Writing and editing mathematical expressions with complicated structures in computer system is difficult and time-consuming. To address this, we proposed MathAssist, a mathematical expression autocomplete technique that recommends full formulas in real-time based on the user’s input strokes. Our technique identifies user’s input purpose by matching the structure of the current user input to the structure of formulas in a database. To facilitate such process, we propose a novel tree-based formalization to represent formula. In comparison to a mathematical expression recognition algorithm (SRD) and a commercial MicroSoft Ink Equation (InkEqu), our approach outperformed both of them on task completion time (reduced by 37.14% and 37.58%) and accuracy (32.78% and 10.55% higher). We also discuss our findings in using autocomplete to assist formula editing.

With the development of virtual reality (VR) and human-computer interaction technology, how to use natural and efficient interaction methods in the virtual environment has become a hot topic of research. Gesture is one of the most important communication methods of human beings, which can effectively express users’ demands. In the past few decades, gesture-based interaction has made significant progress. This article focuses on the gesture interaction technology and discusses the definition and classification of gestures, input devices for gesture interaction, and gesture interaction recognition technology. The application of gesture interaction technology in virtual reality is studied, the existing problems in the current gesture interaction are summarized, and the future development is prospected.

Background Owing to recent advances in virtual reality (VR) technologies, effective user interaction with dynamic content in 3D scenes has become a research hotspot. Moving target selection is a basic interactive task in which the user performance research in tasks is significant to user interface design in VR. Different from the existing static target selection studies, the moving target selection in VR is affected by the change in target speed, angle and size, and lack of research on some key factors. Methods This study designs an experimental scenario in which the users play badminton under the condition of VR. By adding seven kinds of modal clues such as vision, audio, haptics, and their combinations, five kinds of moving speed and four kinds of serving angles, and the effect of these factors on the performance and subjective feelings in moving target selection in VR, is studied. Results The results show that the moving speed of the shuttlecock has a significant impact on the user performance. The angle of service has a significant impact on hitting rate, but has no significant impact on the hitting distance. The acquisition of the user performance by the moving target is mainly influenced by vision under the combined modalities; adding additional modalities can improve user performance. Although the hitting distance of the target is increased in the trimodal condition, the hitting rate decreases. Conclusion This study analyses the results of user performance and subjective perception, and then provides suggestions on the combination of modality clues in different scenarios.

Background Crossing-based target selection motion may attain less error rates and higher interactive speed in some cases. Most of the research in target selection fields are focused on the analysis of the interaction results. Additionally, as trajectories play a much more important role in crossing-based target selection compared to the other interactive techniques, an ideal model for trajectories can help computer designers make predictions about interaction results during the process of target selection rather than at the end of the whole process. Methods In this paper, a trajectory prediction model for crossing-based target selection tasks is proposed by taking the reference of a dynamic model theory. Results Simulation results demonstrate that our model performed well with regard to the prediction of trajectories, endpoints and hitting time for target-selection motion, and the average error of trajectories, endpoints and hitting time values were found to be 17.28%, 2.73mm and 11.50%, respectively.

While instrumental ensemble playing can benefit children's music education and collaboration skill development, it requires extensive training on music and instruments, which many school children lack. To help children with limited music training experience instrumental ensemble playing, we created EnseWing, an interactive system that offers such an experience. In this paper, we report the design of the EnseWing experience and a two-month field study. Our results show that EnseWing preserves the music and ensemble skills from traditional instrumental ensemble and provides more collaboration opportunities for children.

A majority of video summarization systems use linear representations, such as rectangular storyboards and timelines at linear scales. In this paper, we propose a novel nonlinear dynamic representation called SpiralTape that summarizes a video in a smooth spiral pattern. SpiralTape provides an unusual and fresh activity suitable for stimulating environments such as science and technology museums, in which children or young individuals can have enjoyable experiences that create meaningful learning outcomes. In addition, SpiralTape provides an uninterrupted overall structure of video content and takes design principles including compactness, continuity, efficient overview, and interactivity into consideration. A working SpiralTape system was developed and deployed in pilot applications and exhibitions. Elaborate user studies with evaluation benchmarks on multiple metrics were conducted to compare SpiralTape with two representative linear video summarization methods and a state-of-the-art radial video visualization. The evaluation results demonstrate the effectiveness and natural interaction performance of SpiralTape.

In multi-touch interactive systems, it is of great significance to distinguish which hand of the user is touching the surface in real time. Left-right hand distinction is essential for recognizing the multi-finger gestures and further fully exploring the potential of bimanual interaction. However, left-right hand distinction is beyond the capability of most existing multi-touch systems. In this paper, we present a new method for left and right hand distinction based on the human anatomy, work area, finger orientation and finger position. Considering the ergonomics principles of gesture designing, the body-forearm triangle model was proposed. Furthermore, a heuristic algorithm was introduced to group multi-touch contact points and then made left-right hand distinction. A dataset of 2880 images has been set up to evaluate the proposed left-right hand distinction method. The experimental results demonstrate that our method can guarantee the high recognition accuracy and real time performance in freely bimanual multi-touch interactions.

In China, hundreds of millions of migrant workers have moved to cities or coastal regions for more or better-paid jobs and have left their children behind at their rural homes. Separated by thousands of kilometers, these "left-behind" children and their migrant parents use mobile phones as their primary - and often only - method of maintaining family connections. To better understand the use of technology in this long-distance communication, we conducted a multi-phased study using interviews and surveys in three different Chinese rural areas. In this paper, we report our findings on how these children communicate with their migrant parents and what information they exchange. We also discuss design implications derived from these findings that may improve communication between left-behind children and their parents.

Infovis (Information visualization) task taxonomy plays an essential role in guiding Infovis design and implementation. Infovis users with various roles in Infovis usually have different requirements for Infovis task modeling. Actually, Infovis research need a consistent taxonomy covering the tasks at different levels, or an interaction model that can facilitate Infovis system development with formal descriptions. But in fact, finding such a unified model is challenging. In this paper we propose a multilevel interaction model (MIM) for hierarchical tasks in Infovis systems. In MIM we define goal model, behavior model, and operation model that can model multilevel tasks in Infovis. In addition, we establish mapping models among MIM components, which can support Infovis systems design, development, application, and evaluation. Finally, we present a domain-specific Infovis application modeled by MIM. Application examples shows that MIM can effectively model multilevel tasks in Infovis and has potential to provide a framework enabling rapid prototyping of Infovis systems.

Gesture inputs on multi-touch tabletops usually involve multiple fingers (more than two) and casual touchdowns or liftoffs of fingers. This flexibility of touch gestures allows more natural user interaction, but also poses new challenges for accurate recognition of multi-touch gestures. To address these challenges, we propose a new approach to recognize flexible multi-touch stroke gestures on tabletops. Based on a user study on multi-touch unistroke gestures, we develop a gesture recognition method by extracting key strokes embedded in flexible multi-touch input. Our evaluation study result shows that this method can greatly improve the recognition accuracy of flexible multi-touch unistroke gestures on tabletops.

Authoring context-aware, interactive video representation is usually a complex process. A user-friendly multimedia authoring environment is thus solicited to explore and express users' design ideas efficiently and naturally. In this paper we present a sketch-based two-layer representation, called scene structure graph (SSG), to facilitate the video authoring process. One layer in SSG uses sketches as a concise form with which the visualization of scene information is easily understood and the other layer uses a graph to represent and edit the narrative structure in the authoring process. With SSG, the authoring process works in two stages. In the first stage, various sketch forms such as symbols and hand-drawing illustrations are used as basic primitives to annotate the video clips and the hyperlinks encoding spatio-temporal relations are established in SSG. In the second stage, sketches in SSGs are modified and new SSG is composed for any particular authoring purpose. Three user studies are elaborated, showing that the SSG is user-friendly and can achieve a good balance between expressiveness of users' intent and ease of use for authoring of interactive video.

The classical Mean Shift can't change the scale of tracking window in real time while tracking target is changing in size. This paper adopts graph cuts theory to the problem of scale adaptation for Mean Shift tracking. According to the result of Mean Shift iteration in every frame, implementing graph cuts using skin color Gaussian mixture model(GMM) in a small area around it, and updating tracking window size through the largest skin lump among the result of graph cuts. Experimental results clearly demonstrate that the method can reflect the real scale change of tracking target, avoid the interference of other objects in background, and has good usability and robustness. Besides it enriches manipulation method of Human Computer Interaction by controlling entertainment games.

With the fast economic growth and urbanization of many developing countries come concerns that their children now have fewer opportunities to express creativity and develop collaboration skills, or to experience their local cultural heritage. We propose to address these concerns by creating technologies inspired by traditional arts, and allowing children to create and collaborate through playing with them. ShadowStory is our first attempt in this direction, a digital storytelling system inspired by traditional Chinese shadow puppetry. We present the design and implementation of ShadowStory and a 7-day field trial in a primary school. Findings illustrated that ShadowStory promoted creativity, collaboration, and intimacy with traditional culture among children, as well as interleaved children's digital and physical playing experience.

Recently, pen tilting has been explored in pen-based user interfaces and has shown potential to improve user interaction in various tasks (e.g., menu selection, modeless object manipulation). However, some basic questions concerning pen tilting behaviors, such as the ideal range, azimuth size, and direction of pen tilting, have not been thoroughly investigated. In this paper, we report our empirical studies on user performances in basic pen tilting tasks. First, we conducted a baseline study, which helps us to determine tilting directions, tilting ranges, and the thresholds that separate incidental pen tilting actions from intentional actions used for interaction. Based on the results from the baseline study, we designed an experiment to investigate user performances in goal tilting in different tilting ranges, azimuth sizes, and directions. Drawing on the results of our data analyses on task completion time, error rate, and pen tip movements, we discussed values of tilting parameters like titling range, minimal azimuth size, and tilting direction.

Along with the rapid development of information technology, individual users of computers are faced with many problems in dealing with massive files, such as enormous amount, serious redundancy and complex version evolution relation. These lead that the file system becomes more and more rough-and-tumble, to a certain extent putting users to trouble in daily work. This paper systematically analyzed the problems in file system management, put forward user cognitive model when faced with massive files, and then introduced the FDTVAS system which is a visual interface based on hyperbolic tree view for exploring the massive files. This system used specific algorithm to do the intelligent analysis of file relationship, took hyperbolic tree as the main visual form, and provided a series of interaction tasks according with users' cognitive model. The built system can help users get a clear insight of the file system and do the analysis and management efficiently.

In this paper, we present a new sketch-based system - KnitSketch, to improve the efficiency of process planning for knitting garments at an early design stage. The KnitSketch system utilizes sketching interface with the pen-paper metaphor and users only need to draw outlines of different parts of the garment. Based on sketching understanding, the system automatically makes reasonable geometric inferences about the process-planning data of the garment. The system is designed for nonprofessional users and can design diverse garment styles by freehand drawings. The contributions of this work include contextual extraction of reusable data from sketches, a MDG structure for sketch beautification, and an integrated system with natural expression and effective communication that reduces the cognitive load of human beings. User experience shows that the proposed system helps designers focus on the task instead of the designing tools, and thus improves the efficiency and productivity of human beings.

Concept maps are an important tool to organize, represent, and share knowledge. Building a concept map involves creating text-based concepts and specifying their relationships with line-based links. Current concept map tools usually impose specific task structures for text and link construction, and may increase cognitive burden to generate and interact with concept maps. While pen-based devices (e.g., tablet PCs) offer users more freedom in drawing concept maps with a pen or stylus more naturally, the support for hand-drawn concept map creation and manipulation is still limited, largely due to the lack of methods to recognize the components and structures of hand-drawn concept maps. This article proposes a method to understand hand-drawn concept maps. Our algorithm can extract node blocks, or concept blocks, and link blocks of a hand-drawn concept map by combining dynamic programming and graph partitioning, recognize the text content of each concept node, and build a concept-map structure by relating concepts and links. We also design an algorithm for concept map retrieval based on hand-drawn queries. With our algorithms, we introduce structure-based intelligent manipulation techniques and ink-based retrieval techniques to support the management and modification of hand-drawn concept maps. Results from our evaluation study show high structure recognition accuracy in real time of our method, and good usability of intelligent manipulation and retrieval techniques.

In many developing countries such as India and China, low educational levels often hinder economic empowerment. In this paper, we argue that mobile learning games can play an important role in the Chinese literacy acquisition process. We report on the unique challenges in the learning Chinese language, especially its logographic writing system. Based on an analysis of 25 traditional Chinese games currently played by children in China, we present the design and implementation of two culturally inspired mobile group learning games, Multimedia Word and Drumming Strokes. These two mobile games are designed to match Chinese children's understanding of everyday games. An informal evaluation reveals that these two games have the potential to enhance the intuitiveness and engagement of traditional games, and children may improve their knowledge of Chinese characters through group learning activities such as controversy, judgments and self-correction during the game play.

Research on complex shape recognition showed that the shape context algorithm is sensitive to relative position variation of articulation. Aimed at this problem, a shape recognition method is proposed based on local shape filling rate of various object silhouettes. We take each landmark point as a circle center and use as its radius. Then, under a particular radius, the ratio between the covered silhouette pixels and the total pixels is defined as local shape filling rate. Thus, different radius may form different local shape filling rates. All landmark points with different radius will constitute a characteristic matrix which can effectively reflects the entire statistical property of the object shape. Experiments on a variety of shape databases show that the novel method is insensitive to articulation and less influenced by the number of landmark points, so our algorithm has strong power in describing object details.

Computer-based geometry systems have been widely used for teaching and learning, but largely based on mouse-and-keyboard interaction, these systems usually require users to draw figures by following strict task structures defined by menus, buttons, and mouse and keyboard actions. Pen-based designs offer a more natural way to develop geometry theorem proofs with hand-drawn figures and scripts. This paper describes a pen-based geometry theorem proving system that can effectively recognize hand-drawn figures and hand-written proof scripts, and accurately establish the correspondence between geometric components and proof steps. Our system provides dynamic and intelligent visual assistance to help users understand the process of proving and allows users to manipulate geometric components and proof scripts based on structures rather than strokes. The results from evaluation study show that our system is well perceived and users have high satisfaction with the accuracy of sketch recognition, the effectiveness of visual hints, and the efficiency of structure-based manipulation.

The ability to recognize users and their intention during the visual analysis process is important to interact intelligently and effortlessly in a cooperative environment. In this paper, we present the framework for creating and modifying a concept map that allows analysts to collaborate and utilize live collection of enterprise data in a visual interface. Based on modeling users and tasks in visual analysis, a user model supporting collaborative analysis is given. Furthermore, we propose the algorithm of concept map layout to facilitate the visual analysis. The interface presents the analyst with the dashboard configuration of certain data that users deems relevant, provides tools to facilitate the decision making process. Finally, we apply it to a collaborative visual decision support system. Experimental results show that it enhances the accessibility and the individualization of collaborative concept map for configuring enterprise data and helps to enhance user experience during the visual analysis process.

This article presents UCFM, a user-centered developing framework for interactive temporal data visualization. UCFM is comprised mainly by software architecture and software development methods. The software architecture describes modules in interactive temporal data visualization system and their relationships. And based on the software architecture and development practice, the software development methods summarize these specific steps to design and develop interactive temporal data visualization system. To demonstrate UCFM's validity, the development process of an interactive temporal data visualization application is illustrated.

Concept maps are an important tool to knowledge organization, representation, and sharing. Most current concept map tools do not provide full support for hand-drawn concept map creation and manipulation, largely due to the lack of methods to recognize hand-drawn concept maps. This paper proposes a structure recognition method. Our algorithm can extract node blocks and link blocks of a hand-drawn concept map by combining dynamic programming and graph partitioning and then build a concept-map structure by relating extracted nodes and links. We also introduce structure-based intelligent manipulation technique of hand-drawn concept maps. Evaluation shows that our method has high structure recognition accuracy in real time, and the intelligent manipulation technique is efficient and effective.

We present a new technique called 'Tilt Menu' for better extending selection capabilities of pen-based interfaces. The Tilt Menu is implemented by using 3D orientation information of pen devices while performing selection tasks. The Tilt Menu has the potential to aid traditional one-handed techniques as it simultaneously generates the secondary input (e.g., a command or parameter selection) while drawing/interacting with a pen tip without having to use the second hand or another device. We conduct two experiments to explore the performance of the Tilt Menu. In the first experiment, we analyze the effect of parameters of the Tilt Menu, such as the menu size and orientation of the item, on its usability. Results of the first experiment suggest some design guidelines for the Tilt Menu. In the second experiment, the Tilt Menu is compared to two types of techniques while performing connect-the-dot tasks using freeform drawing mechanism. Results of the second experiment show that the Tilt Menu perform better in comparison to the Tool Palette, and is as good as the Toolglass.

Chinese text entry is challenging on mobile devices which rely on keypad input. Entering one character may require many key presses. This paper proposes a multimodal text entry technique for Chinese. In this method, Chinese user can enter Chinese text by simultaneously using the simplified phonemic input method named Jianpin with keypad and speech utterance. The key of the technique is a multimodal fusion algorithm, which synchronizes speech and keypad input and fuses redundant information from two modalities to get the best candidate. A preliminary evaluation shows that users appreciate this technique and it could reduce key presses and enhance the input efficiency.

In order to improve stimulus-response compatibility of touchpad in pen-based user interface, we present the tilt cursor, i.e. a cursor dynamically reshapes itself to providing the 3D orientation cue of pen. We also present two experiments that evaluate the tilt cursor's performance in circular menu selection and specific marking menu selection tasks. Results show that in a specific marking menu selection task, the tilt cursor significantly outperforms the shape-fixed arrow cursor and the live cursor [4]. In addition, results show that by using the tilt cursor, the response latencies for adjusting drawing directions are smaller than that by using the other two kinds of cursors.

In recognition-based user interface, users' satisfaction is determined not only by recognition accuracy but also by effort to correct recognition errors. In this paper, we introduce a crossmodal error correction technique, which allows users to correct errors of Chinese handwriting recognition by speech. The focus of the paper is a multimodal fusion algorithm supporting the crossmodal error correction. By fusing handwriting and speech recognition, the algorithm can correct errors in both character extraction and recognition of handwriting. The experimental result indicates that the algorithm is effective and efficient. Moreover, the evaluation also shows the correction technique can help users to correct errors in handwriting recognition more efficiently than the other two error correction techniques.

Gesture input is a natural and effective interactive model. The tracking of deformable hand gesture is a very important task in gesture-based interaction. A novel real-time tracking approach is proposed to capture hand motion with single camera. It combines the characters of model-based and appearance-based method. The presented approach achieves auto-initialization by posture recognition and matching with image features. It solves the problem of interference among fingers successfully by the integration of K-Means clustering and Particle Filters. Moreover, tracking detection realizes resumption from tracking failure and automatic update of hand model. Experiments show that, the proposed method can achieve continuous real-time tracking of deformable hand gesture, and meets the requirements for gesture-based Human-Computer Interaction.

In this paper a novel approach is described for tree visualization using nested circles. The brother nodes at the same level are represented by externally tangent circles; the tree nodes at different levels are displayed by using 2D nested circles or 3D nested cylinders. A new layout algorithm for tree structure is described. It provides a good overview for large data sets. It is easy to see all the branches and leaves of the tree. The new method has been applied to the visualization of file systems.

Co-CreativePen toolkit is a pen-based 3D toolkit for children cooperatively designing virtual environment. This toolkit is used to construct different applications involved with distributed pen-based 3D interaction. In this toolkit, sketch method is encapsulated as kinds of interaction techniques. Children can use pen to construct 3D and IBR objects, to navigate in the virtual world, to select and manipulate virtual objects, and to communicate with other children. Children can use pen to select other children in the virtual world, and use pen to write message to children selected. The distributed architecture of Co-CreativePen toolkit is based on the CORBA. A common scene graph is managed in the server with several copies of this graph are managed in every client. Every changes of the scene graph in client will cause the change in the server and other client

Raw digital ink is informal and unstructured. Its editing, especially its selection, is often inefficient. In this paper, we present approaches to structuralize raw digital ink as multiple hierarchies to facilitate its selection. First a link model is built to organize ink as a mesh-like structure. Based on the link model, the isolated stroke groups form patches. In each patch, textual and graphical areas are separated. Then, each textual area is segmented into text lines, and each text line is partitioned to words. We also design gestures for selecting structured ink. Experiments showed that our ink-structuralizing approaches are effective and selecting structured ink by our gestures considerably outperforms selecting raw ink.

In this paper, we describe a multimodal error correction mechanism. It allows the user to correct errors in continuous handwriting recognition naturally by simultaneously using pen gesture and speech. A multimodal fusion algorithm is designed to enhance recognition accuracies of handwriting and speech through cross-modal influence. We have performed preliminary evaluation experiments and the results show that this multimodal mechanism can efficiently correct the errors in continuous handwriting recognition.

The extraction of component line segments and circular arcs from freehand strokes along with their relations is a prerequisite for sketch understanding. Existing approaches usually take three stages to segment a stroke: first identifying segmentation points, then classifying the substroke between each pair of adjacent segmentation points, and, finally, obtaining graphical representations of substrokes by fitting graphical primitives to them. Since a stroke inevitably contains noises, the first stage may produce wrong or inaccurate segmentation points, resulting in the wrong substroke classification in the second stage and inaccurately fitted parameters in the third stage. To overcome the noise sensitivity of the three-stage method, the segmental homogeneity feature is emphasized in this paper. We propose a novel approach, which first extracts graphical primitives from a stroke by a connected segment growing from a seed-segment and then utilizes relationships between the primitives to refine their control parameters. We have conducted experiments using real-life strokes and compared the proposed approach with others. Experimental results demonstrate that the proposed approach is effective and robust.

Cooperative design is one of the most important subjects of the researches on CSCW. Distributed cognition is a useful theoretical framework applied to analyzing, designing, implementing, and evaluating cooperative design systems. In this paper, we construct a detailed distributed cognition framework, explain these terms in it, and implement a prototype of the cooperative design system, smart cooperative design system (SCDS), based on the framework. In SCDS, the computer can infer not only local participant intent but also team intent by capturing information distributed external environment and individual historical interactions. Cooperative participants can learn the intent each other through information representation distributed over individuals and artifacts. In some extent, this avoids some collaborative conflict.

Innovation on 3D shape design relies on advanced product design theory and effective design tools. The requirements for design tools mainly include collaborative performance and natural performance of interaction. In this paper, a 3D collaborative editing environment based on interactive transaction log is put forward and moreover the system architecture is presented. The collaborative mechanism is discussed and the collision detection of manipulation and application strategy during the course of multi-user concurrency editing is studied, the interactive gesture appropriate to 3D model and application methods are studied too. Finally a prototype system is built, which obtains satisfied result in practice.

On-line synchronous sketch recognition has the advantages of convenient input and natural interaction. But among the existing algorithms, some are just able to process simple sketches, and some have so high computational complexity as not to satisfy the real-time demand. In order to solve the problem of efficiency and coverage, a sketch recognition algorithm based on incremental intention extraction is presented. By defining the lag window, the algorithm understands the sketch intention of users on the base of incremental intention extraction. Moreover, the algorithm can update the existing intention sections according to the latest information in order that the recognition results are in line with the sketch intention of users. Experiments show that, the algorithm can recognize kinds of sketches in real time.

Summary form only given. Many researches have been devoted to designing appropriate concurrency control algorithms for real-time database systems, which not only satisfy consistency requirements but also meet transaction timing constraints as much as possible. Optimistic concurrency control protocols have the nice properties of being nonblocking and deadlock-free, but they have the problems of late conflict detection and transaction restarts. Although the number of transaction restarts is reduced by dynamic adjustment of serialization order (DASO) in real-time database systems, it still has some unnecessary transaction restarts. We first propose a new method called dynamic adjustment of execution order (DAEO) and a new optimistic concurrency control algorithm based on DAEO, which can reduce the number of unnecessary restarts near to zero and outperforms the previous algorithms, and then discuss the experiments and the results.

Informal presentations are a lightweight means for fast and convenient communication of ideas. People communicate their ideas to others on paper and whiteboards, which afford fluid sketching of graphs, words and other expressive symbols. Unlike existing authoring tools that are designed for formal presentations, we created SketchPoint to help presenters design informal presentations via freeform sketching. In SketchPoint, presenters can quickly author presentations by sketching slide content, overall hierarchical structures and hyperlinks. To facilitate the transition from idea capture to communication, a note-taking workspace was built for accumulating ideas and sketching presentation outlines. Informal feedback showed that SketchPoint is a promising tool for idea communication.

Ubiquitous computing provides the new research challenges for the next generation interactions. Natural User Interface is one of the important aspects. Pen and paper are the natural and simple tools to use in our daily life, which can fit for the imprecise and flexible design mode in conceptual design. Gestures are the useful and natural mode in the pen-based interaction which can be introduced and used through the similar mode to the existing resources in interaction. Inherent problems exist with collaborative conceptual design because the simultaneous group interaction required for users to smoothly and effectively work together in the same virtual space. In this paper, we provide solutions to these problems by devising a fast and direct gesture-based user interface, a set of visual effects that better enable a user's awareness of the operations done by other participants, and a set of tools for enhancing visual communication between participants. A gesture description language (GDL) is given to provide the useful gestures to the applications conveniently.

Conceptual design has played a very important role in the design process. Knowledge of all the design requirements and constraints during this early phase of a product's life cycle is usually approximate, imprecise, and unknown. Conceptual design is now recognized as a highly important process when considering both the concurrent engineering aspects and the commitment of resources necessary to design and develop a product. With the development of the Internet, collaborative design is imperative and effective. The technology of CSCW is adopted widely and necessarily in the domain of conceptual design. It can fit the nature of the design. It shortens the distance of designers in different places and collects and shares all the information in time. In conceptual design, collaborative design mainly includes function, principle, layout and initial structure, etc. We developed a system of conceptual design based on the current CAD system, which realized the seamless link with later detail design. For individual design, multi-modal technology, which integrates many interactions such as gesture and speech, supports an advanced interface to assist humans in developing applications.