our approach with traditional VR controllers in same tasks demonstrates that the proposed approach has higher accuracy and better user experience.

Journal of Inequalities and Applications, 2018

Inequalities are frequently used for solving practical engineering problem. There are two key iss... more Inequalities are frequently used for solving practical engineering problem. There are two key issues of bounding inequalities; one is to find the bounds, and the other is to prove the bounds. This paper takes Wilker type inequalities as an example, presents a two-point-Padé-approximant-based method for finding the bounds, and it also provides a method to prove the bounds in a new way. It not only recovers the estimates in Mortici's method, but it also provides new improvements of estimates obtained from prevailing methods. In principle, it can be applied for other inequalities.

IEEE Computer Graphics and Applications, 2019

We present a novel active learning approach for shape cosegmentation based on graph convolutional... more We present a novel active learning approach for shape cosegmentation based on graph convolutional networks (GCNs). The premise of our approach is to represent the collections of three-dimensional shapes as graph-structured data, where each node in the graph corresponds to a primitive patch of an oversegmented shape, and is associated with a representation initialized by extracting features. Then, the GCN operates directly on the graph to update the representation of each node based on a layer-wise propagation rule, which aggregates information from its neighbors, and predicts the labels for unlabeled nodes. Additionally, we further suggest an active learning strategy that queries the most informative samples to extend the initial training samples of GCN to generate more accurate predictions of our method. Our experimental results on the Shape COSEG dataset demonstrate the effectiveness of our approach. & SEGMENTATION OF THREE-DIMENSIONAL (3-D) shapes is a fundamental operation in geometric modeling and shape analysis. Recently, researchers have observed that by segmenting a set of 3-D shapes as a whole into consistent parts one can infer more knowledge than from an individual shape. This is the problem of cosegmentation. The results of shape cosegmentation can be applied to various applications in computer graphics and vision, such as modeling, shape retrieval, texturing, etc.

Journal of Computer Science and Technology, 2015

Previous collision detection methods for virtual disassembly mainly detect collisions at discrete... more Previous collision detection methods for virtual disassembly mainly detect collisions at discrete time intervals, and use oriented bounding boxes to speed up the process. However, these discrete methods cannot guarantee no penetration occurs when the components move. Meanwhile, because some of the components are embedded into each other, these components cannot be separated in the subsequent process. To solve these problems, we propose an approach for real-time collision handling by utilizing the computational power of modern GPUs. First we present a novel GPU-based collision handling framework for virtual disassembly. Second we use a collision-streams based continuous collision detection to guarantee no collision missed. Finally we introduce a triangle intersection detection algorithm to solve the problem that collision cannot be detected when the components are embedded into each other at the initial configuration. The experimental results show that our method can improve the overall performance of collision detection and achieve real-time simulation.

Computer Graphics Forum, 2014

To design a bas-relief from a 3D scene is an inherently interactive task in many scenarios. The u... more To design a bas-relief from a 3D scene is an inherently interactive task in many scenarios. The user normally needs to get instant feedback to select a proper viewpoint. However, current methods are too slow to facilitate this interaction. This paper proposes a two-scale bas-relief modeling method, which is computationally efficient and easy to produce different styles of bas-reliefs. The input 3D scene is first rendered into two textures, one recording the depth information and the other recording the normal information. The depth map is then compressed to produce a base surface with level-of-depth, and the normal map is used to extract local details with two different schemes. One scheme provides certain freedom to design bas-reliefs with different visual appearances, and the other provides a control over the level of detail. Finally, the local feature details are added into the base surface to produce the final result. Our approach allows for real-time computation due to its implementation on graphics hardware. Experiments with a wide range of 3D models and scenes show that our approach can effectively generate digital bas-reliefs in real time.

Scientia Sinica Informationis, 2014

提出了一种基于 splatting 的深度图生成与可见性判定方法 (4.2 小节), 区分可见与不可见表 面的特征线. 通过自适应的深度偏移提高可见性判定的准确率. (3) 实现高效的数据剔除与... more 提出了一种基于 splatting 的深度图生成与可见性判定方法 (4.2 小节), 区分可见与不可见表 面的特征线. 通过自适应的深度偏移提高可见性判定的准确率. (3) 实现高效的数据剔除与压缩算法 (4.3 小节), 在不损失绘制精度的前提下将数据量减少为原有 数据的 10% 至 30%, 显著地减少了数据传输的带宽, 提高了绘制效率.

Lecture Notes in Computer Science, 2006

This paper investigates facial expression effects in face recognition from 3D shape using partial... more This paper investigates facial expression effects in face recognition from 3D shape using partial ICP. The partial ICP method could implicitly and dynamically extract the rigid parts of facial surface by selecting a part of nearest points pairs to calculate dissimilarity measure during registration of facial surfaces. The method is expected to be able to get much better performance than other methods in 3D face recognition under expression variation for its dynamic extraction of rigid parts of facial surface at the same time of matching. We also present an effective method for coarse alignment of facial shape, which is fully automatic. Experiments on 3D face database of 360 models with 40 subjects, 9 scans with four different kinds of expression for each subject, show partial ICP is very promising, compared with PCA baseline.

16th International Conference on Artificial Reality and Telexistence--Workshops (ICAT'06), 2006

A large display system usually consists of many projectors, whose projections are merged together... more A large display system usually consists of many projectors, whose projections are merged together to form a large screen. In this paper, we discuss technologies to join multiple projections into a large display system for multimedia entertainment and virtual reality applications. In contrast to using expensive hardware-based seamlessly merging modules, we adopt a software-based seamlessly merging solution, which is used to calibrate the color brightness and the geometry in superposed regions. And in order to enlarging its application, we adapt technology to several kinds of screens (plane screen and camber screen). We use PC cluster with accelerated graphics cards to lower rendering costs. Our software merge system can run on a variety of large display platforms. The experiment shows our system obtain the satisfying results. It can seamlessly play videos with different encoding formats, such as avi, wmv, rm etc, and can seamlessly render 3D scenes in real time.

Journal of Computational and Applied Mathematics, 2009

Computers & Graphics, 2003

This paper presents a general method for selectively refining or coarsening progressive meshes. O... more This paper presents a general method for selectively refining or coarsening progressive meshes. Our method works for arbitrary meshes, deals with non-manifolds, and allows the change of manifold and genus properties of the mesh. We introduce new definitions for edge contraction and expansion operations, which make solely use of the vertex hierarchy. These definitions in conjunction with their legal conditions lead to many provable properties of the refinement process. In addition, we propose a locally re-stripping method to dynamically generate the strips during selective refinements, which efficiently forms strips for meshes coarsening or refining process.

Computer Graphics Forum, 2010

This paper presents a novel modeling system, called B‐Mesh, for generating base meshes of 3D arti... more This paper presents a novel modeling system, called B‐Mesh, for generating base meshes of 3D articulated shapes. The user only needs to draw a one‐dimensional skeleton and to specify key balls at the skeletal nodes. The system then automatically generates a quad dominant initial mesh. Further subdivision and evolution are performed to refine the initial mesh and generate a quad mesh which has good edge flow along the skeleton directions. The user can also modify and manipulate the shape by editing the skeleton and the key balls and can easily compose new shapes by cutting and pasting existing models in our system. The mesh models generated in our system greatly benefit the sculpting operators for sculpting modeling and skeleton‐based animation.

Next Generation Computer Animation Techniques, 2017

In the field of scientific visualization, 3D manipulation is a fundamental task for many differen... more In the field of scientific visualization, 3D manipulation is a fundamental task for many different scientific datasets, such as particle data in physics and astronomy, fluid data in aerography, and structured data in medical science. Current researches show that large multi-touch interactive displays serve as a promising device providing numerous significant advantages for displaying and manipulating scientific data. Those benefits of direct-touch devices motivate us to use touch-based interaction techniques to explore scientific 3D data. However, manipulating object in 3D space via 2D touch input devices is challenging for precise control. Therefore, we present a novel multi-touch approach for manipulating structured objects in 3D visualization space, based on multi-touch gestures and an extra axis for the assistance. Our method supports 7-DOF manipulations. Moreover, with the help from the extra axis and depth hints, users can have better control of the interactions. We report on a user study to make comparisons between our method and standard mouse-based 2D interface. We show in this work that touch-based interactive displays can be more effective when applied to complex problems if the interactive visualizations and interactions are designed appropriately.

International Symposium on Multispectral Image Processing (ISMIP'98), 1998

ABSTRACT

Computer Graphics Forum, 1998

This paper proposes a new preprocessing method for interactive rendering of complex polygonal vir... more This paper proposes a new preprocessing method for interactive rendering of complex polygonal virtual environments. The approach divides the space that observer can reach into many rectangular viewpoint regions. For each region, an outer rectangular volume(ORV) is established to surround it. By adaptively partitioning the boundary of the ORV together with the viewpoint region, all the rays that originate from the viewpoint region are divided into the beams whose potentially visible polygon number is less than a preset threshold. If a resultant beam is the smallest and intersects many potentially visible polygons, the beam is simplified as a fixed number of rays and the averaged color of the hit polygons is recorded. For other beams, their potentially visible sets (PVS) of polygons are stored respectively. During an interactive walkthrough, the visual information related to the current viewpoint is retrieved from the storage. The view volume clipping, visibility culling and detail simplification are efficiently supported by these stored data. The rendering time is independent of the scene complexity.

Optical Engineering, Aug 1, 1998

ABSTRACT

Journal of Computer-Aided Design & Computer Graphics

Massive open online courses (MOOC) are free online courses that provide educational resources to ... more Massive open online courses (MOOC) are free online courses that provide educational resources to users. In this paper, related works are summarized from the following perspectives: data types of MOOC, MOOC data visualization, and visual analysis applications of MOOC data. First, MOOC data is categorized into four types, including text data, video data, topological data, spatio-temporal data, and their concepts and applications are introduced. Then, the common visualization methods of different data types are discussed. Furthermore, the major applications of visual analytics approaches in MOOC data analysis are summarized, including online course learning, online tests and exams, online forum interaction and so on. Finally, the challenges and future work on visual analytics of MOOC data are discussed and concluded.

Applied Sciences

Free-viewpoint rendering has always been one of the key motivations of image-based rendering and ... more Free-viewpoint rendering has always been one of the key motivations of image-based rendering and has broad application prospects in the field of virtual reality and augmented reality (VR/AR). The existing methods mainly adopt the traditional image-based rendering or learning-based frameworks, which have limited viewpoint freedom and poor time performance. In this paper, the cube surface light field is utilized to encode the scenes implicitly, and an interactive free-viewpoint rendering method is proposed to solve the above two problems simultaneously. The core of this method is a pure light ray-based representation using the cube surface light field. Using a fast single-layer ray casting algorithm to compute the light ray’s parameters, the rendering is achieved by a GPU-based three-dimensional (3D) compressed texture mapping that converts the corresponding light rays to the desired image. Experimental results show that the proposed method can real-time render the novel views at arbi...

IEEE Access, 2020

This paper presents a simultaneous autoregressive (SAR) analysis method to describe the unknown s... more This paper presents a simultaneous autoregressive (SAR) analysis method to describe the unknown signal-to-noise ratio (SNR) and the texture feature of low-quality real video frames when the ground-truth images are not available. The real video images degraded by the factors, such as electronic noise, oversaturated pixels, motion blur, and compression artifacts, often result in poor motion registration estimation, which makes the performance of the existing video super-resolution (VSR) algorithms lower than expected. It is hard to estimate the SNR of the low-quality real frames without any prior knowledge. To solve this problem, we made a connection between SAR hyperparameters and the SNR of real images. The relationship expression of them was given in this paper. Using the proposed method, well-registered low-quality real video frames can be selected to decrease the root mean squared error (RMSE) of motion estimation of video frames for VSR reconstruction improvement. The anomalous low-quality frame images whose SAR hyperparameters values are inconsistent with others will be considered for removal. Synthetic experiments were designed to illustrate how the SAR hyperparameters values vary with the variation of synthetic parameters. In order to better illustrate the effectiveness of the proposed method, real low-quality videos captured under different conditions were tested under VSR reconstruction experiments. The VSR reconstruction results show that the results obtained using SAR prior analysis have sharper edges and fewer ringing artifacts than the original results. It indicates that the proposed method is helpful to obtain better results of motion registration estimation for low-quality real video images.

Applied Mathematics-A Journal of Chinese Universities, 2020

This paper presents an interpolation-based method (IBM) for approximating some trigonometric func... more This paper presents an interpolation-based method (IBM) for approximating some trigonometric functions or their integrals as well. It provides two-sided bounds for each function, which also achieves much better approximation effects than those of prevailing methods. In principle, the IBM can be applied for bounding more bounded smooth functions and their integrals as well, and its applications include approximating the integral of sin(x)/x function and improving the famous square root inequalities.

Journal of Physics: Conference Series, 2019

With the development and wide application of virtual reality technology, the emerging virtual rea... more With the development and wide application of virtual reality technology, the emerging virtual reality system brings better visual experience. In the field of scientific visualization, immersive visual experience and well-designed interactive method can enhance user experience. Since traditional 2D input devices such as mouse and keyboard cannot support direct 3D manipulation, they cannot be applied to virtual reality visualization. Moreover, basic VR interactive devices like controllers also have some problems such as low operation precision and the lack of sensory simulation and real-time feedback operation. In order to solve these problems, we propose a virtual reality interactive method based on force feedback to deal with the complex interactive operation of scientific data in 3D space. We also reported a user testing which compared our approach with traditional VR controllers in same tasks demonstrates that the proposed approach has higher accuracy and better user experience.

Journal of Inequalities and Applications, 2018

Inequalities are frequently used for solving practical engineering problem. There are two key iss... more Inequalities are frequently used for solving practical engineering problem. There are two key issues of bounding inequalities; one is to find the bounds, and the other is to prove the bounds. This paper takes Wilker type inequalities as an example, presents a two-point-Padé-approximant-based method for finding the bounds, and it also provides a method to prove the bounds in a new way. It not only recovers the estimates in Mortici's method, but it also provides new improvements of estimates obtained from prevailing methods. In principle, it can be applied for other inequalities.

IEEE Computer Graphics and Applications, 2019

We present a novel active learning approach for shape cosegmentation based on graph convolutional... more We present a novel active learning approach for shape cosegmentation based on graph convolutional networks (GCNs). The premise of our approach is to represent the collections of three-dimensional shapes as graph-structured data, where each node in the graph corresponds to a primitive patch of an oversegmented shape, and is associated with a representation initialized by extracting features. Then, the GCN operates directly on the graph to update the representation of each node based on a layer-wise propagation rule, which aggregates information from its neighbors, and predicts the labels for unlabeled nodes. Additionally, we further suggest an active learning strategy that queries the most informative samples to extend the initial training samples of GCN to generate more accurate predictions of our method. Our experimental results on the Shape COSEG dataset demonstrate the effectiveness of our approach. & SEGMENTATION OF THREE-DIMENSIONAL (3-D) shapes is a fundamental operation in geometric modeling and shape analysis. Recently, researchers have observed that by segmenting a set of 3-D shapes as a whole into consistent parts one can infer more knowledge than from an individual shape. This is the problem of cosegmentation. The results of shape cosegmentation can be applied to various applications in computer graphics and vision, such as modeling, shape retrieval, texturing, etc.

Journal of Computer Science and Technology, 2015

Previous collision detection methods for virtual disassembly mainly detect collisions at discrete... more Previous collision detection methods for virtual disassembly mainly detect collisions at discrete time intervals, and use oriented bounding boxes to speed up the process. However, these discrete methods cannot guarantee no penetration occurs when the components move. Meanwhile, because some of the components are embedded into each other, these components cannot be separated in the subsequent process. To solve these problems, we propose an approach for real-time collision handling by utilizing the computational power of modern GPUs. First we present a novel GPU-based collision handling framework for virtual disassembly. Second we use a collision-streams based continuous collision detection to guarantee no collision missed. Finally we introduce a triangle intersection detection algorithm to solve the problem that collision cannot be detected when the components are embedded into each other at the initial configuration. The experimental results show that our method can improve the overall performance of collision detection and achieve real-time simulation.

Computer Graphics Forum, 2014

To design a bas-relief from a 3D scene is an inherently interactive task in many scenarios. The u... more To design a bas-relief from a 3D scene is an inherently interactive task in many scenarios. The user normally needs to get instant feedback to select a proper viewpoint. However, current methods are too slow to facilitate this interaction. This paper proposes a two-scale bas-relief modeling method, which is computationally efficient and easy to produce different styles of bas-reliefs. The input 3D scene is first rendered into two textures, one recording the depth information and the other recording the normal information. The depth map is then compressed to produce a base surface with level-of-depth, and the normal map is used to extract local details with two different schemes. One scheme provides certain freedom to design bas-reliefs with different visual appearances, and the other provides a control over the level of detail. Finally, the local feature details are added into the base surface to produce the final result. Our approach allows for real-time computation due to its implementation on graphics hardware. Experiments with a wide range of 3D models and scenes show that our approach can effectively generate digital bas-reliefs in real time.

Scientia Sinica Informationis, 2014

提出了一种基于 splatting 的深度图生成与可见性判定方法 (4.2 小节), 区分可见与不可见表 面的特征线. 通过自适应的深度偏移提高可见性判定的准确率. (3) 实现高效的数据剔除与... more 提出了一种基于 splatting 的深度图生成与可见性判定方法 (4.2 小节), 区分可见与不可见表 面的特征线. 通过自适应的深度偏移提高可见性判定的准确率. (3) 实现高效的数据剔除与压缩算法 (4.3 小节), 在不损失绘制精度的前提下将数据量减少为原有 数据的 10% 至 30%, 显著地减少了数据传输的带宽, 提高了绘制效率.

Lecture Notes in Computer Science, 2006

This paper investigates facial expression effects in face recognition from 3D shape using partial... more This paper investigates facial expression effects in face recognition from 3D shape using partial ICP. The partial ICP method could implicitly and dynamically extract the rigid parts of facial surface by selecting a part of nearest points pairs to calculate dissimilarity measure during registration of facial surfaces. The method is expected to be able to get much better performance than other methods in 3D face recognition under expression variation for its dynamic extraction of rigid parts of facial surface at the same time of matching. We also present an effective method for coarse alignment of facial shape, which is fully automatic. Experiments on 3D face database of 360 models with 40 subjects, 9 scans with four different kinds of expression for each subject, show partial ICP is very promising, compared with PCA baseline.

16th International Conference on Artificial Reality and Telexistence--Workshops (ICAT'06), 2006

A large display system usually consists of many projectors, whose projections are merged together... more A large display system usually consists of many projectors, whose projections are merged together to form a large screen. In this paper, we discuss technologies to join multiple projections into a large display system for multimedia entertainment and virtual reality applications. In contrast to using expensive hardware-based seamlessly merging modules, we adopt a software-based seamlessly merging solution, which is used to calibrate the color brightness and the geometry in superposed regions. And in order to enlarging its application, we adapt technology to several kinds of screens (plane screen and camber screen). We use PC cluster with accelerated graphics cards to lower rendering costs. Our software merge system can run on a variety of large display platforms. The experiment shows our system obtain the satisfying results. It can seamlessly play videos with different encoding formats, such as avi, wmv, rm etc, and can seamlessly render 3D scenes in real time.

Journal of Computational and Applied Mathematics, 2009

Computers & Graphics, 2003

This paper presents a general method for selectively refining or coarsening progressive meshes. O... more This paper presents a general method for selectively refining or coarsening progressive meshes. Our method works for arbitrary meshes, deals with non-manifolds, and allows the change of manifold and genus properties of the mesh. We introduce new definitions for edge contraction and expansion operations, which make solely use of the vertex hierarchy. These definitions in conjunction with their legal conditions lead to many provable properties of the refinement process. In addition, we propose a locally re-stripping method to dynamically generate the strips during selective refinements, which efficiently forms strips for meshes coarsening or refining process.

Computer Graphics Forum, 2010

This paper presents a novel modeling system, called B‐Mesh, for generating base meshes of 3D arti... more This paper presents a novel modeling system, called B‐Mesh, for generating base meshes of 3D articulated shapes. The user only needs to draw a one‐dimensional skeleton and to specify key balls at the skeletal nodes. The system then automatically generates a quad dominant initial mesh. Further subdivision and evolution are performed to refine the initial mesh and generate a quad mesh which has good edge flow along the skeleton directions. The user can also modify and manipulate the shape by editing the skeleton and the key balls and can easily compose new shapes by cutting and pasting existing models in our system. The mesh models generated in our system greatly benefit the sculpting operators for sculpting modeling and skeleton‐based animation.

Next Generation Computer Animation Techniques, 2017

In the field of scientific visualization, 3D manipulation is a fundamental task for many differen... more In the field of scientific visualization, 3D manipulation is a fundamental task for many different scientific datasets, such as particle data in physics and astronomy, fluid data in aerography, and structured data in medical science. Current researches show that large multi-touch interactive displays serve as a promising device providing numerous significant advantages for displaying and manipulating scientific data. Those benefits of direct-touch devices motivate us to use touch-based interaction techniques to explore scientific 3D data. However, manipulating object in 3D space via 2D touch input devices is challenging for precise control. Therefore, we present a novel multi-touch approach for manipulating structured objects in 3D visualization space, based on multi-touch gestures and an extra axis for the assistance. Our method supports 7-DOF manipulations. Moreover, with the help from the extra axis and depth hints, users can have better control of the interactions. We report on a user study to make comparisons between our method and standard mouse-based 2D interface. We show in this work that touch-based interactive displays can be more effective when applied to complex problems if the interactive visualizations and interactions are designed appropriately.

International Symposium on Multispectral Image Processing (ISMIP'98), 1998

ABSTRACT

Computer Graphics Forum, 1998

This paper proposes a new preprocessing method for interactive rendering of complex polygonal vir... more This paper proposes a new preprocessing method for interactive rendering of complex polygonal virtual environments. The approach divides the space that observer can reach into many rectangular viewpoint regions. For each region, an outer rectangular volume(ORV) is established to surround it. By adaptively partitioning the boundary of the ORV together with the viewpoint region, all the rays that originate from the viewpoint region are divided into the beams whose potentially visible polygon number is less than a preset threshold. If a resultant beam is the smallest and intersects many potentially visible polygons, the beam is simplified as a fixed number of rays and the averaged color of the hit polygons is recorded. For other beams, their potentially visible sets (PVS) of polygons are stored respectively. During an interactive walkthrough, the visual information related to the current viewpoint is retrieved from the storage. The view volume clipping, visibility culling and detail simplification are efficiently supported by these stored data. The rendering time is independent of the scene complexity.