• ETRI Journal
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• v.38 no.2
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• pp.337-346
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• 2016

We propose a data-driven kinematic control method for a robotic spatial augmented reality (RSAR) system. We assume a scenario where a robotic device and a projector-camera unit (PCU) are assembled in an ad hoc manner with loose kinematic specifications, which hinders the application of a conventional kinematic control method based on the exact link and joint specifications. In the proposed method, the kinematic relation between a PCU and joints is represented as a set of B-spline surfaces based on sample data rather than analytic or differential equations. The sampling process, which automatically records the values of joint angles and the corresponding external parameters of a PCU, is performed as an off-line process when an RSAR system is installed. In an on-line process, an external parameter of a PCU at a certain joint configuration, which is directly readable from motors, can be computed by evaluating the pre-built B-spline surfaces. We provide details of the proposed method and validate the model through a comparison with an analytic RSAR model with synthetic noises to simulate assembly errors.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.137-147
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• 2007

Projection-based augmented reality (AR) system refers to the system that accurately project high quality virtual information at the user-specified area by using the projector. Most of projection-based AR systems use the display device to support high quality and wide screen for increasing the user-immersion. Furthermore, they are implemented on the desktop environment due to the computational complexity. However, these projection-based AR systems are not suited as a mobile system and thus it may be inconvenient in the user point of view. Fortunately, Miniaturization of projectors and improved capacity of the mobile processor allowed the mobile AR system to be convenient. The limitation of established mobile AR system is that it uses small display screen which does not support high-resolutions and thus it may reduce the user-immersion into the system. In this paper, we propose portable projection-based display system, which overcomes the limitations of both projection-based and mobile-based AR systems. We have conducted the user evaluation to verify the effectiveness and the utmost capacity of the system.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.2
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• pp.51-56
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• 2009

We developed an augmented new reality tool for vision-based hand gesture recognition in a camera-projector system. Our recognition method uses modified Fourier descriptors for the classification of static hand gestures. Hand segmentation is based on a background subtraction method, which is improved to handle background changes. Most of the recognition methods are trained and tested by the same service-person, and training phase occurs only preceding the interaction. However, there are numerous situations when several untrained users would like to use gestures for the interaction. In our new practical approach the correction of faulty detected gestures is done during the recognition itself. Our main result is the quick on-line adaptation to the gestures of a new user to achieve user-independent gesture recognition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1348-1353
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• 2007

We developed an augmented new reality tool for vision-based hand gesture recognition in a camera-projector system. Our recognition method uses modified Fourier descriptors for the classification of static hand gestures. Hand segmentation is based on a background subtraction method, which is improved to handle background changes. Most of the recognition methods are trained and tested by the same service-person, and training phase occurs only preceding the interaction. However, there are numerous situations when several untrained users would like to use gestures for the interaction. In our new practical approach the correction of faulty detected gestures is done during the recognition itself. Our main result is the quick on-line adaptation to the gestures of a new user to achieve user-independent gesture recognition.

• Journal of the Korea Society of Computer and Information
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• v.6 no.4
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• pp.104-109
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• 2001

In this paper, we designed a 3D shape measuring system with high speed and high measurement resolution using line-shaped sine stripes of a LCD projector We proposed an effective method to improve measurement efficiency for a 3D shape measuring system by finding the deficient shape information areas and recovering the shape information efficiently. We experimentally confirmed the improvement of measurement efficiency. Deficient shape information areas can be inevitably existed in a acquired image caused by the camera view angle and surface shapes of an object. The measurement efficiency is turned out to be improved by extracting these shadow areas and recovering the shape information efficiently using both a variable rated normalization and a variable sized phase recovering windows.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.4 s.316
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• pp.26-34
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• 2007

Intelligent projection system indicates a system that displays desired images on an arbitrary screen in an arbitrary environment using projector without noticeable image distortion. In recent years, projectors have become widespread and ubiquitous due to their increasing capabilities and declining cost. Moreover, the size of projectors is getting smaller and handhold projectors are emerging. Thanks to these advances, the demand for intelligent projection system has been significantly increased and the demand has led to remarkable progress of the related techniques or technologies to intelligent projection system However, there are still some environments (or conditions, mainly dynamic ones) that intelligent projections systems cannot handle and they have limited the application area of intelligent projection systems. This paper exemplifies such environments (e.g. specular screen, dynamic screen) and propose effective solutions (i.e. multiple overlapping projectors, complementary pattern embedding) for thor And the usefulness of the solutions is verified through experimental results and user evaluation. Notice that the environments are considered not simultaneously but independently because it is impossible to consider them simultaneously by simply combining the solutions for each. Acually, a totally different solution would be necessary to consider them simultaneously. Therefore, we expect that the proposed methods would largely extend the application area of intelligent projection systems except for severely arbitrary environment.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.700-705
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• 2007

프로젝션 기반의 증강현실(AR, augmented reality) 시스템이란, 고화질의 가상 정보를 프로젝터를 통하여 정해진 공간에 정확하게 표시해 주는 시스템을 말한다. 대부분의 증강현실 시스템은 사용자의 몰입감을 높이기 위해 고화질, 대 화면을 제공하기 위한 디스플레이 장치를 사용하며, 영상처리의 복잡도에 따른 고성능의 프로세스 장치를 요구하기 때문에 데스크탑 환경에서 이루어졌다. 그러나, 데스크탑 환경에서의 증강현실 시스템은 휴대가 불편하다는 단점을 가진다. 최근 프로젝터의 소형화와 모바일 프로세서의 성능 향상은 휴대가 편리한 모바일 증강현실 시스템의 등장을 가능하게 하였다. 그러나, 모바일 증강현실 시스템은 작은 디스플레이를 이용하여 영상 정보를 표시해 주기 때문에 높은 해상도를 지원할 수 없으며, 사용자의 몰입감을 감소시킨다는 단점을 가지고 있다. 본 논문에서는 기존의 증강현실 시스템의 단점을 보완하기 위하여 PDA와 소형 프로젝터를 결합하여 프로젝션 기반의 휴대용 멀티미디어 플레이어($PMP^2$ : Portable Multimedia Player using Projection-Based augmented reality)라는 모바일 증강현실 시스템을 제안한다. $PMP^2$는 모바일 프로세서의 대표격이라 할 수 있는 PDA와 휴대용 소형 프로젝터를 이용함으로써 고화질, 대화면의 증강현실 영상을 다수의 사용자가 원하는 장소와 시간에 즐길 수 있도록 해 준다. $PMP^2$는 스크린의 기하 및 컬러에 따른 왜곡을 보상해 줌으로써, 특정한 스크린 없이도 언제 어디서나 사용자에게 정확한 영상을 제공해 준다. 본 논문에서는 다양한 시나리오에 대해 $PMP^2$의 유용성을 검증함으로써 모바일 환경에서의 프로젝션 기반의 증강 현실 시스템의 활용 가능성을 제시한다.

• Journal of the Korea Computer Graphics Society
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• v.13 no.2
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• pp.55-60
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• 2007

Diminished reality (DR) is a technique that provide a visual convenience by virtually hiding an object. Most of existing DR systems have been implemented based on HMDs or desktop displays. However, Here has been no report on the development of DR system based on projection displays due to technical difficulty in spite of its superiority in the aspect of human factor to conventional displays. Rapid advances of projection displays and projection-based vision technologies motivated us to develop a projection-based DR system. As the first attempt, this paper proposes a projection-based diminished reality system using an image completion technique. Its usefulness is demonstrated through experiments and its potential applications are discussed.

• Journal of the Korea Computer Graphics Society
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• v.21 no.3
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• pp.1-10
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• 2015

One way to create a visually immersive environment is to utilize a front projection system. Especially, when enough space is not available behind the screen, it becomes difficult to install a back projection system, making the front projection an appropriate choice. A drawback associated with the front projection is, however, the interference of shadow. The shadow can be cast on the screen when the user is located between the screen and the projector. This shadow can negatively affect the user experience and reduce the sense of immersion by removing important information. There have been various attempts to eliminating shadows cast on the screen by using multiple projectors that compensate for each other with missing information. There is trade-off between calculataion time and desired accuracy in this mutual compensation. Accurate estimation of the shadow usually requires heavy computation while simple approaches suffer from inclusion of non-shadow regions in the result. We propose a novel approach to removing shadows created in the front projection system using the skeleton data obtained from a depth camera. The skeleton data helps accurately extract the shape of the shadow that the user cast without requiring much computation. Our method also utilizes a distance field to remove the afterimage of shadow that may occur when the user moves. We verify the effectiveness of our system by performing various experiments in an interactive environment created by a front projection system.

• Journal of Broadcast Engineering
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• v.17 no.6
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• pp.945-953
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• 2012

A depth map can be obtained by projecting/capturing patterns of stripes using a projector-camera system and analyzing the geometric relationship between the projected patterns and the captured patterns. This is usually called structured light technique. In this paper, we propose a new multi-threading scheme for accelerating a conventional structured light technique. On CPUs and GPUs, multi-threading can be implemented by using OpenMP and CUDA, respectively. However, the problem is that their performance changes according to the computational conditions of partial processes of a structured light technique. In other words, OpenMP (using multiple CPUs) outperformed CUDA (using multiple GPUs) in partial processes such as pattern decoding and depth estimation. In contrast, CUDA outperformed OpenMP in partial processes such as rectification and pattern segmentation. Therefore, we carefully analyze the computational conditions where each outperforms the other and do use the better one in the related conditions. As a result, the proposed method can estimate a depth map in a speed of over 25 fps on $1280{\times}800$ images.