• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.3
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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.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.451-452
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• 2006

In this paper, we present a 3D reconstruction method using multi-camera. This method is very compact algorithm so that can be implemented easily on small hardware architecture. By using multi-camera, it gives exacter result than existing method and we propose accurate index for each matching nodes to use multi-camera.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.1-6
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• 2009

Due to the different camera properties of the multi-view camera system, the color properties of captured images can be inconsistent. This inconsistency makes post-processing such as depth estimation, view synthesis and compression difficult. In this paper, the method to correct the different color properties of multi-view images is proposed. We utilize a gray gradient bar on a display device to extract the color sensitivity property of the camera and calculate a look-up table based on the sensitivity property. The colors in the target image are converted by mapping technique referring to the look-up table. Proposed algorithm shows the good subjective results and reduces the mean absolute error among the color values of multi-view images by 72% on average in experimental results.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.50-53
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• 2003

본 논문에서는 multi-camera를 이용한 인터넷 기반의 지능적 감시 시스템을 제안한다. 제안된 시스템은 두 종류의 카메라, static camera와 pan-tilt camera, 를 이용하여 출입구를 감시하고, 비인가자를 추적한다. static camera는 출·입을 검출하고 출입자를 인가자와 비인가자로 분류하는데 이용되고, pan-tilt camera는 비인가자로 분류된 출입자를 추적하는데 이용된다. 제안된 시스템은 세 가지 단계: 출입구 감시, 출입자 검출 및 분류(인가자/비인가자), 비인가자 추적으로 구성된다 출입구 감시는 출입문의 밝기값 변화를 이용한다 출입자 검출 및 분류는 skin color 모델과 얼굴 크기, 위치와 관련된 휴리스틱을 이용하여 얼굴을 검출하고, PCA(Principal Component Analysis)를 이용한 eigenspace상에서의 유클리디언 디스턴스로 템플릿 얼굴과 입력 얼굴의 유사도를 계산하여 인가자인지 비인가자인지 분류한다. 비인가자 추적은 pan-tilt 카메라를 이용하여, static camera에서 분류된, 비인가자의 움직임을 검출하고 카메라를 제어함으로써 추적한다 제안된 시스템은 무인 감시 상황에서 비인가자의 출입시 감시자에게 경고 신호를 제공하고, 감시지역에서 사건 발생시, 사건의 개요를 파악하는 중요한 정보를 빠른 시간에 제공할 수 있다는 장점을 가진다.

• The Journal of Korea Robotics Society
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• v.17 no.3
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• pp.353-358
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• 2022

Due to the limited field of view of the pinhole camera, there is a lack of stability and accuracy in camera pose estimation applications such as visual SLAM. Nowadays, multiple-camera setups and large field of cameras are used to solve such issues. However, a multiple-camera system increases the computation complexity of the algorithm. Therefore, in multiple camera-assisted visual simultaneous localization and mapping (vSLAM) the multi-view tracking algorithm is proposed that can be used to balance the budget of the features in tracking and local mapping. The proposed algorithm is based on PanoSLAM architecture with a panoramic camera model. To avoid the scale issue 3D LiDAR is fused with omnidirectional camera setup. The depth is directly estimated from 3D LiDAR and the remaining features are triangulated from pose information. To validate the method, we collected a dataset from the outdoor environment and performed extensive experiments. The accuracy was measured by the absolute trajectory error which shows comparable robustness in various environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.6
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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.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.53-56
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• 2010

An aerial multi-looking camera system equips itself with five separate cameras which enables acquiring one vertical image and four oblique images at the same time. This provides diverse information about the site compared to aerial photographs vertically. However, multi-looking Aerial Camera for building a 3D spatial information don't use a large-size CCD camera, do uses a medium-size CCD camera, if acquiring forward, backward, left and right imagery of Certain objects, Aerial photographing set overlap and sidelap must be considered. Especially, Sideward-looking camera set up by the sidelap to determine whether a particular object can be acquisition Through our research we analyzed of sideward footprint and aerial photographing efficiency of Multi-view imagery by sidelap changing.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.4
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• pp.351-357
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• 2008

An aerial multi-looking camera system equips itself with five separate cameras which enables acquiring one vertical image and four oblique images at the same time. This provides diverse information about the site compared to aerial photographs vertically. The geometric relationship of oblique cameras and a vertical camera can be modelled by 6 exterior orientation parameters. Once the relationship between the vertical camera and each oblique camera is determined, the exterior orientation parameters of the oblique images can be calculated by the exterior orientation parameters of the vertical image. In order to examine the exterior orientation of both a vertical camera and each oblique cameras in the multi-looking camera relatively, calibration targets were installed in a lab and 14 images were taken from three image stations by tilting and rotating a non-metric digital camera. The interior orientation parameters of the camera and the exterior orientation parameters of the images were estimated. The exterior orientation parameters of the oblique image with respect to the vertical image were calculated relatively by the exterior orientation parameters of the images and error propagation of the orientation angles and the position of the projection center was examined.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.2
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• pp.146-152
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• 2011

Underwater CCTV camera systems are increasingly replaced the traditional net approach of assessing the species, numbers and aggregation patterns of marine animals distributing around the artificial reefs installed in the inshore fishing grounds, in particular, in relation to the biological investigation of behavior and distribution patterns of target fishes. In relation to these needs, we developed a multi-directional underwater CCTV camera system to use in detecting and tracking marine animals in the artificial reef ground. The marine targets to be investigated were independently tracked by using a camera module toward the bottom and four camera modules installed in the interval of $90^{\circ}$ in horizontal plane and inclination of $45^{\circ}$ in vertical plane of the CCTV system without the overlap of video frames by each camera module. From the results of several field tests at sea, we believe that the developed multi-directional underwater CCTV camera system will contribute to a better understanding in evaluating the effect of artificial reefs installed in the inshore fishing grounds.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.533-538
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• 2019

The mechanical-collimation imaging is the most mature technology in prompt gamma (PG) imaging which is considered the most promising technology for beam range verification in proton therapy. The purpose of the present study is to compare the performances of two mechanical-collimation PG cameras, knife-edge (KE) camera and multi-slit (MS) camera. For this, the PG cameras were modeled by Geant4 Monte Carlo code, and the performances of the cameras were compared for imaginary point and line sources and for proton beams incident on a cylindrical PMMA phantom. From the simulation results, the KE camera was found to show higher counting efficiency than the MS camera, being able to estimate the beam range even for $10^7$ protons. Our results, however, confirmed that in order to estimate the beam range correctly, the KE camera should be aligned, at least approximately, to the location of the proton beam range. The MS camera was found to show lower efficiency, being able to estimate the beam range correctly only when the number of the protons is at least $10^8$. For enough number of protons, however, the MS camera estimated the beam range correctly, errors being less than 1.2 mm, regardless of the location of the camera.