In order to acquire sequence images in PIV measurement system of continuous clashing flow of water, two laser flashers,
the red one and the green one, are used in PIV measurement system. After the digital camera is triggered, the two
flashers flash in a short interval during the exposure period. The red light and the green light illuminate the same region
so that the image records the movements of tracing particles in two colors. Using digital image process technology, two
images, the red one and the green one, can be obtained from the original image. Based on the two images, the flow field
parameters can be calculated. The method possesses predominant advantages: high speed field can be measured using an
ordinary camera and the two images have determinate time labels, so the moving direction of the particles can be
determined easily. The main steps of the method include the transition from Bayer matrix to RGB matrix, the
pretreatment of the images, the analyzation of the velocity and the arrangement of the results.
This paper introduced our newly developed method to acquire three-dimensional images of a dental cast. A rotatable table, a laser-knife, a mirror, a CCD camera and a personal computer made up of a three-dimensional data acquiring system. A dental cast is placed on the table; the mirror is installed beside the table; a linear laser is projected to the dental cast; the CCD camera is put up above the dental cast, it can take picture of the dental cast and the shadow in the mirror; while the table rotating, the camera records the shape of the laser streak projected on the dental cast, and transmit the data to the computer. After the table rotated one circuit, the computer processes the data, calculates the three-dimensional coordinates of the dental cast's surface. In data processing procedure, artificial neural networks are enrolled to calibrate the lens distortion, map coordinates form screen coordinate system to world coordinate system. According to the three-dimensional coordinates, the computer reconstructs the stereo image of the dental cast. It is essential for computer-aided diagnosis and treatment planning in orthodontics. In comparison with other systems in service, for example, laser beam three-dimensional scanning system, the characteristic of this three-dimensional data acquiring system: a. celerity, it casts only 1 minute to scan a dental cast; b. compact, the machinery is simple and compact; c. no blind zone, a mirror is introduced ably to reduce blind zone.
The purpose of this article is to introduce the outline of our newly developed computer-aided 3D dental cast analyzing system with laser scanning, and its preliminary clinical applications. The system is composed of a scanning device and a personal computer as a scanning controller and post processor. The scanning device is composed of a laser beam emitter, two sets of linear CCD cameras and a table which is rotatable by two-degree-of-freedom. The rotating is controlled precisely by a personal computer. The dental cast is projected and scanned with a laser beam. Triangulation is applied to determine the location of each point. Generation of 3D graphics of the dental cast takes approximately 40 minutes. About 170,000 sets of X,Y,Z coordinates are store for one dental cast. Besides the conventional linear and angular measurements of the dental cast, we are also able to demonstrate the size of the top surface area of each molar. The advantage of this system is that it facilitates the otherwise complicated and time- consuming mock surgery necessary for treatment planning in orthognathic surgery.
This article is to introduce the outline of our newly developed method of laser measurement for slight deformation of large-scale building or structure, which we call the automatic inspection for the six-degree-of-freedom movement-deformation of distributed interconnected measure-points. The basic principle is described as below: A certain number of measure-points are settle on the building that is waiting for inspection. In all measure-points, we select one as a datum point. For every two connected measure- points, we measure their relative displacement of six-degree-of- freedom, then, we calculate out the relative displacement of six- degree-of-freedom for every measure-point to datum point. By this way, we can know the deformation of the building. The measuring method of relative displacement for every two connected measure-points is presented as below: An indium steel pipe, which acts as a length rod and a displacement sensor, are used to inspect the distance of the two measure-point. A collimating laser beam and a two-dimensional PSD are used to inspect the other two dimensional linear displacement. A collimating laser beam, a reflector and a one-dimensional PSD are used to inspect the relative rotation in horizontal plane. A high precision photoelectric tiltmeter which is especially developed for this purpose is used to inspect the other two dimensional angular displacement. All those measurement are controlled by a central computer, and full automatic.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.