• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.256-259
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• 2003

This paper proposes OPTICAL MARKER fer registering process - one of the 3D measurement process : scan registering - merging - measurement. If the registering work is carried out manually, it can be accompanied with much time and many errors. Because the patterned marker make registering process automatic, many firms use it now. But the physical shape of existing markers is the source of the data loss caused by hiding surface, and the marker arrangement is the source of the time loss. The optical marker proposed in this paper has marker generator, organized a large number of binary coded control laser diode, separate from 3D scan object. So, it does not take much time for the marker disposition, and it is not the origin of the data loss, and the binary coded laser information make the auto-registering possible.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.558-561
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• 2009

In this paper, we propose Simple Frame Marker(SFMarker) to support recognition of characters and images included in a marker in augmented reality. If characters are inserted inside of marker and are recognised using Optical Character Recognition(OCR), it doesn't need marker learning process before an execution. It also reduces visual disturbance compared to 2D barcode marker due to familarity of characters. Therefore, proposed SFMarker distinguishes Square SFMarker that embeds images from Rectangle SFMarker with characters according to ratio of marker and applies different recognition algorithms. Also, in order to reduce preprocessing of character recognition, SFMarker inserts direction information in border of marker and extracts it to execute character recognition fast and correctly. Finally, since the character recognition for every frame slows down tracking speed, we increase the speed of recognition process using the result of character recognition in previous frame when frame difference is low.

• The Optical Journal
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• s.123
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• pp.57-57
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• 2009

• KIPS Transactions on Software and Data Engineering
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• v.7 no.3
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• pp.107-112
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• 2018

In this paper, optical flow based keypoint detection and tracking technique is proposed for the collaboration between flying drone with vision system and ground robots. There are many challenging problems in target detection research using moving vision system, so we combined the improved FAST algorithm and Lucas-Kanade method for adopting the better techniques in each feature detection and optical flow motion tracking, which results in 40% higher in processing speed than previous works. Also, proposed image binarization method which is appropriate for the given marker helped to improve the marker detection accuracy. We also studied how to optimize the embedded system which is operating complex computations for intelligent functions in a very limited resources while maintaining the drone's present weight and moving speed. In a future works, we are aiming to develop collaborating smarter robots by using the techniques of learning and recognizing targets even in a complex background.

• Journal of Korea Multimedia Society
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• v.21 no.10
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• pp.1162-1170
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• 2018

This paper presents an augmented reality system for multiple users. The proposed system performs ar image-based pose estimation of users and pose of each user is shared with other uses via a network server. For camera-based pose estimation, we install multiple markers in a pre-determined space and select the marker with the best appearance. The marker is detected by corner point detection and for robust pose estimation. the marker's corner points are tracked by optical flow tracking algorithm. Experimental results show that the proposed system successfully provides an augmented reality application to multiple users even when users are rapidly moving and some of markers are occluded by users.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.69-72
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• 2011

In this paper, we propose a method to track the movement of camera from the video sequences. This method is useful for video analysis and can be applied as pre-processing step in some application such as video stabilizer and marker-less augmented reality. First, we extract the features in each frame using corner point detection. The features in current frame are then compared with the features in the adjacent frames to calculate the optical flow which represents the relative movement of the camera. The optical flow is then analyzed to obtain camera movement parameter. The final step is camera movement estimation and correction to increase the accuracy. The method performance is verified by generating a 3D map of camera movement and embedding 3D object to the video. The demonstrated examples in this paper show that this method has a high accuracy and rarely produce any jitter.

• Current Optics and Photonics
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• v.8 no.1
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• pp.72-79
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• 2024

Recent flat-panel displays have become increasingly complicated to facilitate multiple display functions. In particular, the form of multilayered architectures for next-generation displays makes precise three-dimensional alignment of multiple panels a challenge. In this paper, a diffractive optical alignment marker is proposed to address the problem of three-dimensional alignment of distant dual panels beyond the depth-of-focus of a vision camera. The diffractive marker is effective to analyze the positional correlation of distant dual panels. The possibility of diffractive alignment in multilayer display fabrication is testified with numerical simulation and a proof-of-concept experiment.

• Journal of Korea Game Society
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• v.10 no.5
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• pp.103-113
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• 2010

In this paper, we present a practical method for generating facial animation by using an optical motion capture system. In our setup, we assumed a situation of capturing the body motion and the facial expression simultaneously, which degrades the quality of the captured marker data. To overcome this problem, we provide an integrated framework based on the local coordinate system of each marker for labeling the marker data, hole-filling and removing noises. We justify the method by applying it to generate a short animated film.

• Journal of Sensor Science and Technology
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• v.26 no.6
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• pp.371-378
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• 2017

An accurate and robust estimation of center of rotation (CoR) using optical marker trajectory is crucial in human biomechanics. In this regard, the performances of the two prevailing least-squares methods, the Gamage and Lasenby (GL) method, and the Chang and Pollard (CP) method, are verified in this paper. While both methods are sphere-fitting approaches in closed form and require no tuning parameters, they have not been thoroughly verified by comparison of their estimation accuracies. Furthermore, while for both methods, results for stationary CoR locations are presented, cases for perturbed CoR locations have not been investigated for any of them. In this paper, the estimation performances of the GL method and CP method are investigated by varying the range of motion (RoM) and noise amount, for both stationary and perturbed CoR locations. The difference in the estimation performance according to the variation in the amount of noise and RoM was clearly shown for both methods. However, the CP method outperformed the GL method, as seen in results from both the simulated and the experimental data. Particularly, when the RoM is small, the GL method failed to estimate the appropriate CoR while the CP method reasonably maintained the accuracy. In addition, the CP method showed a considerably better predictability in CoR estimation for the perturbed CoR location data than the GL method. Accordingly, it may be concluded that the CP method is more suitable than the GL method for CoR estimation when RoM is limited and CoR location is perturbed.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.11
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• pp.1074-1080
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• 2006

Motion capture systems are gaining popularity in entertainment, medicine, sports, education, and industry, with animation and gaming applications for entertainment taking the lead. A wide variety of systems are available for motion capture, but most of them are complicated and expensive. In the general class of optical motion capture, two or more optical sensors are needed to measure the 3D positions of the markers attached to the body. Recently, a 3D motion capture system using two Position Sensitive Detector (PSD) optical sensors was introduced to capture high-speed motion of an active infrared LED marker. The PSD-based system, however, is limited by a geometric calibration procedure for two PSD sensor modules that is too difficult for common customers. In this research, we have introduced a new system that used a single PSD sensor unit to obtain 3D positions of active IR LED-based markers. This new system is easy to calibrate and inexpensive.