• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권6호
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• pp.2689-2708
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• 2016

Multi-camera systems which integrate two or more low-cost digital cameras are adopted to reach higher ground coverage and improve the base-height ratio in low altitude remote sensing. To guarantee accurate multi-camera integration, the geometric relationship among cameras must be determined through platform calibration techniques. This paper proposed a combined two-step platform calibration method. In the first step, the static platform calibration was conducted based on the stable relative orientation constraint and convergent conditions among cameras in static environments. In the second step, a dynamic platform self-calibration approach was proposed based on not only tie points but also straight lines in order to correct the small change of the relative relationship among cameras during dynamic flight. Experiments based on the proposed two-step platform calibration method were carried out with terrestrial and aerial images from a multi-camera system combined with four consumer-grade digital cameras onboard an unmanned aerial vehicle. The experimental results have shown that the proposed platform calibration approach is able to compensate the varied relative relationship during flight, acquiring the mosaicing accuracy of virtual images smaller than 0.5pixel. The proposed approach can be extended for calibrating other low-cost multi-camera system without rigorously mechanical structure.

• 한국정보통신학회논문지
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• 제25권4호
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• pp.615-618
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• 2021

Recently, 3D reconstruction of real objects with multi-cameras has been widely used for many services such as VR/AR, motion capture, and plenoptic video generation. For accurate 3D reconstruction, geometry and color matching between multiple cameras will be needed. However, previous calibration and correction methods for geometry (internal and external parameters) and color (intensity) correction is difficult for non-majors to perform manually. In this paper, we propose a toolkit with procedural geometry calibration and color correction among cameras with different positions and types. Our toolkit consists of an easy user interface and turned out to be effective in setting up multi-cameras for reconstruction.

• 한국측량학회지
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• 제28권3호
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• pp.369-375
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• 2010

다각사진은 3차원 공간정보의 시각화 뿐 아니라 측정 목적으로도 사용되므로 카메라 시스템에 대한 캘리브레이션이 요구된다. 다각사진 카메라 시스템을 구성하는 각 카메라는 홀더에 장착되어 상대적인 자세 및 위치가 고정된다. 따라서 투영중심점 위치와 자세각은 중앙에 장착된 연직사진에 대해서 적용하고 나머지 4 대의 경사사진용 카메라에 대한 투영중심점 위치 및 자세각은 연직사진에 대한 상대적인 값으로부터 계산될 수 있다. 이에 본 연구에서는 다각사진 카메라 시스템에 의해 실제 촬영된 다각사진을 이용하여 항공삼각측량을 실시 한 후 얻어진 다각사진의 외부표정요소로부터 연직사진을 기준으로 경사사진의 상대적 자세각과 투영중심점의 상대적 위치에 대해 조사 분석하였다. 연구결과 연직사진에 대한 경사사진의 투영중심점 위치는 표준편차가 크게 나타났으며 자세각에 대해서는 경사방향에 관계없이 연직사진을 고정하고 경사사진만 조정할 때 그 표준편차가 더 작게 나타났다. 또한 전체 외부표정요소를 구할 경우보다 자세각만 구할 경우 전반적으로 표준편차가 작으며 안정적인 것을 알 수 있었다.

• ETRI Journal
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• 제29권4호
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• pp.411-420
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• 2007

The steady evolution of mapping technology is leading to an increasing availability of multi-sensory geo-spatial datasets, such as data acquired by single-head frame cameras, multi-head frame cameras, line cameras, and light detection and ranging systems, at a reasonable cost. The complementary nature of the data collected by these systems makes their integration to obtain a complete description of the object space. However, such integration is only possible after accurate co-registration of the collected data to a common reference frame. The registration can be carried out reliably through a triangulation procedure which considers the characteristics of the involved data. This paper introduces algorithms for a multi-primitive and multi-sensory triangulation environment, which is geared towards taking advantage of the complementary characteristics of spatial data available from the above mentioned sensors. The triangulation procedure ensures the alignment of involved data to a common reference frame. The devised methodologies are tested and proven efficient through experiments using real multi-sensory data.

• 방송공학회논문지
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• 제24권4호
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• pp.573-579
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• 2019

완전한 자율 주행에 이르기 위해서는 주변 환경을 인지하는 인지 능력이 사람보다 뛰어나야 한다. 자율 주행에서 주로 사용되는 $60^{\circ}$ 협각, $120^{\circ}$ 광각 카메라는 시야각에 따른 각각의 단점이 존재한다. 본 논문의 목적은 광각, 협각 카메라가 가진 각각의 단점을 극복하기 위하여, 다중화각 차량 전방 카메라 시스템을 이용하여 더 넓은 영역의 전방을 대상으로 더 정확히 객체를 인식할 수 있는 심층신경망 알고리즘을 개발하는 것이다. 광각, 협각 카메라로 취득된 데이터의 종횡비를 분석해 SSD(Single Shot Detector) 알고리즘을 수정하였고, 취득된 데이터를 학습하여 단안 카메라만을 사용할 때 보다 높은 성능을 달성하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 추계학술대회
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• pp.422-424
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• 2021

In this paper, it leads the approach of fusing multiple RGB cameras for visual objects recognition based on deep learning with convolution neural network and 3D Light Detection and Ranging (LiDAR) to observe the environment and match into a 3D world in estimating the distance and position in a form of point cloud map. The goal of perception in multiple cameras are to extract the crucial static and dynamic objects around the autonomous vehicle, especially the blind spot which assists the AV to navigate according to the goal. Numerous cameras with object detection might tend slow-going the computer process in real-time. The computer vision convolution neural network algorithm to use for eradicating this problem use must suitable also to the capacity of the hardware. The localization of classified detected objects comes from the bases of a 3D point cloud environment. But first, the LiDAR point cloud data undergo parsing, and the used algorithm is based on the 3D Euclidean clustering method which gives an accurate on localizing the objects. We evaluated the method using our dataset that comes from VLP-16 and multiple cameras and the results show the completion of the method and multi-sensor fusion strategy.

• International Journal of Fluid Machinery and Systems
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• 제3권2호
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• pp.122-128
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• 2010

The attachment of inducer in front of main impeller is a powerful method to improve cavitation performance; however, cavitation surge oscillation with low frequency occurs with blade cavity growing to each throat section of blade passage simultaneously. Then, one conceptual method of installing suction axi-asymmetrical plate has been proposed so as to keep every throat passage away from being unstable at once, and the effect on suppression of the oscillation were investigated. In the present study, cavitation behaviors in the inducer is observed with distributing multi-cameras circumferentially, recording simultaneously and reconstructing multi-photos on one plane field as moving a linear cascade. Observed results are utilized for discussion with other measuring results as casing wall pressure distribution. Then the suppression mechanism of oscillation by installing axi-asymmetrical inlet plate will be clarified in more details.

• 방송공학회논문지
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• 제18권3호
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• pp.463-473
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• 2013

본 논문에서는 다시점 영상을 이용한 초고해상도 영상 복원 기법을 제안한다. 구체적으로 $5{\times}5$ 배열로 구성된 다시점 카메라로 25장의 영상을 취득하고, 가운데 카메라에 해당하는 초고해상도 영상을 저해상도 입력 영상과 24장의 저해상도 참조 영상을 활용하여 생성한다. 우선 입력 영상을 중심으로 스테레오 정합 기법을 이용하여 24개의 참조 영상에 대한 변이지도를 각각 추정한다. 그리고 저해상도 영상과 참조 영상에 있는 일치점들을 이용하여 초고해상도 영상을 복원한다. 최종적으로 반복적 균일화를 통해 초고해상도 영상을 보정한다. 실험을 통하여 본 논문에서 제안한 초고해상도 영상 복원 기법의 성능이 우수함을 확인한다.

• 한국측량학회지
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• 제32권3호
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• pp.191-204
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• 2014

In recent years, multi-camera systems have been recognized as an affordable alternative for the collection of 3D spatial data from physical surfaces. The collected data can be applied for different mapping(e.g., mobile mapping and mapping inaccessible locations)or metrology applications (e.g., industrial, biomedical, and architectural). In order to fully exploit the potential accuracy of these systems and ensure successful manipulation of the involved cameras, a careful system calibration should be performed prior to the data collection procedure. The calibration of a multi-camera system is accomplished when the individual cameras are calibrated and the geometric relationships among the different system components are defined. In this paper, a new single-step approach is introduced for the calibration of a multi-camera system (i.e., individual camera calibration and estimation of the lever-arm and boresight angles among the system components). In this approach, one of the cameras is set as the reference camera and the system mounting parameters are defined relative to that reference camera. The proposed approach is easy to implement and computationally efficient. The major advantage of this method, when compared to available multi-camera system calibration approaches, is the flexibility of being applied for either directly or indirectly geo-referenced multi-camera systems. The feasibility of the proposed approach is verified through experimental results using real data collected by a newly-developed indirectly geo-referenced multi-camera system.

• Journal of Information Processing Systems
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• 제15권4호
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• pp.785-796
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• 2019

Due to the view point, illumination, personal gait and other background situation, person re-identification across cameras has been a challenging task in video surveillance area. In order to address the problem, a novel method called Joint Bayesian across different cameras for person re-identification (JBR) is proposed. Motivated by the superior measurement ability of Joint Bayesian, a set of Joint Bayesian matrices is obtained by learning with different camera pairs. With the global Joint Bayesian matrix, the proposed method combines the characteristics of multi-camera shooting and person re-identification. Then this method can improve the calculation precision of the similarity between two individuals by learning the transition between two cameras. For investigating the proposed method, it is implemented on two compare large-scale re-ID datasets, the Market-1501 and DukeMTMC-reID. The RANK-1 accuracy significantly increases about 3% and 4%, and the maximum a posterior (MAP) improves about 1% and 4%, respectively.