Stereo Pair Matching Research Articles

Topographic Measurement Of Internal Surfaces Using a Sequence of Stereo Charge-Coupled DeVice Endoscopic Images: (1) Method

In endoscopic diagnosis, there has been a strong requirement to measure the internal surface topography of the rectum or esophagus. Accurate measurement, however, is very difficult, because the object is usually observed from an inclined view. In this paper, we propose a method to overcome this difficulty utilizing sequential stereo-pair images; the relative shape is roughly measured from sequential images taken by one of the change coupled device (CCD) cameras, and the size is determined by stereo-pair matching using the measured shape. A coarse-to-fine approach is also used to improve the resolution of topographic measurement. Through a basic experiment using a monocular CCD endoscope and a polyp phantom, the proposed method is confirmed to improve measurement accuracy in comparison with conventional methods.

246 二値化画像相関法に基づく3時刻3-D PTV計測

This paper proposes a new three consecutive time picture cross-correlation 3-D PTV (Particle Tracking Velocimetry), which is based on the combination of the binary image cross-correlation 2-D particle tracking between two projected screens, stereo pair matching and 3-D particle identification on three consecutive time pictures at regular time intervals. The present technique is applied to measure the flow structure of a weak bubbling-jet two-phase flow, and as a result, about one-hundred and fifty particle velocity vectors in the liquid motion and several higher velocity vectors of air bubbles are successfully measured.

3次元PTVのための粒子位置の計測法

In this paper, a new efficient measuring method of the three-dimensional coordinates of distributed tracers is proposed. In general, a method of measuring the coordinates is one of the key processes in the three-dimensional particle tracking velocimetry (PTV). Because theaccuracy of the measurement influences not only the reliability of the measured velocities but also the efficiency in finding stereo-pairs and the performance in tracing motion of tracers.The performance of the present method is achieved by two algorithms for stereo-pair matching and accuracy improvement which are based on a conditional arrangement of cameras.

Stereo by incremental matching of contours

Contours made of sequences of adjacent edge points are used as primitives in stereo pair matching. Matching contour segments, rather than the traditional epipolar edge points, can greatly reduce possible ambiguity. This is done by reformulating point-matching constraints to apply to contour matching, and by introducing a unique incremental matching scheme. Best-matched contours are paired first, constraining through neighborhood support their neighboring contours. Examples of the proposed stereo matching scheme are shown, with very few errors, for aerial images of natural terrain.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Use of color image correlation in the retrieval of gastric surface topography by endoscopic stereopair matching

We propose finding an optimal generalized color plane to carry out digital color image correlation. We seek the optimization of the correlation peak's sharpness and, for the purpose of analysis, we make some assumptions regarding the statistical properties of images to be considered. The analysis leads to a simple solution involving a projection onto the Karhunen-Loeve vectors corresponding to the smallest eigenvalues of the interprimary colors covariance matrix. We use our results in the retrieval of the gastric mucosal surface structure from stereopairs taken through an endoscope. Study of the statistics of the endoscope images shows that the assumptions used earlier can be applied to this type of image. We present some results of stereopair matching with color image correlation. We conclude by proposing a pseudo-3-D surface reconstruction of the gastric surface by mapping the endoscopic image onto the retrieved elevation information.

Image processing of tracer particle motions as applied to mixing and turbulent flow—I. The technique

Techniques of digital image processing of stereoscopic motion pictures are presented which were used to automate the tracking of neutrally buoyant tracer particles in turbulent flow. A software package is described which performed the following tasks: (1) particle image identification, (2) particle image tracking and (3) stereo pair matching of particle trajectories. Various criteria and objective functions are given which were used to accomplish the tasks.

Application Of Image Processing To The Analysis Of Three-Dimensional Flow Fields

A new method has been developed to apply image processing tech-niques to a more conventional stereoscopic measurement method. This new technique will provide both qualitative information and quantitative data, which are needed to achieve a better characterization of complex flow fields such as those in agitated vessels. The technique of flow visualization has been widely used to acquire qualitative realizations of flow structures and mixing mecha-nisms. However, the quantity of data obtained from such flow visualization studies has always been limiting. Sheu et al. [Chem. Eng. Comm. 17, 67 (1982)] used a stereoscopic cine camera to record the flow field in an agitated tank containing small, neutrally buoyant tracer particles and showed that three-dimensional velocities can be obtained from discrete sets of particle locations in stereo scenes. In this paper, the application of digital image processing to automate data acquisition procedures is presented. Instead of tracking particles manually, films (visual images) were digitized and were stored in digital form on magnetic tapes. A software package, utilizing THRESHOLDING and PATTERN MATCHING, has been developed to perform the following tasks: (1) particle image identification, (2) particle image tracking in consecutive frames, (3) stereo pair matching of particle trajectories, and (4) velocities evaluation in three-dimensional space evolving in time. The important attributes for flow characterization, such as velocity, acceleration, turbulent intensity, and possi-bly temperature, can be collected for analysis in much larger quantities at a much faster rate than ever before. Furthermore, considerable improvement in accuracy over that of a manually tracked method is also achieved. Most attrac-tive of all, this new combination of image processing and stereoscopic motion pictures is capable of providing sufficient data with high resolution to character-ize the flow field from a Lagrangian/Eulerian point of view.

PTV Measurement Of A Three-dimensionalParticle Motion In A Bubbling Jet MixingWater Vessel

The present paper proposes a new stereo pair matching technique with correction of light refraction at water-air boundary using two video pictures and a new particle tracking algorithm for three-dimensional particle-tracking velocimetry (3D PTV) based on a cross-correlation method using twoconsecutive-time-step binary pictures. The technique of 3D PTV is applied to measure three-dimensional velocity vectors of tracer particle motion in a cylindrical water vessel with a bottom blowing bubbling jet. The performance of stereo pair matching and the measurement results of the bubble-water twophase flows are discussed, and as a result the proposed technique is shown to be useful in measuring the threedimensional bubbling jet flow field.