Mee Young Sung

Experiments for a Collaborative Haptic Virtual Reality

In this paper, we present preliminary results of our ongoing networked virtual reality project by discussing the implementation and performance of a networked haptic game. In this game, online players feel like handling a real basketball since they are able to feel the sense of touch by using haptic interfaces. One of challenging issues in this implementation is haptic data transmission over the Internet to allow online multi-user play. Since haptic information is extremely sensitive to delay and jitter, the provision of timely transmission is critical. We carry out experiments to compare the performance of the haptic data transmission when using UDP (User Datagram Protocol) and TCP (Transmission Control Protocol), and observe that neither UDP nor TCP is able to satisfy QoS (Quality of Service) requirements of the haptic transmission. As a further study, we plan to investigate some alternative haptic data transmission schemes.

A collaborative authoring system for multimedia presentation

We propose a collaborative authoring system for multimedia presentation. Our multimedia authoring system benefits greatly from a 3D spatiotemporal interface which intuitively represents the multimedia presentation in one seamless environment. Our system is composed of an editing system, a media object manager and a collaboration manager. The editing system contains two unique editors; a 3D spatiotemporal editor and a temporal relation network (TRN) editor, in addition to the traditional editors such as timeline editor, tag editor, attribute editor, and text editor. These editors are all shared over the Internet and together they form an easy and efficient multimedia authoring environment. Using our system, users in different places can author multimedia presentations in a unified spatiotemporal space while freely traversing the spatial domain and the temporal domain without changing the context of authoring. Our system also provides users with an intuitive mechanism for representing the conceptual flow of a presentation. We implemented some ideas for efficient concurrency control in our system. They are mainly based on user awareness, multiple versions, fine granularity of locking, and access permissions of shared objects. Some our experiments lead us to conclude that our system is more advantageous than traditional multimedia authoring systems in terms of authoring time and ease of interaction.

Steganography using block-based adaptive threshold

Steganography is a technique to hide secret information in some other data (we call it a vessel) without leaving any apparent evidence of data alteration. All of the traditional steganographic techniques have limited information-hiding capacity. In this paper, we proposed a new method of the adaptive steganography using complexity on bit planes of color image. Applying fixing threshold and variable length, if we insert information into all bit planes, all bit planes showed different image quality. Therefore, we investigated the complexity on bit plane and data, similarity insert information into bit planes. As a result, the proposed method increased the insertion capacity and improved the image quality as compared to fixing threshold and variable length method.

An Experimental Study on the Performance of Haptic Data Transmission in Networked Haptic Collaboration

In this paper, we present preliminary results of our ongoing networked virtual reality project by discussing the implementation and performance of an experimental haptic collaboration system; a networked haptic basketball game. In this game, online players feel like handling a real basketball since they are able to feel the sense of touch by using haptic interfaces. One of challenging issues in this implementation is haptic data transmission over the Internet to allow online multi-user play. Since haptic information is extremely sensitive to delay, jitter, and loss, the provision of timely transmission is critical. We carry out some experiments to compare the performance of the haptic data transmission under various delays, jitters, and losses of packets for two models; one is the position transfer model and the other is the force transfer model. We observe that loss of packets may reduce the force feedback in the Position Transfer Model and jitters are more sensitive than delays for both models.

Vision-Based real-time camera matchmoving with a known marker

A primary requirement for practical augmented reality systems is a method of accurate and reliable camera tracking. In this paper, we propose a fast and stable camera matchmoving method aimed for real-time augmented reality application. A known marker is used for the fast detection and tracking of feature points. From the feature tracking of one of three different types of markers on a single frame, we estimate the camera position and translation parameters. The entire pose estimation process is linear and initial estimates are not required. As an application of the proposed method, we implemented a video augmentation system that replaces the marker in the image frames with a virtual 3D graphical object during the marker tracking. Experimental results showed that the proposed camera tracking method is robust and fast enough to interactive video-based applications.

An Integrated Haptic Data Transmission in Haptic Collaborative Virtual Environments

Haptic collaboration virtual environment (HCVE) is an enhanced virtual reality space with haptic interface support. HCVE users are connected together over the network and are able to work together by using sense of touch, i.e. haptics as well as audio and visual interfaces. In HCVE, the communication of haptic data is challenging because of time-varying network conditions and extremely high data rate. To mitigate such difficulties, we propose a linear prediction algorithm and a buffering scheme which is an integrated scheme for haptic data transmission. The prediction algorithm is to minimize the negative effects from network delay, loss and jitter, while the buffering scheme is to easily synchronize haptic interaction. For the evaluation of our proposed schemes, we build an experimental test bed for HCVE. As the result, we observe that our schemes are effective in improving the quality of haptic experiences. The quantitative measurement results are presented.

Vision-Based bare-hand gesture interface for interactive augmented reality applications

This paper presents a barehanded interaction method for augmented reality games based on human hand gestures. Point features are tracked from input video frames and the motion of moving objects is computed. The moving patterns of the motion trajectories are used to determine whether the motion is an intended gesture. A smooth trajectory toward one of virtual objects or menus is classified as an intended gesture and the corresponding action is invoked. To prove the validity of the proposed method, we implemented two simple augmented reality applications: a gesture-based music player and a virtual basketball game. The experiments for three untrained users indicate that the accuracy of menu activation according to the intended gestures is 94% for normal speed gestures and 84% for fast and abrupt gestures.

Realtime control for motion creation of 3d avatars

In this paper, we are proposing a new mechanism for controlling 3D (three dimensional) avatars to create user-designed peculiar motions of avatars in real-time using general interfaces, such as a mouse, a keyboard, or a joystick. The main idea is based on the new way of interactive control that is the combined usage of keyboard and mouse simultaneously. In order to generate natural human motions of avatars, we adopted the center line concept of art drawing and some influencing physics algorithms which developed intensively in the field of biped humanoid robot research. We demonstrate that user-designed motions of avatar can be created in real-time using proposed interaction method with keyboard and mouse. Also, we show that a rich set of peculiar behaviors can be generated from a ready-made motion with motion capture data or created and stored in our system. Note that the generated peculiar motions can be more natural if we appropriately apply our center line concept and physics algorithms.

Reliable mobile ad hoc p2p data sharing

We developed a reliable mobile Peer-to-Peer (P2P) data sharing system and performed some experiments for verifying our routing scheme using our real testbed. Our method for guaranteeing reliable P2P data sharing mainly deals with the problem of disconnection due to the sudden disappearance of one or more nodes involved in the active transmission route. The routing scheme of our system allows for reliable transmission of data via mobile devices. It does this using our reconnection mechanism that finds emergency routes in instances of abrupt disconnection using our scanning table and lookup table. The experiments lead us to conclude that our communication method is effective and assures reliable P2P data sharing over mobile ad hoc networks. In addition, our system allows for finding directly connectable devices at the overlay networks, therefore the application program can distinguish whether the target node is directly accessible or not with the aid of our scanning table.

A java-based collaborative authoring system for multimedia presentation

In this paper, we propose a Java-based collaborative authoring system for multimedia presentation. Our system is composed of an Editing System, a Media Object Manager and a Collaboration Manager. The Editing System contains two unique editors; a 3D Spatio-Temporal editor and a Temporal Relation Network (TRN) editor, in addition to the traditional editors such as timeline editor, tag editor, attribute editor, and text editor. These editors are all shared over the Internet and together they form an easy and efficient multimedia authoring environment. Using our system, users in different places can author multimedia presentations in a unified spatio-temporal space while freely traversing the spatial domain and the temporal domain without changing the context of authoring. We also implemented some ideas for efficient concurrency control in our system. They are mainly based on user awareness, multiple versions, and access permissions of shared objects. Our work on the development of a Java-based collaborative authoring system leads us to conclude that the Java technology is a satisfactory tool for developing a collaborative authoring system including a 3D interface. However, the Java3D technology needs to be ameliorated in the aspect of performance.