• Journal of the Optical Society of Korea
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• 제8권2호
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• pp.65-71
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• 2004

In this paper, we analyze the limitation on the expressible depth range that is one major problem of integral imaging. We provide the explanation that exactly predicts the experimental results and the way to evaluate the expressible depth range numerically. We also give the design method for the multi-central depth plane integral imaging system. Finally, we will show the experimental results for verification.

• 제어로봇시스템학회논문지
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• 제5권4호
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• pp.437-445
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• 1999

Most autonomous mobile robots view only things in front of then, and as a result, they may collide with objects moving from the side or behind. To overcome this problem, an active omni-directional range sensor system has been built that can obtain an omni-directional depth map through the use of a laser conic plane and a conic mirror. In the navigation of the mobile robot, the proposed sensor system produces a laser conic plane by rotating the laser point source at high speed: this creates a two-dimensional depth map, in real time, once an image is captured. The results obtained from experiment show that the proposed sensor system is very efficient, and can be utilized for navigation of mobile robot in an unknown environment.

• 한국음향학회지
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• 제38권3호
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• pp.302-307
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• 2019

현대 대잠전에 있어 잠수함에 대한 2차원 위치추정에 다양한 방법들이 있다. 잠수함에 대한 보다 효과적인 추적 및 공격을 위해 표적 심도는 매우 중요한 요소이다. 하지만 현재까지도 잠수함의 심도를 찾아낸다는 것은 어려운 일이다. 본 논문에서는 최단접근점(Closest Point of Approach, CPA) 전후의 표적 접촉방위와 표적 도플러 신호 등 다이파 소노부이 접촉정보를 이용한 잠수함 심도 추정 기법을 제안하고자 한다. 표적의 상대심도는 표적과 다이파 소노부이의 청음기 간 사선거리 및 수평거리에 피타고라스 정리를 적용하여 결정된다. 이때 사선거리는 도플러변이와 표적 속도에 의해서 계산되며, 수평거리는 표적에 대한 연속된 접촉방위와 표적의 이동거리에 삼각함수를 적용하여 얻을 수 있다. 본 논문에서 제시된 알고리즘의 성능은 소노부이-표적 간 수평거리 및 상대심도에 의해 결정되는 고각과 도플러 변이 값의 측정 정확성에 의해 좌우됨을 시뮬레이션을 통해 알 수 있다.

• Journal of Multimedia Information System
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• 제1권1호
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• pp.1-10
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• 2014

In this paper, we propose a new view synthesis technique for coding of multi-view color and depth data in arbitrary camera arrangements. We treat each camera position as a 3-D point in world coordinates and build clusters of those vertices. Color and depth data within a cluster are gathered into one camera position using a hierarchical representation based on the concept of layered depth image (LDI). Since one camera can cover only a limited viewing range, we set multiple reference cameras so that multiple LDIs are generated to cover the whole viewing range. Therefore, we can enhance the visual quality of the reconstructed views from multiple LDIs comparing with that from a single LDI. From experimental results, the proposed scheme shows better coding performance under arbitrary camera configurations in terms of PSNR and subjective visual quality.

• 센서학회지
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• 제33권2호
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• pp.98-104
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• 2024

This study proposes a method to overcome the limited detection range of short-baseline stereo cameras (SBSCs). The proposed method includes two steps: (1) predicting an unscaled initial depth using monocular depth estimation (MDE) and (2) adjusting the unscaled initial depth by a scale factor. The scale factor is computed by triangulating the sparse visual keypoints extracted from the left and right images of the SBSC. The proposed method allows the use of any pre-trained MDE model without the need for additional training or data collection, making it efficient even when considering the computational constraints of small platforms. Using an open dataset, the performance of the proposed method was demonstrated by comparing it with other conventional stereo-based depth estimation methods.

• Current Optics and Photonics
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• 제5권5호
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• pp.514-523
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• 2021

Methods for absolute depth estimation have received lots of interest, and most algorithms are concerned about how to minimize the difference between an input defocused image and an estimated defocused image. These approaches may increase the complexity of the algorithms to calculate the defocused image from the estimation of the focused image. In this paper, we present a new method to recover depth of scene based on a sharpness-assessment algorithm. The proposed algorithm estimates the depth of scene by calculating the sharpness of deconvolved images with a specific point-spread function (PSF). While most depth estimation studies evaluate depth of the scene only behind a focal plane, the proposed method evaluates a broad depth range both nearer and farther than the focal plane. This is accomplished using an asymmetric aperture, so the PSF at a position nearer than the focal plane is different from that at a position farther than the focal plane. From the image taken with a focal plane of 160 cm, the depth of object over the broad range from 60 to 350 cm is estimated at 10 cm resolution. With an asymmetric aperture, we demonstrate the feasibility of the sharpness-assessment algorithm to recover absolute depth of scene from a single defocused image.

• 한국재료학회지
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• 제13권9호
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• pp.606-612
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• 2003

Surface and mechanical properties of thin films with submicron thickness was characterized by nanoindentation with Berkovich and Vickers tips, and scanning probe microscopy. Nanoindention was made in a depth range of 15 to 200 nm from the surface by applying tiny force in a range from 150 to $9,000 \mu$N. Stiffness, contact area, hardness, and elastic modulus were determined from the force-displacement curve obtained. Reliability was first tested by using fused quartz, a standard sample. Elastic modulus and hardness values of fused quartz measured were the same as those reported in the literature within two percent of error. Mechanical properties of ITO thin film were characterized in a depth range of 15∼200nm. As indentation depth increased, elastic modulus and hardness decreased by substrate effect. Ion beam deposited DLC thin films were indented in a depth range of 40∼50 nm. The results showed that the DLC thin film using benzene and bias voltage 0∼-50 V has elastic modulus and hardness value of 132 and 18 GPa respectively. Pure DLC thin films showed roughnesses lower than 0.25 nm, but silicon-added DLC thin films showed much higher roughness values, and the wavy surface morphology.

• 한국측량학회지
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• 제23권2호
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• pp.197-203
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• 2005

연안에서의 준설, 매립, 항만건설 등의 공사 시 해상에서의 측량 조건에 따른 수심측량의 효율성과 정밀도에 대한 관심이 매우 높아지고 있다. 그러나 측량조건에 따른 수심측량의 정밀도 향상에 대한 연구는 부족한 실정이다. 수심측량의 정밀도 저하 요인 중 본 연구에서는 탁도 증가에 따른 echo sounder의 측심 특성 파악과 한계 탁도 구간을 제시하고자 하였다. 이를 위해, 인공수조에 탁도 유발물질을 인위적으로 투입하여 탁도 별 수심측정 값을 취득한 후, 회귀분석을 수행하여 탁도 증가에 따른 측심 특성이 정상관측구간, 한계구간, 관측불가능구간의 순으로 이루어지고 탁도에 대한 echo sounder 수심관측 한계구간이 $217\~259NTU$로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회 2차
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• pp.152-160
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• 2010

In this study, cohesion of soft ground, soft ground depth and embankment height varying conditions, such as the impact of each condition after the calculation of the range, SCP was performed to evaluate the applicability of the method. Reinforcing effects of scope, and permit lateral movement of SCP 2D and 3D analysis of the program were calculated by the displacement ratio, the result follows. The height and depth of soft soil embankment with increasing and decreasing the cohesion tends to be affected were long range, SCP method applied by the finite element analysis Cu = 1.0tf/$m^2$, embankment height is 3.0m depth of soft soil can be applied in a less than 5.0m, and Cu = 3.0tf/$m^2$, embankment height, the soft soil depth is 3.0m 12.0m, Cu = 3.0tf/$m^2$, embankment height is 5.0m less than 7.0m depth of soft soil can be applied in was. And Cu = 5.0tf/$m^2$, embankment height is 3.0m below 15.0m depth rouge anti Floor, Cu = 3.0tf/$m^2$, embankment height of 5.0m 12.0m depth below the soft soil, Cu = 5.0tf/$m^2$, If the depth of soft soil embankment height of 7.0m and below 5.0m was applicable.

• 한국산학기술학회논문지
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• 제13권8호
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• pp.3666-3671
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• 2012

적외선 거리 센서를 사용하여 취득한 깊이이미지(depth image)에 대하여 잘 알려진 얼굴인식 알고리즘을 수행하여 깊이이미지 응용에 적용가능성을 평가한다. 아울러, 기존의 얼굴인식이 정확도 측면에서만 강조를 해온 측면이 있는데 이렇게 하면 실제 환경에서 적용할 때 문제점을 제대로 평가하기 어렵다. 본 연구에서는 RGB 이미지와 깊이 이미지들에 대해 잘 알려진 얼굴 인식 알고리즘 (PCA, LDA, ICA, SVM)을 적용하여 얼굴인식 정확도뿐만 아니라 처리 속도, 사용 메모리 그리고 저장 공간에 대한 정보를 구해 이미지 유형과 각 알고리즘에 따른 전반적인 성능을 구하였다. 처리 결과 깊이이미지와 컬러 색인된 깊이이미지는 컬러이미지에 비해 각각 30% ~ 40% 정도 파일 크기가 작음에도 전반적인 성능에서 컬러이미지와 마찬가지로 우수한 결과를 보였으며, LDA는 SVM 다음으로 정확도도 우수하고 훈련시간과 훈련 소요메모리도 양호하고 테스트시간과 테스트 소요 메모리도 낮아 우수한 성능을 보였다.