• 제목/요약/키워드: Optical flow algorithm

검색결과 189건 처리시간 0.027초

A method for image-based shadow interaction with virtual objects

  • Ha, Hyunwoo;Ko, Kwanghee
    • Journal of Computational Design and Engineering
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    • 제2권1호
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    • pp.26-37
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    • 2015
  • A lot of researchers have been investigating interactive portable projection systems such as a mini-projector. In addition, in exhibition halls and museums, there is a trend toward using interactive projection systems to make viewing more exciting and impressive. They can also be applied in the field of art, for example, in creating shadow plays. The key idea of the interactive portable projection systems is to recognize the user's gesture in real-time. In this paper, a vision-based shadow gesture recognition method is proposed for interactive projection systems. The gesture recognition method is based on the screen image obtained by a single web camera. The method separates only the shadow area by combining the binary image with an input image using a learning algorithm that isolates the background from the input image. The region of interest is recognized with labeling the shadow of separated regions, and then hand shadows are isolated using the defect, convex hull, and moment of each region. To distinguish hand gestures, Hu's invariant moment method is used. An optical flow algorithm is used for tracking the fingertip. Using this method, a few interactive applications are developed, which are presented in this paper.

Water Level Tracking System based on Morphology and Template Matching

  • Ansari, Israfil;Jeong, Yunju;Lee, Yeunghak;Shim, Jaechang
    • 한국멀티미디어학회논문지
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    • 제21권12호
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    • pp.1431-1438
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    • 2018
  • In this paper, we proposed a river water level detection and tracking of the river or dams based on image processing system. In past, most of the water level detection system used various water sensors. Those water sensors works perfectly but have many drawbacks such as high cost and harsh weather. Water level monitoring system helps in forecasting early river disasters and maintenance of the water body area. However, the early river disaster warning system introduces many conflicting requirements. Surveillance camera based water level detection system depends on either the area of interest from the water body or on optical flow algorithm. This proposed system is focused on water scaling area of a river or dam to detect water level. After the detection of scale area from water body, the proposed algorithm will immediately focus on the digits available on that area. Using the numbers on the scale, water level of the river is predicted. This proposed system is successfully tested on different water bodies to detect the water level area and predicted the water level.

Terrain Geometry from Monocular Image Sequences

  • McKenzie, Alexander;Vendrovsky, Eugene;Noh, Jun-Yong
    • Journal of Computing Science and Engineering
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    • 제2권1호
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    • pp.98-108
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    • 2008
  • Terrain reconstruction from images is an ill-posed, yet commonly desired Structure from Motion task when compositing visual effects into live-action photography. These surfaces are required for choreography of a scene, casting physically accurate shadows of CG elements, and occlusions. We present a novel framework for generating the geometry of landscapes from extremely noisy point cloud datasets obtained via limited resolution techniques, particularly optical flow based vision algorithms applied to live-action video plates. Our contribution is a new statistical approach to remove erroneous tracks ('outliers') by employing a unique combination of well established techniques-including Gaussian Mixture Models (GMMs) for robust parameter estimation and Radial Basis Functions (REFs) for scattered data interpolation-to exploit the natural constraints of this problem. Our algorithm offsets the tremendously laborious task of modeling these landscapes by hand, automatically generating a visually consistent, camera position dependent, thin-shell surface mesh within seconds for a typical tracking shot.

무인선의 비전기반 장애물 충돌 위험도 평가 (Vision-Based Obstacle Collision Risk Estimation of an Unmanned Surface Vehicle)

  • 우주현;김낙완
    • 제어로봇시스템학회논문지
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    • 제21권12호
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    • pp.1089-1099
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    • 2015
  • This paper proposes vision-based collision risk estimation method for an unmanned surface vehicle. A robust image-processing algorithm is suggested to detect target obstacles from the vision sensor. Vision-based Target Motion Analysis (TMA) was performed to transform visual information to target motion information. In vision-based TMA, a camera model and optical flow are adopted. Collision risk was calculated by using a fuzzy estimator that uses target motion information and vision information as input variables. To validate the suggested collision risk estimation method, an unmanned surface vehicle experiment was performed.

보행에서 동작변화 탐지 (Detection of Motion Change in Walking)

  • 이상용;김영백
    • 한국지능시스템학회:학술대회논문집
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    • 한국퍼지및지능시스템학회 2007년도 춘계학술대회 학술발표 논문집 제17권 제1호
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    • pp.315-319
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    • 2007
  • This paper presents a algorithm, what is able to recognize 4 different continuous human motion using a single stationary camera as input. For the first step, we acquire images from a camera. To enhance the image, we perform preprocessing which deals with removing noise using median filter, thresholding. And then morphological operations are performed to remove which small blobs and eliminates small holes. At the forth step, blobs are analysed to extracts for foreground region. Then, motions are predicted from these images by using optical flow technique, and the predicted motion data are refined by comparing our cardboard models so as to judge behavior pattern.

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Haar-like feature를 이용한 얼굴 검출과 추적을 위한 Lucas-Kanade특징 추적 (Face detection using haar-like feature and Tracking with Lucas-Kanade feature tracker)

  • 김기상;김세훈;박진영;최형일
    • 한국HCI학회:학술대회논문집
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    • 한국HCI학회 2008년도 학술대회 1부
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    • pp.835-838
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    • 2008
  • 본 논문에서는 얼굴 영역을 자동으로 검출하여 실시간으로 얼굴의 특징 짐을 추적하는 방법을 제안한다. Haar-like feature를 이용하여 얼굴 영역을 자동으로 추출하였으며, 회전에 강건한 KLT 알고리즘을 적용하여 얼굴의 특징 점들을 추출하였다. 그리고 실시간으로 얼굴의 특징점을 추적하기 위해 Lucas-Kanade 특징 추적 알고리즘을 사용하였다. 실험결과를 통하여 회전과 움직임에 강건하게 얼굴 영역을 검출하고 추적되는 것을 확인하였다.

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유한체적법을 이용한 밀폐공간내의 자연대류-복사열전달 해석 (Analysis of natural convection-radiation heat transfer using the finite volume method in enclosure)

  • 박광수;박경우;박희용
    • 설비공학논문집
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    • 제10권1호
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    • pp.95-107
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    • 1998
  • Natural convection and radiation heat transfer in a square enclosure containing absorbing, emitting, and isotopically scattering(participating) media is studied numerically using the finite volume method. Various numerical methods are employed to analyze the radiative heat transfer. However, it is very difficult to choose the proper method. In present study, a finite volume method(FVM) and a discrete ordinates method(DOM) are compared in rectangular enclosure. The SIMPLER algorithm is used to solve the momentum and energy equations. Thermal and flow characteristics are investigated according to the variation of radiation parameters such as optical thickness and scattering albedo. The result shows that the accuracy and the computing time of FVM are better than those of DOM in regular geometry.

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스테레오 연속 영상을 이용한 구조 복원의 정제 (A New Refinement Method for Structure from Stereo Motion)

  • 박성기;권인소
    • 제어로봇시스템학회논문지
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    • 제8권11호
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    • pp.935-940
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    • 2002
  • For robot navigation and visual reconstruction, structure from motion (SFM) is an active issue in computer vision community and its properties arc also becoming well understood. In this paper, when using stereo image sequence and direct method as a tool for SFM, we present a new method for overcoming bas-relief ambiguity. We first show that the direct methods, based on optical flow constraint equation, are also intrinsically exposed to such ambiguity although they introduce robust methods. Therefore, regarding the motion and depth estimation by the robust and direct method as approximated ones. we suggest a method that refines both stereo displacement and motion displacement with sub-pixel accuracy, which is the central process f3r improving its ambiguity. Experiments with real image sequences have been executed and we show that the proposed algorithm has improved the estimation accuracy.

비디오 기반의 질감 전이 기법 (Texture Transfer Based on Video)

  • 콩푸팔라;이호창;윤경현
    • 한국정보과학회:학술대회논문집
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    • 한국정보과학회 2012년도 한국컴퓨터종합학술대회논문집 Vol.39 No.1(C)
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    • pp.406-407
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    • 2012
  • Texture transfer is a NPR technique for expressing various styles according to source (reference) image. By late 2000s, there are many texture transfer researches. But video base researchers are not active. Moreover, they didn't use important feature like directional information which need to express detail characteristics of target. So, we propose a new method to generate texture transfer animation (using video) with directional effect for maintaining temporal coherence and controlling coherence direction of texture. For maintaining temporal coherence, we use optical flow and confidence map to adapt for occlusion/disocclusion boundaries. And we control direction of texture for taking structure of input. For expressing various texture effects according to different regions, we calculate gradient based on directional weight. With these techniques, our algorithm can make animation result that maintain temporal coherence and express directional texture effect. It is reflect the characteristics of source and target image well. And our result can express various texture directions automatically.

이미지 처리를 통한 공기 중 섬유의 자동계수 알고리즘 프로그램 개발 (Developing Image Processing Program for Automated Counting of Airborne Fibers)

  • 최성원;이희공;이종일;김현욱
    • 한국산업보건학회지
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    • 제24권4호
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    • pp.484-491
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    • 2014
  • Objectives: An image processing program for asbestos fibers analyzing the gradient components and partial linearity was developed in order to accurately segment fibers. The objectives were to increase the accuracy of counting through the formulation of the size and shape of fibers and to guarantee robust fiber detection in noisy backgrounds. Methods: We utilized samples mixed with sand and sepiolite, which has a similar structure to asbestos. Sample concentrations of 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, and 3%(w/w) were prepared. The sand used was homogenized after being sieved to less than $180{\mu}m$. Airborne samples were collected on MCE filters by utilizing a personal pump with 2 L/min flow rate for 30 minutes. We used the NIOSH 7400 method for pre-treating and counting the fibers on the filters. The results of the NIOSH 7400 method were compared with those of the image processing program. Results: The performance of the developed algorithm, when compared with the target images acquired by PCM, showed that the detection rate was on average 88.67%. The main causes of non-detection were missing fibers with a low degree of contrast and overlapping of faint and thin fibers. Also, some duplicate countings occurred for fibers with breaks in the middle due to overlapping particles. Conclusions: An image detection algorithm that could increase the accuracy of fiber counting was developed by considering the direction of the edge to extract images of fibers. It showed comparable results to PCM analysis and could be used to count fibers through real-time tracking by modeling a branch point to graph. This algorithm can be utilized to measure the concentrations of asbestos in real-time if a suitable optical design is developed.