• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.302-305
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• 2012

평면 추적(planar tracking) 기반의 카메라 추적에 있어, 특징 검출자의 반복성과 특징 기술자(descriptor)의 정합 성능에 따라서 떨림 현상(jitter)이 발생한다. 특히, 모바일 환경에서와 같은 연산력이 부족한 환경에서 고속화를 위해 특징 검출 및 기술 알고리즘을 간략화 시킬 경우, 이러한 떨림 현상은 심각한 문제가 된다. 본 논문에서는 이러한 문제를 해결하기 위해 입력 영상을 워핑(warping)하여 특징 점을 재검출한 후 카메라 영상과 참조 영상(reference image) 사이의 호모그래피를 보완하는 방법을 제안한다. 실험을 통해 제안된 방법이 특징 검출 및 기술 알고리즘의 성능을 보완하여 떨림 현상을 크게(70% 이상) 감소시킴을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.180-182
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• 2021

본 논문에서는 드론의 비행 장소와 온도 및 습도에 영향을 받지 않는 적외선 기반 깊이 카메라로부터 얻어진 깊이영상을 분석하여 지면 영역을 찾고 AGL(Above Ground Level) 단위의 고도를 측정하는 방법을 제안한다. Decimation filter 와 Median filter 를 적용하여 잡음 및 빈 데이터들을 제거한 깊이영상으로부터 RANSAC (RANdom Sample Consensus) 기반 평면 모델 추정 방법을 이용하여 지면 영역과 이에 대한 평면의 방정식을 유추하고 현재 위치와의 거리를 계산한다. 성능 평가를 위해 Lidar 센서와 비교한 결과, 제안 방법이 지면에 위치한 장애물에 영향을 더 적게 받으며, 자세 정보와 독립적으로 고도를 측정할 수 있었다.

• The Journal of the Korea Contents Association
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• v.11 no.5
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• pp.41-49
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• 2011

Recently, the infrastructure of stereoscopy is growing fast. Though, the stereoscopy producing capacity is insufficient to meet the demand of the market. Because, at the moment most people who produce the stereoscopy are skilled for the two-dimensional images. So the characteristics of the human stereopsis and stereoscopic cameras are not well considered, it occurs many problems to the viewer. According to this, we studied about the optical axis distance adjustment of stereoscopic camera considering size perception in human stereopsis. First, we measured the area of the object in the image which depends on the optical axis distance. Second, based on the output of first experiment, we conducted a survey and figured out that if we keep the optical axis distance between 3.9cm to 130cm, it wouldn't occur any size perception and will be possible to produce high quality stereoscopy.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.916-926
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• 2011

It is well known that high-resolution 3D movie contents frequently do not deliver the identical 3D perception to low-resolution 3D images. For solving this problem, we propose a novel method that produces a new stereoscopic image based on depth map transformation using the spatial complexity of an image. After analyzing the depth map histogram, the depth map is decomposed into multiple depth planes that are transformed based upon the spatial complexity. The transformed depth planes are composited into a new depth map. Experimental results demonstrate that the lower the spatial complexity is, the higher the perceived video quality and depth perception are. As well, visual fatigue test showed that the stereoscopic images deliver less visual fatigue.

• The Journal of the Korea Contents Association
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• v.14 no.10
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• pp.1-9
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• 2014

Generally, integral image used for autostereoscopic 3d display is generated for flat lens array, but flat lens array cannot provide a wide range of view for generated integral image because of narrow range of view. To make up for this flat lens array's weak point, curved lens array has been proposed, and due to technical and cost problem, approximate surface lens array composed of several flat lens array is used instead of ideal curved lens array. In this paper, we constructed an approximate surface lens array arranged for $20{\times}8$ square flat lens in 100mm radius sphere, and we could get about twice angle of view compared to flat lens array. Specially, unlike existing researches which manually generate integral image, we propose an OpenCL GPU parallel process algorithm for generating real-time integral image. As a result, we could get 12-20 frame/sec speed about various 3D volume data from $15{\times}15$ approximate surface lens array.

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1304-1313
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• 2006

Biometric-based authentication can provide strong security guarantee about the identity of users. However, security of biometric data is particularly important as the compromise of the data will be permanent. In this paper, we propose a secure and efficient protocol to transmit fingerprint images from a fingerprint sensor to a client by exploiting characteristics of fingerprint images. Because the fingerprint sensor is computationally limited, however, such encryption algorithm may not be applied to the full fingerprint images in real-time. To reduce the computational workload on the resource-constrained sensor, we apply the encryption algorithm to a specific bitplane of each pixel of the fingerprint image. We use the LSB as specific bitplane instead of MSB used to encrypt general multimedia contents because simple attacks can reveal the fingerprint ridge information even from the MSB-based encryption. Based on the experimental results, our proposed algorithm can reduce the execution time of the full encryption by a factor of six and guarantee both the integrity and the confidentiality without any leakage of the ridge information.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.231-236
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• 2016

Currently, a traffic monitoring service using a surveillance camera is provided through internet. In general, if the user points a certain location on a map, then this service shows the real-time image of the camera where it is mounted. In this paper, we proposed the intuitive surveillance monitoring system which displays a real-time camera image on the map by warping with bird's-eye view and with the top of image as the north. In order to robustly estimate the road plane using camera image, we used the motion vectors which can be detected to changes in brightness. We applied a re-adjustment process to have the same directivity with a map and presented a user-friendly interface that can be displayed on the map. In the experiment, the proposed method was presented as the result of warping image that the user can easily perceive like a map.

• Journal of the Korean Society of Radiology
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• v.16 no.4
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• pp.365-371
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• 2022

In order to obtain excellent spatial resolution in the PET detector, when the detector module is designed using very small scintillation pixels, overlap occurs at the edges and corners of the scintillation pixel array in the flood image. By using a light guide, the occurrence of overlap can be reduced. In this study, after using a scintillator of 0.8 mm × 0.8 mm × 20 mm to form a 14 × 14 array, 3 mm × 3 mm SiPM pixels are combined with 4 × 4 photosensor to reduce the occurrence of overlap. The optimal thickness of the light guide used for this purpose was derived. Quantitative evaluation was performed based on scintillation pixel images of edges and corners where overlap occurs mainly in the acquired flood image. Quantitative evaluation was calculated through the interval and full width at half maximum between scintillation pixel images, and when a light guide with a thickness of 2 mm was used, the best image was obtained with a k value of 2.60. In addition, as a result of measuring the energy resolution through the energy spectrum, the light guide with a thickness of 2 mm showed the best result at 28.5%. If a 2 mm light guide is used, it is considered that the best flood image and energy resolution with minimal overlap can be obtained.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.973-985
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• 2019

In this paper, we propose a method to separate the ground and building areas and generate building models automatically through planarity analysis using UAV (Unmanned Aerial Vehicle) based point cloud. In this study, proposed method includes five steps. In the first step, the planes of the point cloud were extracted by analyzing the planarity of the input point cloud. In the second step, the extracted planes were analyzed to find a plane corresponding to the ground surface. Then, the points corresponding to the plane were removed from the point cloud. In the third step, we generate ortho-projected image from the point cloud ground surface removed. In the fourth step, the outline of each object was extracted from the ortho-projected image. Then, the non-building area was removed using the area, area / length ratio. Finally, the building's outer points were constructed using the building's ground height and the building's height. Then, 3D building models were created. In order to verify the proposed method, we used point clouds made using the UAV images. Through experiments, we confirmed that the 3D models of the building were generated automatically.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.991-996
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• 2007

Recently, a computational reconstruction method using an integral imaging technique, which is a promise three-dimensional display technique, has been actively researched. This method is that 3-D images can be digitally reconstructed at the required output planes by superposition of all of the inversely enlarged elemental images by using a hypothetical pinhole array model. However, the conventional method mostly yields reconstructed images having a low-resolution, because there are some intensity irregularities with a grid structure at the reconstructed mage plane by using square-type elemental images. In this paper, to overcome this problem, we propose a novel computational integral imaging reconstruction (CIIR) method using round-type mapping model. Proposed CIIR method can overcome problems of non-uniformly reconstructed images caused from the conventional method and improve the resolution of 3-D images. To show the usefulness of the proposed method, both computational experiment and optical experiment are carried out and their results are presented.