• International Journal of Aeronautical and Space Sciences
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• 제16권3호
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• pp.380-393
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• 2015

This study presents how we can evaluate stereo camera systems for the structural deformation monitoring. A stereo camera system, consisting of a set of stereo cameras and reflective markers attached on the structure, is introduced for the measurement and the stereo pattern recognition (SPR) method is utilized for the full-field structural deformation estimation. Performance of this measurement system depends on many parameters including types and specifications of the cameras, locations and orientations of them, and sizes and positions of markers; it is difficult to experimentally identify the effects of each parameter on the measurement performance. In this study, a simulation framework for evaluating performance of the stereo camera systems with various parameters has been developed. The maximum normalized root-mean-square (RMS) error is defined as a representative index of stereo camera system performance. A plate structure is chosen for an introductory example. Its several modal harmonic vibrations are generated and estimated in the simulation framework. Two cases of simulations are conducted to see the effects of camera locations and the resolutions of the cameras. An experimental validation is carried out for a few selected cases from the simulations. Using the simultaneous laser displacement sensor (LDS) measurements as the reference, the measurement errors are obtained and compared with the simulations.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.396-399
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• 2009

스테레오 비전 시스템(stereo vision system)은 2차원 영상정보를 이용하여 3차원 깊이 정보를 획득하는 데 유용한 방법으로, 그동안 많은 연구가 진행되었다. 3차원 깊이 정보를 획득하기 위해서는 영상의 대응점을 찾아야 하는데, 속도와 정확성을 동시에 만족시키기가 어렵다. 이러한 문제를 해결하기 위해, 본 논문에서는 적응적 가중치(weight)를 적용한 cost aggregation 기반의 스테레오 정합 기법을 제안한다. 이 방법은 스테레오 영상의 특징을 이용하여 가중치를 획득하고, 색상정보, 밝기정보, 거리정보에 가중치를 적용한 후, 이를 이용하여 대응점을 찾아 깊이 정보를 추출한다. 제안된 방법의 성능을 평가하기 위하여 ground truth가 존재하는 다양한 스테레오 영상을 이용하여 실험하였으며, 실험 결과 다양한 영상에서도 향상된 결과를 보였다.

• 제어로봇시스템학회지
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• 제2권6호
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• pp.21-29
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• 1996

본 논문의 구성은 2장에서는 밝기 분포로부터의 형상복구(Shape from shading)의 한 방법인 고전적인 Photometric stereo mehtod에 대해서 개략적으로 고찰해 보고 3장, 4장에서는 혼성반사모델(Hybrid reflectance model)을 기반으로 하는 2종류의 확장된 Photometric stereo 방법에 대해 설명하고, 각 경우에 대한 시뮬레이션 결과를 2.5차원 및 3차원 형상으로 보이고 고찰한다. 5장에서는 결론 및 고찰에 대해서 언급하고 논문을 마친다.

• Journal of Information Display
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• 제6권4호
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• pp.26-34
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• 2005

In this paper, a new rectification scheme to transform the uncalibrated stereo image pair into the calibrated one is suggested and its performance is analyzed by applying this scheme to the reconstruction of the intermediate views for multi-view stereoscopic display. In the proposed method, feature points are extracted from the stereo image pair by detecting the comers and similarities between each pixel of the stereo image pair. These detected feature points, are then used to extract moving vectors between the stereo image pair and the epipolar line. Finally, the input stereo image pair is rectified by matching the extracted epipolar line between the stereo image pair in the horizontal direction. Based on some experiments done on the synthesis of the intermediate views by using the calibrated stereo image pairs through the proposed rectification algorithm and the uncalibrated ones for three kinds of stereo image pairs; 'Man', 'Face' and 'Car', it is found that PSNRs of the intermediate views reconstructed from the calibrated images improved by about 2.5${\sim}$3.26 dB than those of the uncalibrated ones.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.100.2-100
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• 2002

In this paper we propose a new visual servoing method for door opening with mobile manipulator. We use an eye-to-hand system that stereo camera is mounted on mobile platform, and adopt the position-based method. The previous methods for door opening mostly used eye-in-hand system with mono camera and required predefined knowledge such as radius and position about door grip, which was mainly caused by using mono cam era. This is also a severe constraint for pursuing general-purpose algorithm for door opening. For overcoming such drawback, we use stereo camera and suggest a new method that detect the door grip and estimate its pose from stereo depth information without predefined knowledge. Al...

• 대한전기학회논문지:시스템및제어부문D
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• 제52권3호
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• pp.163-172
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• 2003

A stereo matching has been an important tool for the reconstruction of 3D terrain. The current state of stereo matching technology has reached the level where a very elaborate DEM(Digital Elevation Map) can be obtained. However, there still exist many factors causing DEM error in stereo matching. This paper propose a new method to reduce the error caused by the lack of significant features in the correlation window The proposed algorithm keeps the correlation window as small as possible, as long as there is a significant feature in the window. Experimental results indicate that the proposed method increases the DEM accuracy by $72.65\%$ in the plain area and $41.96\%$ in the mountain area over the conventional scheme. Comparisons with Kanade's result show that the proposed method eliminates spike type of errors more efficiently than Kanade's adaptive window technique and produces reliable DEM.

• International journal of advanced smart convergence
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• 제7권3호
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• pp.8-14
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• 2018

In the field of surveillance cameras, it is possible to increase the people detection accuracy by using depth information indicating the distance between the camera and the object. In general, depth information is obtained by calculating the parallax information of the stereo camera. However, this method is difficult to operate in real time in the embedded environment due to the large amount of computation. Jetson TX2, released by NVIDIA in March 2017, is a high-performance embedded board with a GPU that enables parallel processing using the GPU. In this paper, a stereo camera is installed in Jetson TX2 to acquire depth information in real time, and we proposed a people counting method using acquired depth information. Experimental results show that the proposed method had a counting accuracy of 98.6% and operating in real time.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.28.2-28
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• 2001

Three dimensional shape measurement techniques are widely needed in industries for product quality monitoring and control. X-ray imaging method is a promising technology to achieve three-dimensional Information, both the surface and inner structure of an object, since it can overcome the limitations of conventional visual or optical methods such as an occlusion problem or surface reflection properties. In this paper, we propose three dimensional volume reconstruction method based on x-ray stereo imaging technology. Here, the stereo images of an object from two different views are taken by changing the object pose rather than moving imaging plane as in conventional stereo vision method. We propose a series of image processing techniques to extract the features efficiently from x-ray images, where the occluded features in case of normal camera vision could be found ...

• International Journal of Automotive Technology
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• 제8권4호
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• pp.493-504
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• 2007

This paper proposes a stereo vision-based forward obstacle detection and distance measurement method. In general, stereo vision-based obstacle detection methods in automotive applications can be classified into two categories: IPM (Inverse Perspective Mapping)-based and disparity histogram-based. The existing disparity histogram-based method was developed for stop-and-go applications. The proposed method extends the scope of the disparity histogram-based method to highway applications by 1) replacing the fixed rectangular ROI (Region Of Interest) with the traveling lane-based ROI, and 2) replacing the peak detection with a constant threshold with peak detection using the threshold-line and peakness evaluation. In order to increase the true positive rate while decreasing the false positive rate, multiple candidate peaks were generated and then verified by the edge feature correlation method. By testing the proposed method with images captured on the highway, it was shown that the proposed method was able to overcome problems in previous implementations while being applied successfully to highway collision warning/avoidance conditions, In addition, comparisons with laser radar showed that vision sensors with a wider FOV (Field Of View) provided faster responses to cutting-in vehicles. Finally, we integrated the proposed method into a longitudinal collision avoidance system. Experimental results showed that activated braking by risk assessment using the state of the ego-vehicle and measuring the distance to upcoming obstacles could successfully prevent collisions.

• 방송공학회논문지
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• 제14권3호
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• pp.322-331
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• 2009

본 논문은 윤곽선 기반 메쉬 최적화를 이용한 스테레오 영상의 효율적인 데이터 표현 방법을 제안한다. 스테레오 영상에 대한 메쉬 기반 2차원 워핑은 주로 제어점 선택과 선택된 제어점들의 시차 정보 추정 성능에 의존한다. 따라서 제안된 방법은 제어점 선택을 위하여 강한 윤곽선과 객체의 경계선만으로 구성된 특징 지도를 생성하고 이를 기반으로 격자형 메쉬를 생성한다. 또한, 지역단위로 2차원 워핑을 수행하며 목적영상과의 오차를 최소로 하는 제어점의 위치를 반복적으로 추정하게 된다. 최적화된 제어점 위치를 찾기 위한 반복적 2차원 워핑 과정은 많은 계산 시간을 요구하기 때문에 이를 개선하기 위하여 입력된 스테레오 영상은 수평 시차만 존재하고 최적의 제어점 위치는 객체의 경계선을 포함한 윤곽선 위에 존재함을 가정한다. 따라서 제안한 윤곽선 기반 워핑 방법은 수평선 위에 윤곽선만을 따라 반복적으로 최적화된 제어점 위치를 탐색한다. 본 논문의 실험에서는 스테레오 영상에 대하여 제어점 수에 따른 신호에 대한 잡음비(PSNR)를 측정하여 기존 방법과 제안한 방법의 품질을 비교 하였다. 뿐만 아니라 최적의 메쉬 생성을 위한 수행시간을 비교하여 평가하였다. 실험 결과를 통하여 제안한 방법은 적은 수의 제어점을 이용하여 품질의 저하를 줄이고 빠르게 최적의 메쉬를 생성함으로써 효율적인 스테레오 영상 표현 방법을 제공하였다.