• Title, Summary, Keyword: 3-D velocity vector

Search Result 48, Processing Time 0.043 seconds

Recovery of 3-D Motion from Time-Varying Image Flows

  • Wohn, Kwang-Yun;Jung, Soon-Ki
    • Journal of Electrical Engineering and information Science
    • /
    • v.1 no.2
    • /
    • pp.77-86
    • /
    • 1996
  • In this paper we deal with the problem of recovering 3-D motion and structure from a time-varying 2-D velocity vector field. A great deal has been done on this topic, most of which has concentrated on finding necessary and sufficient conditions for there to be a unique 3-D solution corresponding to a given 2-D motion. While previous work provides useful theoretical insight, in most situations the known algorithms have turned out to be too sensitive to be of much practical use. It appears that any robust algorithm must improve the 3-D solutions over time. As a step toward such algorithm, we present a method for recovering 3-D motion and structure from a given time-varying 2-D velocity vector field. The surface of the object in the scene is assumed to be locally planar. It is also assumed that 3-D velocity vectors are piecewise constant over three consecutive frames (or two snapshots of flow field). Our formulation relates 3-D motion and object geometry with the optical flow vector as well as its spatial and temporal derivatives. The linearization parameters, or equivalently, the first-order flow approximation (in space and time) is sufficient to recover rigid body motion and local surface structure from the local instantaneous flow field. We also demonstrate, through a sensitivity analysis carried out for synthetic and natural motions in space, that 3-D motion can be recovered reliably.

  • PDF

Development of High-resolution 3-D PIV Algorithm by Cross-correlation (고해상도 3차원 상호상관 PIV 알고리듬 개발)

  • Kim, Mi-Young;Choi, Jang-Woon;Lee, Hyun;Lee, Young-Ho
    • Proceedings of the KSME Conference
    • /
    • /
    • pp.410-416
    • /
    • 2001
  • An algorithm of 3-D particle image velocimetry(3D-PIV) was developed for the measurement of 3-D velocity field of complex flows. The measurement system consists of two or three CCD camera and one RGB image grabber. In this study, stereo photogrammetty was applied for the 3-D matching of tracer particles. Epipolar line was used to decect the stereo pair. 3-D CFD data was used to estimate algorithm. 3-D position data of the first frame and the second frame was used to find velocity vector. Continuity equation was applied to extract error vector. The algorithm result involved error vecotor of about 0.13 %. In Pentium III 450MHz processor, the calculation time of cross-correlation for 1500 particles needed about 1 minute.

  • PDF

Development of 3-D Stereo PIV (3차원 스테레오 PIV 개발)

  • Kim Mi-Young;Choi Jang-Woon;Nam Koo-Man;Lee Young-Ho
    • 한국가시화정보학회:학술대회논문집
    • /
    • /
    • pp.19-22
    • /
    • 2002
  • A process of 3-D particle image velocimetry, called here, as '3-D stereo PIV' was developed for the measurement of a section field of 3-D complex flows. The present method includes modeling of camera by a calibrator based on the homogeneous coordinate system, transfromation of oblique-angled image to transformed image, identification of 2-D velocity vectors by 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system and finally 3-D animation as the post processing. In principle, as two frame images only are necessary for the single instantaneous analysis of a section field of 3-D flow, more effective vectors are obtainable contrary to the previous multi-frame vector algorithm. An experimental system was also used for the application of the proposed method. Three analog CCD cameras and an Argon-Ion Laser(300mW) for illumination were adopted to capture the wake flow behind a bluff obstacle.

  • PDF

Swimming speed measurement of Pacific saury (Cololabis saira) using Acoustic Doppler Current Profiler (음향도플러유향유속계를 이용한 꽁치어군의 유영속도 측정)

  • Lee, Kyoung-Hoon;Lee, Dae-Jae;Kim, Hyung-Seok;Park, Seong-Wook
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.46 no.2
    • /
    • pp.165-172
    • /
    • 2010
  • This study was performed to estimate the swimming velocity of Pacific saury (Cololabis saira) migrated offshore Funka Bay of Hokkaido using an acoustic Doppler current profiler (OceanSurveyor, RDI, 153.6kHz) established in T/S Ushio-maru of Hokkaido University, in September 27, 2003. The ADCP's doppler shift revealed as the raw data that the maximum swimming velocity was measured 163.0cm/s, and its horizontal swimming speed and direction were $72.4{\pm}24.1\;cm/s$, $160.1^{\circ}{\pm}22.3^{\circ}$ while the surrounding current speed and direction were $19.6{\pm}8.4\;cm/s$, $328.1^{\circ}{\pm}45.3^{\circ}$. To calculate the actual swimming speed of Pacific saury in each bins, comparisons for each stratified bins must be made between the mean surrounding current velocity vectors, measured for each stratified bin, and its mean swimming velocity vectors, assumed by reference (threshold > -70dB) and 5dB margin among four beams of ADCP. As a result, the actual averaged swimming velocity was 88.6cm/s and the averaged 3-D swimming velocity was 91.3cm/s using the 3-D velocity vector, respectively.

Development and Application of High-resolution 3-D Volume PIV System by Cross-Correlation (해상도 3차원 상호상관 Volume PIV 시스템 개발 및 적용)

  • Kim Mi-Young;Choi Jang-Woon;Lee Hyun;Lee Young-Ho
    • Proceedings of the KSME Conference
    • /
    • /
    • pp.507-510
    • /
    • 2002
  • An algorithm of 3-D particle image velocimetry(3D-PIV) was developed for the measurement of 3-D velocity Held of complex flows. The measurement system consists of two or three CCD camera and one RGB image grabber. Flows size is $1500{\times}100{\times}180(mm)$, particle is Nylon12(1mm) and illuminator is Hollogen type lamp(100w). The stereo photogrammetry is adopted for the three dimensional geometrical mesurement of tracer particle. For the stereo-pair matching, the camera parameters should be decide in advance by a camera calibration. Camera parameter calculation equation is collinearity equation. In order to calculate the particle 3-D position based on the stereo photograrnrnetry, the eleven parameters of each camera should be obtained by the calibration of the camera. Epipolar line is used for stereo pair matching. The 3-D position of particle is calculated from the three camera parameters, centers of projection of the three cameras, and photographic coordinates of a particle, which is based on the collinear condition. To find velocity vector used 3-D position data of the first frame and the second frame. To extract error vector applied continuity equation. This study developed of various 3D-PIV animation technique.

  • PDF

The Study on Optimum Ventilation System during Long Tunnel Construction (굴착중인 장대터널 내 최적의 환기시스템에 관한 연구)

  • Lim, Han-Uk;Oh, Byung-Hwa
    • Journal of Industrial Technology
    • /
    • v.26 no.A
    • /
    • pp.3-15
    • /
    • 2006
  • To determine the optimum ventilation systems during long tunnel excavation, the velocity vector profile and the contaminant's distribution at working place are studied using 2-D, 3-D numerical analysis. The main results can be summarized as follow; In case of long tunnels, blower-exhaust-mixture types which enable to use soft blast ducts is most appropriate in terms of ventilation and economical efficiency. Of the same ventilation types, ventilation efficiency has a difference according to blast ducts and the distance between fan and working place. The 3-D numerical result shows that arranging blower and exhaust ducts in the right and left corners of the tunnel respectively is effective to discharge contaminant. The result of the real measurement shows that CO concentration can be reduced to below 50 ppm, which is regulation value, as 16-minutes fan operation goes on.

  • PDF

The Vibration Velocity and Vibration Level of Near-field Blasting Vibration in an Urban Blasting Site (근접장 발파진동에서 진동속도와 진동레벨의 비교)

  • Lee, Yeon-Soo;Chang, Seo-Il
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.15 no.8
    • /
    • pp.918-923
    • /
    • 2005
  • The vibration level (dB(V)) and vibration velocity (cm/sec) on the ground and buildings due to the differences of the measuring sites from the blasting source was investigated. To compare with vibration level and vibration velocity theirs magnitude was not surely directly proportional and vibration velocity 0.1 cm/sec was $45\~50$ dB(V). The difference between the measured vibration level and the calculated vibration level by Ejima's equation using vibration velocity PVS(peak vector sum) showed $21.0\~30.9$ dB(V) on the ground, $15.3\~23.6$ dB(V) on the apartment, respectively. And the correlation of vibration velocity and nitration level at the measuring sites of lower altitude showed higher than that of higher altitude.

Measurement of vertical migration speed of Sound Scattering Layer using an bottom mooring type Acoustic Doppler Current Profiler (해저설치형 음향도플러유향유속계를 이용한 음향산란층의 연직이동속도 측정)

  • Jo, Hyeon-Jeong;Lee, Kyoung-Hoon
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.46 no.4
    • /
    • pp.449-457
    • /
    • 2010
  • This study shows that the vertical migration speed of sound scattering layers (SSLs), which is distributed in near Funka Bay, were measured by 3D velocity components acquired from a bottom moorng ADCP. While the bottom mooring type has a problem to measure the velocity vectors of sound scattering layer distributed near to surface, both the continuous vertical migration patterns and variability of backscatterers were routinely investigated as well. In addition, the velocity vectors were compared with the vertical migration velocity estimated from echograms of Mean Volume Backscattering Strength, and estimated to produce observational bias due to SSLs which is composed of backscatterers such as euphausiids, nekton, and fishes have swimming ability.

Development of 3-D Stereo PIV by Homogeneous Coordinate System (호모지니어스 좌표계를 이용한 3차원 스테레오 PIV 알고리듬의 개발)

  • Kim, Mi-Young;Choi, Jang-Woon;Nam, Koo-Man;Lee, Young-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.27 no.6
    • /
    • pp.736-743
    • /
    • 2003
  • A process of 3-D particle image velocimetry, called here, as '3-D stereo PIV' was developed for the measurement of an illuminated slied section field of 3-D complex flows. The present method includes modeling of camera by a calibrator based on the homogeneous coordinate system, transfromation of the oblique-angled image to the right-angled image, identification of 2-D velocity vectors by 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterior, and finally 3-D animation as the post processing. An experimental system was also used for the application of the proposed method. Three analog CCD cameras and an Argon-Ion Laser(300mW) for illumination were adopted to capture the wake flow behind a bluff obstacle.

Development of Torque Monitoring System of Induction Spindle Motor using Graphic-programming (Graphic-programming 을 이용한 주축용 유도전동기의 토크감시시스템 개발)

  • Lee, In-Hwan;Kwon, Won-Tae
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.18 no.10
    • /
    • pp.184-193
    • /
    • 2001
  • In vector control technique, stator currents of an induction motor are transformed to equivalent d-q currents in a reference frame consist of d and q axis, each of which is coincide with flux and torque direction respectively. Since the current in q-axis is related to the torque in a synchronously rotating frame, torque is estimated as a function of q-axis current and flux. In this paper, a method to estimate torque of an induction motor based on the measurement of 3-phase currents and rotating velocity of a rotor is presented. Graphic-programming is used to measure signals, to estimate the torque and to show the result in the form of user friendly graph in window environment. To stabilize the fluctuation of estimated torque caused from the small measurement error of the rotor velocity, the stator current is reconstructed in a program based on measured signals. The experimental results executed under the velocity of 500 rpm, 1500 rpm without load and 1500 rpm with load show that the proposed method estimates the torque very well.

  • PDF