• Korean Journal of Computational Design and Engineering
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• v.16 no.4
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• pp.277-284
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• 2011

In tangible augmented reality (AR) environments for virtual prototyping, the user interacts with virtual products by manipulating tangible objects with his or her hands, but the user often encounter awkward situations in which his or her hands are occluded by augmented virtual objects, which reduces both immersion and ease of interaction. In this paper, we present how to resolve such hand region occlusion in order to enhance natural interaction and immersive visualization. In the AR environment considered, we use two types (product-type and pointer-type) of tangible objects for tangible user interaction with a virtual product of interest. Holding the tangible objects with his or her hands, the user can create input events by touching specified regions of the product-type tangible object with the pointer-type tangible object. We developed a method for resolving hand region occlusion frequently arising during such user interaction, It first detect hand region in a real image and refines the rendered image of the virtual object by subtracting the hand region from the rendered image, Then, it superimposes the refined image onto the real image to obtain an image in which the occlusion is resolved. Incorporated into tangible AR interaction for virtual prototyping of handheld products such as cellular phones and MP3 players, the method has been found by a preliminary user study that it is not only useful to improve natural interaction and immersive visualization of virtual products, but also helpful for making the users experience the products' shapes and functions better.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.4
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• pp.618-632
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• 2010

This paper presents a novel approach to control the augmented reality (AR) objects robustly in a marker-less AR system by fingertip tracking and hand pattern recognition. It is known that one of the promising ways to develop a marker-less AR system is using human's body such as hand or face for replacing traditional fiducial markers. This paper introduces a real-time method to manipulate the overlaid virtual objects dynamically in a marker-less AR system using both hands with a single camera. The left bare hand is considered as a virtual marker in the marker-less AR system and the right hand is used as a hand mouse. To build the marker-less system, we utilize a skin-color model for hand shape detection and curvature-based fingertip detection from an input video image. Using the detected fingertips the camera pose are estimated to overlay virtual objects on the hand coordinate system. In order to manipulate the virtual objects rendered on the marker-less AR system dynamically, a vision-based hand control interface, which exploits the fingertip tracking for the movement of the objects and pattern matching for the hand command initiation, is developed. From the experiments, we can prove that the proposed and developed system can control the objects dynamically in a convenient fashion.

• Current Optics and Photonics
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• v.1 no.6
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• pp.642-648
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• 2017

Involuntary hand tremor has been a serious challenge in micromanipulation tasks and thus draws a significant amount of attention from related fields. To minimize the effect of the hand tremor, a variety of mechanically assistive solutions have been proposed. However, approaches increasing human awareness of their own hand tremor have not been extensively studied. In this paper, a head mount display based virtual reality (VR) system to increase human self-awareness of hand tremor is proposed. It shows a user a virtual image of a handheld device with emphasized hand tremor information. Provided with this emphasized tremor information, we hypothesize that subjects will control their hand tremor more effectively. Two methods of emphasizing hand tremor information are demonstrated: (1) direct amplification of tremor and (2) magnification of virtual object, in comparison to the controlled condition without emphasized tremor information. A human-subject study with twelve trials was conducted, with four healthy participants who performed a task of holding a handheld gripper device in a specific direction. The results showed that the proposed methods achieved a reduced level of hand tremor compared with the control condition.

• Journal of Korea Game Society
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• v.17 no.6
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• pp.113-120
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• 2017

With the development of virtual reality technology, in recent years, user-friendly hand gesture interface has been more studied for natural interaction with a virtual 3D object. Most earlier studies on the hand-gesture interface are using relatively simple hand gestures. In this paper, we suggest an intuitive hand gesture interface for interaction with 3D object in the virtual reality applications. For hand gesture recognition, first of all, we preprocess various hand data and classify the data through the binary decision tree. The classified data is re-sampled and converted to the chain-code, and then constructed to the hand feature data with the histograms of the chain code. Finally, the input gesture is recognized by MCSVM-based machine learning from the feature data. To test our proposed hand gesture interface we implemented a 'Virtual Block' game. Our experiments showed about 99.2% recognition ratio of 16 kinds of command gestures and more intuitive and user friendly than conventional mouse interface.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2003.05a
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• pp.84-89
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• 2003

The virtual reality(VR) technology can provide various stimuli, including, visual and auditory stimuli, simultaneously in the virtual environment and encourage the user to interact. Virtual reality is a set of computer technologies, which when combined, provide an interactive interface to a computer generated world. In this world the subject can see, hear and navigate in a dynamically changing environment in which he participates as an active player, by modifying the environment according to his will. Moreover, the subject can get a feeling for the virtual environment in much the same way as one feels real life situations. In the real world, a plethora of information from various modalities may be in conflict, and modulate each other to form an illusion. In this study we investigated whether a tactile illusion on a real hand could be evoked by a virtual stimulus, the time required to generate this illusion and its duration. This study shows that the illusion occurred, and that was correlated with presence score in the virtual environment.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.89.3-89
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• 2001

Recently computer graphic technology has achieved remarkable development. Applications of this technology to various fields are expected. In this study, one application of computer graphics to the medical field is shown. We developed a rehabilitation system of hand manipulation using virtual reality aiming to offer enjoyable rehabilitation training to physically handicapped people with upper limb disabilities. This rehabilitation system generates training environments for upper limbs, such as moving balls in virtual space of computer. And by using data glove as a sophisticated input device, a user can manipulate objects in virtual space by his hand. By using this rehabilitation system, a user can have rehabilitation training under various conditions without feeling tedious.

• Journal of Korea Game Society
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• v.10 no.2
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• pp.49-56
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• 2010

In this paper, we propose a control method of virtual hand by the recognition of a user's hand in the virtual reality game environment. We display virtual hand on the game screen after getting the information of the user's hand movement and the direction thru input images by camera. We can utilize the movement of a user's hand as an input interface for virtual hand to select and move the object. As a hand recognition method based on the vision technology, the proposed method transforms input image from RGB color space to HSV color space, then segments the hand area using double threshold of H, S value and connected component analysis. Next, The center of gravity of the hand area can be calculated by 0 and 1 moment implementation of the segmented area. Since the center of gravity is positioned onto the center of the hand, the further apart pixels from the center of the gravity among the pixels in the segmented image can be recognized as fingertips. Finally, the axis of the hand is obtained as the vector of the center of gravity and the fingertips. In order to increase recognition stability and performance the method using a history buffer and a bounding box is also shown. The experiments on various input images show that our hand recognition method provides high level of accuracy and relatively fast stable results.

• Journal of The Korean Digital Architecture Interior Association
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• v.6 no.2
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• pp.17-23
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• 2006

The purpose of this study was to investigate how student felt the strengths and shortness of presentation methods for formation of interior spaces. For this study, the process of the interior architecture design class was divided into three stages: the programming. the design development, and the design completion. In the design development stage, students used presentation methods: hand sketch, scale model, computer modeling, and virtual realty. The strengths of hand sketch was that quick expression. Models provided three-dimensional feelings. Computer modelling provide realistic color and texture. Virtual reality provided three-dimensional immersion and real scale. It is effective that students collect brain storm images using quick hand sketch in the beginning of design development stage. After that, they compose interior spaces in study models with small scale. Watching the models, they design details of spaces by using hand sketch and computer modelling. Using virtual reality, they can check the scale and circulation. Finally, they complete computer modelling by texture mapping and check the final design in virtual reality.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.1
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• pp.53-62
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• 2023

Purpose : This study evaluated the effects of transcranial direct current stimulation and a virtual reality program on the depression, hand functions, cognitive function, and activities of daily living of patients with mild cognitive impairment by dividing 20 patients with mild cognitive impairment and depression. The 20 patients were divided into a treatment group (transcranial direct current stimulation + a virtual reality program) and a control group (placebo transcranial direct current stimulation + a placebo virtual reality program). Methods : This study allocated ten subjects to the treatment group and ten subjects to the control group. The treatment was given five times per week for six weeks (30 sessions), and each session was 30 minutes. This study screened depression by using SGDS-K, a short geriatric depression scale, to examine depression before and after treatment intervention. This study also used the box and block test, NCSE, and FIM to evaluate hand functions, cognitive function, and activities of daily living, respectively. Results : The results showed that depression significantly decreased, hand functions significantly increased, cognitive function significantly improved, and activities of daily living significantly increased after intervention in the treatment and control groups. The magnitude of changes in depression, hand functions, cognitive function, and activities of daily living was significantly different between the two groups after intervention (p>.05). Conclusion : The results showed that the application of transcranial direct current stimulation and a virtual reality program could improve cognitive function, hand functions, and activities of daily living by decreasing depression. Therefore, it can be concluded that the simultaneous application of transcranial direct current stimulation and a virtual reality program is an intervention method, which can be applied for decreasing depression, enhancing hand functions, improving cognitive function, and increasing activities of daily living in patients with mild cognitive impairment.

• Korean Journal of Computational Design and Engineering
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• v.21 no.1
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• pp.20-30
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• 2016

Recently immersive virtual reality (VR) becomes popular due to the advanced development of I/O interfaces and related SWs for effectively constructing VR environments. In particular, natural and intuitive manipulation of 3D virtual objects is still considered as one of the most important user interaction issues. This paper presents a comparative study on the manipulation and interaction of 3D virtual objects using different interfaces and interactions in three VR environments. The comparative study includes both quantitative and qualitative aspects. Three different experimental setups are 1) typical desktop-based VR using mouse and keyboard, 2) hand gesture-supported desktop VR using a Leap Motion sensor, and 3) immersive VR by wearing an HMD with hand gesture interaction using a Leap Motion sensor. In the desktop VR with hand gestures, the Leap Motion sensor is put on the desk. On the other hand, in the immersive VR, the sensor is mounted on the HMD so that the user can manipulate virtual objects in the front of the HMD. For the quantitative analysis, a task completion time and success rate were measured. Experimental tasks require complex 3D transformation such as simultaneous 3D translation and 3D rotation. For the qualitative analysis, various factors relating to user experience such as ease of use, natural interaction, and stressfulness were evaluated. The qualitative and quantitative analyses show that the immersive VR with the natural hand gesture provides more intuitive and natural interactions, supports fast and effective performance on task completion, but causes stressful condition.