Sang Chul Ahn

• Korea Institute of Science and Technology

In this paper, we investigate the requirements for fully asymmetric remote collaboration and present a prototype system. Unlike previously studied asymmetric remote collaboration systems, fully asymmetric remote collaboration handles the cases where a user of one side is a complete novice having difficulty in explaining his/her problems and unfamil...

We present a depth-based fingertip recognition method for interactive projectors. We use a depth camera attached to a projector, so it is possible to change the relative pose between the projector and the projection surface without manual recalibration. For detection and classification of fingertips, we propose to use cascaded random forests booste...

Facial modelling is a fundamental technique in a variety of applications in computer graphics, computer vision and pattern recognition areas. As 3D technologies evolved over the years, the quality of facial modelling greatly improved. To enhance the modelling quality and controllability of the model further, parametric methods, which represent or m...

This paper presents a fast but robust method to recognize articulated hand pose from single depth images in real-time. We tackle the main challenges in the hand pose recognition, which include the high degree of freedom and self-occlusion of articulated hand motion, using efficient retrieval of a large set of hand pose templates. The normalized ori...

A method of reconstructing a three-dimensional (3D) facial shape with super resolution even from a short moving picture having a front facial image by acquiring a super-resolution facial image by applying, as a weighting factor, a per-unit-patch similarity between a target frame and frames remaining after excluding the target frame from among a plu...

Since the character expressions are high dimensional, it is not easy to control them intuitively with simple interface. So far, existing controlling and animating methods are mainly based on three dimensional motion capture system for high quality animation. However, using the three dimensional motion capture system is not only unhandy but also qui...

We present a new framework that reconstructs a 3D surface by incorporating a color image into sparse depth points. Assuming that the image intensity change is highly correlated with the scene geometry, we first generate a planar mesh on the image using color variation, and then, we unproject the triangulated image to the world space by integrating...

This paper presents a handheld augmented reality (AR) system and an authoring method which provides alive contents in large targets. In the general augmented reality tools, they are not designed for large targets but for only adequate size of target which fits in the screen. Therefore we designed and built a vision-based AR system and an authoring...

We present a novel hand gesture interaction method which has a long-range working space (1m~5m) overcoming conventional approaches’ limitations in cost-performance dependency. Our camera-free interaction system is composed of a pair of lighting device and an instrumented glove with photosensor markers. The lighting devices spatiotemporally encode u...

Disclosed herein are a UPnP control point and a UPnP device based on the UPnP network and a connecting method using the same, in which a service connection is performed. The service connection is restrictedly performed using a configuration file defined to allow or deny a connection with a specific device on the UPnP network, so that only devices s...

Spin-images have been widely used for surface registration and object detection from range images in that they are scale, rotation, and pose invariant. The computational complexity, however, is linear to the number of spin images in the model data set because valid candidates are chosen according to the similarity distribution between the input spi...

Reusing robot applications in diverse robots is one of the important issues for robot platform. Due to diverse robot hardware configurations, however, providing compatibility of robot applications is not easy. In this paper, we propose a software component replacement method which changes application profiles to provide software compatibility. By r...

Consumer depth cameras such as Kinect are gaining huge popularity due to their potential to real-time 3D surface reconstruction. The creation of tractable 3D object models from the reconstructed surface model, however, requires further processings for segmentation, mesh/texture generation, and skeletal rigging. Providing solutions for all these iss...

Super-resolution using web images is a challenging problem because accurate motion estimation is difficult due to their viewpoint change and photometric variation. To overcome such difficulties, this paper formulates a unified framework where local color correction is incorporated into fuzzy motion estimation after global registration. Thus, both g...

There are growing needs for the 3D environment. The 3D devices, such like 3D television, have already started to be sold in markets to the general public. In other words, it means that D environment is becoming accustomed to everything. In the same manner, the ways for the 3D manipulation are also getting more important, and there are lots of ways...

In this paper we propose a new mobile augmented-reality system that will address the need of users in viewing baseball games with enhanced contents. The overall goal of the system is to augment meaningful information on each player position on a mobile device display. To this end, the system takes two main steps which are homography estimation and...

Due to the benefits of its reusability and productivity, the component-based approach has become the primary technology in service robot software frameworks, such as MRDS (Microsoft Robotics Developer Studio), RTC (Robot Technology Component), ROS (Robot Operating System) and OPRoS (Open Platform for Robotic Services). However, all the existing fra...

Typical photo-based augmented reality applications match photos against contents in a database of images, using image retrieval algorithms. Further, in such augmented reality applications, content authoring is a tedious and expensive task that requires specialized skills. Consequently, scaling database contents is hard, which results in lack of dat...

UPnP (Universal Plug and Play) is widely used to organize home network systems because of its straightforward implementation. However, UPnP networks are based only on TCP/IP, and operation proceeds within a single IP subnet. Previously, no mechanism was available to combine two UPnP networks via non-IP communication. Here, we report the implementat...

This paper presents new interaction method to control panorama video using head tracking technique. The panorama video viewer includes head tracking module which controls the rotation and forward/backward of the viewpoint. We applied this interaction technique to panorama video, which has omnidirectional gaze, to maximize realistic and immersive fe...

Due to the benefits of reusability and productivity, component-based approach has become the primary technology in service robot system development. However, because component developer cannot foresee the integration and operating condition of the components, they cannot provide appropriate fault tolerance function, which is crucial for commercial...

The OPRoS (Open Platform for Robotic Services) framework is proposed as an application runtime environment for service robot systems. For the successful deployment of the OPRoS framework, fault tolerance support is crucial on top of its basic functionalities of lifecycle, thread and connection management. In the previous work [1] on OPRoS fault tol...

For commercial success of emerging service robots, the fault tolerant technology for system reliability and human safety is crucial. Traditionally fault tolerance methods have been implemented in application level. However, from our studies on the common design patterns in fault tolerance, we argue that a framework-based approach provides many bene...

We propose a new method to recognize a user’s activities of daily living with accelerometers and RFID sensor. Two wireless accelerometers are used for classification of five human body states using decision tree, and detection of RFID-tagged objects with hand movements provides additional instrumental activity information. Besides, we apply our act...

This paper deals with a real-time image based relighting system for tangible video teleconference. The proposed image based relighting system renders the extracted human object using the virtual environmental images. The proposed system can homogenize virtually the lighting environments of remote users on the video teleconference, or render the hum...

We are currently developing a new tour guide service on mobile phone using augmented reality. Among the components for the service, in-situ annotation is one of the most important components for capturing of lots of personal experiences in the form of digital multimedia during his/her trip. Our in-situ annotation system provides several pieces of f...

In home-network system, UPnP Network is widely used because of simple usage. However, UPnP network is only based on TCP/IP and working in the same subnets. Many applications need extended communication. In this research, we implemented a UPnP bridge which binds two different networks into a virtually single UPnP network. This allows a control point...

The UPnP is middleware architecture that supports dynamic distributed computing environment. It has many good features for possible use as middleware in robot system integration. There is a need for bulky binary data transmission between distributed robot S/W components. Since the UPnP utilizes SOAP protocol for message transmission, however, it is...

We propose a novel method to recognize a user¿s activities of daily living with accelerometers and RFID sensor. Two wireless accelerometers are used for the classification of 5 human body states using decision tree, and detection of RFID tagged objects with hand movement provides additional object related hand motion information. To do this, we use...

This paper proposes robotic technology component with UPnP (Universal Plug and Play) communication. This research uses RTC (robotic technology component) specification that has been standardized by object management group (OMG). The modularity of robot component lets the robot developer to design their own interface communication. UPnP as communica...

This paper presents a new method for recognizing the activities of daily living (ADL) based on the state-dependent motion analysis using three accelerometers and a glove type RFID reader. Two accelerometers are used for the classification of five body states based on the decision tree. Classification of the instrumental activities is performed base...

Personal Lifelog media system involves capturing of great amount of personal experiences in the form of digital multimedia during an entire lifespan. However, the usefulness of those data is limited by lack of adequate methods for accessing and indexing such a large database. It is important to manage those data systematically so that user can effi...

In this paper, we present a tele-meeting system which uses an augmented robot agent as the representation of the remote participant. In this system, we augment a 3D volume video of the remote participant over the on-site robot. The robot agent in this system represents a remote user with camera, microphone, and mobility. Using this robot agent, the...

In this paper, we present an large-scale stereo display wall system for tangible telemeeting using programmable graphics hardware. For tangible telemeeting, it is important to provide immersive display with high resolution image to cover up the field of view and provide to the local user the same environment as that of remote site. To achieve these...

A robust recognition of ADL(Activities of Daily Living) based on human motion and object identification has proposed. Two wireless accelerometers are used for the classification of 5 human body states using decision tree, and detection of RFID tagged objects with hand movement provides additional object related hand motion information. To do this,...

In this paper, we present an efficient tiled stereo display system for tangible meeting. For tangible meeting, it is important to provide immersive display with high resolution image to cover up the field of view and provide to the local user the same environment as that of remote site. To achieve these, a high resolution image needs to be transmit...

This article presents an implementation of a real-time dynamic 3D avatar from multiview cameras for immersive telecommunication. Immersive telecommunication is a new challenging field that enables a user to share a virtual space with remote participants, providing users with a sense of telepresence and interaction. The main objective is to offer ri...

This paper presents our simple and easy to use method to obtain a 3D textured model. For expression of reality, we need to integrate the 3D models and real scenes. Most of other cases of 3D modeling method consist of two data acquisition devices. In this case, the former device would be 2D laser range-finder and the latter device would be common ca...

The UPnP (universal plug and play) defines an architecture for pervasive peer-to-peer network connectivity of intelligent appliances. It shares the service oriented architecture with emerging Web service technology, and has many advantages for future robot middleware such as automatic discovery of services and accommodation of dynamic distributed c...

This paper presents our simple and easy to use method to obtain a 3D textured model. For expression of reality, we need to integrate the 3D models and real scenes. Most of other cases of 3D modeling method consist of two data acquisition devices. One is for getting a 3D model and another for obtaining realistic textures. In this case, the former de...

This paper presents a new computer supported remote learn- ing and gaming method using Tele-Face Mouse system. The Tele-Face Mouse system is being developed as a teleconference system. It converts simple desktop computers to a teleconference system. The main advan- tage of the Tele-Face Mouse system is that it enables people to share a computer scr...

In this paper, we suggest that we can use our mobile devices as an effective interface for HMD-based augmented reality (AR) applications. These days most of us can possibly send short message with our mobile phones and watch the movies on our PDAs. Personal hand-held devices are well customized that they deserve to be familiar interfaces for intera...

In this paper, we propose new system for storing and re- trieval of personal life log media on ubiquitous environment. We can gather personal life log media from intelligent gadgets which are con- nected with wireless network. Our intelligent gadgets consist of wearable gadgets and environment gadgets. Wearable gadgets include audiovisual device, G...

We present a new system for creation and efficient retrieval of personal life log media(P-LLM) on networked environment in this paper. Personal life log media data include audiovisual data for user's experiences and additional data from intelligent gadgets which include multimodal sensors, such as GPS, 3D-accelerometers, physiological reaction sens...

The UPnP (universal plug and play) technology was devised for pervasive peer-to-peer network connectivity of PCs and intelligent appliances. It shares the service oriented architecture with emerging Web service technology. It also has many advantages for future robot middleware such as automatic discovery of services and accommodation of dynamic di...

Immersive telecommunication is a new challenging field that enables a user to share a virtual space with remote participants. The main objective is to offer rich communication modalities, as similar as those used in the face-to-face meetings like gestures, gaze awareness, realistic images, and correct sound direction. Moreover, natural full body in...

Immersive telecommunication is a new challenging field that enables a user to share a virtual space with remote participants. The main objective is to offer rich communication modalities, as similar as those used in the face-to-face meetings like gestures, gaze awareness, realistic images, and correct sound direction. Moreover, full body interactio...

In this paper, we propose a new method of removing glasses from a human frontal facial image. We first detect the regions occluded by the glasses and generate a natural looking facial image without glasses by recursive error compensation using PCA reconstruction. The resulting image has no trace of the glasses frame or of the reflection and shade c...

This paper presents an approach to utilize UPnP as a middleware for robots. It describes the advantages of UPnP by comparing UPnP with TAO CORBA that was used in a few robot development projects. In order to consider real situation, we select a sample robot architecture, and examine the possibility of UPnP as a robot middleware with the robot archi...

In this paper, we present the new environment for telexistence using our smart space which we have built for interactive space. We've developed several component modules for telexistence, such as display module for large scale display system, interaction module for multimodal interaction, video module for streaming and rendering module for augmente...

We present a simple and successful design for network-based tiled display system to solve the problems that previous approaches which depend on a special platform and library to make contents of tiled display system. We have developed the proposed system using GPU based real-time warping with camera based automatic feature extraction method, blendi...

This paper proposes a 3-dimensional (3D) voice over IP (VoIP) system for two user groups with the smallest device requirements. It also presents design issues of the system and some experience in implementation of the system. The proposed system requires only a desktop computer with a multi-channel soundcard installed, USB microphones as many as th...

This paper presents a new computer-based teleconference system. In order to build the system, we modified VNC(Virtual Network Computing) program and implemented Face mouse system. Face mouse is a mouse pointer that is followed by face video. It has multiple functions of video communication channel, mouse identification, and a connection between fac...

An improved segmentation method of the human body with optical IR-keying and image-based active illumination is presented. This approach provides effective generation of photo-realistic live avatars in an immersive display environment for tele-interaction.

This paper presents a new system for interacting with a large display using live video avatar of a user and hand gesture recognition. The system en- ables a user to appear on a screen as a video avatar and to interact with items therein. The user can interact with the large display remotely by walking and touching icons through his video avatar. In...

This paper presents real-time reconstruction of dynamic 3D avatar for interactive mixed reality. In computer graphics, one of the main goals is the combination of virtual scenes with real-world scenes. However, the views of the real world objects are often restricted to views from the cameras. True navigation through such mixed reality scenes becom...

This paper presents a smart location tracking system using FSR(Force Sensing Resistor). It is important to note that our system doesn't need to attach a sensor to human body, because we install a FSR in a floor in order to establish a smart space. Our system can track location of a person and interact with a computer through tapping behavior of per...

This paper proposes a new method of removing glasses from human frontal face images. We first detect regions occluded by glasses. Then we generate a naturally looking glassless facial image by recursive PCA reconstruction. The resulting image has no trace of glass frame, nor the reflection and shade made by the glasses. The experimental results sho...

We have built the world's largest virtual reality (VR) theater for the Gyeongju World Culture EXPO 2000. The VR theater is characterized by a huge shared VR space with tightly coupled user inputs from 651 audience members in real time. The shared D virtual environment is augmenting the physical audience space in harmony. Large computer-generated pa...

Recently we have built the largest Virtual Reality (VR) theatre in the world of the Kyongju World Culture EXPO 2000. Unlike single user VR systems, the VR theatre is characterized by a single shared screen and controlled by several hundreds of people in the audience. The large computer-generated stereo images displayed by the huge cylindrical scree...

This paper concerns extracting 3D motion information from a 3D input device in real time focused to enabling effective human-computer. interaction. In particular, we develop a novel algorithm for extracting 6 degrees-of-freedom motion information from a 3D input device by employing an epipolar geometry of stereo camera, color, motion, and structure...

Recently we have built the largest Virtual Reality (VR) theatre in the world for the Kyongju World Culture EXPO 2000. Unlike single user VR systems, the VR theatre is characterized by a single shared screen and controlled by a kind of tightly coupled user inputs from several hundreds of people in the audience. The large computer-generated stereo im...

This paper analyzes the number of operations and parameters of general fuzzy logic control algorithms. And limitations of loop controllers to implement the fuzzy logic control are investigated in terms of computation time and required memory. Using analysis of general fuzzy logic control algorithms, it is shown that general fuzzy logic control algo...

This paper introduces web-based 3D media information system. We first address two promising 3D modeling techniques, i.e., image-based 3D modeling and laser scanning based 3D modeling. Especially, we present two approaches of the image-based 3D modeling. One is an off-line approach using multiview images which is captured with single camera and a ro...

This paper proposes a new object tracking algorithm called the MAWUPC (motion adaptive weighted unmatched pixel count) algorithm for solving complex background and occlusion problems and for proposing a more effective combination of color and motion information. The proposed algorithm incorporates color transform, Kalman filter and UPC operation to...

We present a 3D tracking method of multi-objects by color and stereo. The results are applied to navigation and manipulation in a virtual environment. We choose a human face and hands as tracking targets for HCI. To extract the area of face and hands in a complex background, we transform an input color image using the GSCD (generalized skin color d...

This paper addresses three research issues for the virtual heritage system: 3D modeling, 3D media asset database management, and interactive presentation through networks. We first show art overview of our virtual heritage system and introduce our approaches on each research issue. We develop 3D modeling environment using both of two emerging techn...

Recently we have built a VR(Virtual Reality) theater in Kyongju, Korea. It combines the advantages of VR and IMAX theater. The VR theater can be characterized by a single shared screen and by multiple inputs from several hundreds of people. In this case, multi-user interaction is different from that of networked VR systems and must be reconsidered....

This paper presents an automatic FDP (Facial Definition Parameters) and FAP (Facial Animation Parameters) generation method from an image sequence that captures a frontal face. The proposed method is based on facial feature tracking without markers on a face. We present an efficient method to extract 2D facial features and to generate the FDP by ap...

This paper summarizes and investigates relations of a number of bounds for the solutions of the algebraic Riccati and Lyapunov equations which have been reported during the last two decades. Also presented are bounds for the unified Riccati equation using the delta operator and it is shown that some bounds for the continuous and discrete Riccati eq...

This paper proposes an object oriented face detection method using range and color information. Objects are segmented from the background using the stereo disparity histogram that represents the range information of the objects. A matching pixel count (MPC) disparity measure is introduced to enhance the matching accuracy, and removes the effect of...

This paper analyzes the performance degradation of the IEEE 802.4 token bus network in a noisy environment where clustered noises are generated with non-zero durations. The operation of the token passing mechanism in a token bus network is modeled by a state machine considering the effects of noise, and then the detailed token passing operation und...

In this paper a fuzzy generalized predictive control (FGPC) for nonlinear plants is proposed. In the proposed method, the receding horizon control is applied to the control part, while fuzzy systems are used for the predictor part. It is suggested that the fuzzy predictor is time-varying affine with respect to input variables for easy computation o...

A new method of extracting depth from blurring and magnification of objects or local scene is presented. Assuming no active illumination, the images are taken at two camera positions of a small displacement, using a single standard camera with telecentric lens. Thus, the depth extraction method is simple in structure and efficient in computation. F...

A new method of extracting depth from blurring and magnification of objects or local scene has been presented. Assuming no active illumination, the images are taken at two camera positions of a small displacement, using a single standard camera with telocentric lens. Thus, the depth extraction method is simple in structure and efficient in computat...

A new method of constructing 3D maps based on the relative magnification and blurring of a pair of images is presented, where the images are taken at two camera positions of a small displacement. The method, referred to as depth from magnification and blurring, aims at generating a precise 3D map of local scenes or objects to be manipulated by a ro...

This paper summarizes and investigates the relations of a number of bounds for the solutions of the algebraic Riccati and Lyapunov equations that have been reported during the last two decades. Also presented are bounds for the unified Riccati equation using the delta operator and it is shown that some bounds for the continuous and discrete Riccati...

In this paper the computational complexity of fuzzy controls is investigated. By analyzing fuzzy control programs, the computational requirements are computed for a few methods of fuzzy controls. The computational requirements are classified in terms of basic operations to be executed. From these results, it is shown that general fuzzy controls are...

A new stability test method for linguistic fuzzy state space models is proposed in this paper. This method allows the determination of stability of fuzzy models by applying the Lyapunov function to each rule. A gradient-based algorithm is suggested to simplify the stability tests. Using this algorithm, the Lyapunov equation can be updated towards t...

The upper and lower bounds for the mean cycle time and the mean message transmission time of class six and class four in the IEEE 802.4 token bus network, within which the minimum utilization constraint of class four is guaranteed, are derived. Stability conditions for the token bus network are also derived. These bounds and stability conditions ar...

We present a low cost but practical stereo vision based tracking system for VR/AR applications. In order to achieve high performance, robustness and accuracy of the system under real-time constraint, we developed ARToolKit using stereo camera and applied to our tracking system. The presented tracking system is based on two IEEE 1394 cameras (equipp...

We present a volumetric visual hull-based tangible video avatar for natural interaction. Proposed approach is a new challenging field that enables a user to share a remote space with virtual tangibility. The main objective is to offer rich interaction modalities, as similar as those used in the real world. As a result, the user can be immersed and...

We present a system for tangible interface using real-time 3D video avatar. Proposed tangible interface is a new challenging field that enables a user to share a virtual space with real objects. The main objective is to offer rich interaction modalities, as similar as those used in the real world. As a result, the user can be immersed and has inter...