Based On An Image Reinforced Elongation Measurement Methods Research

Image measurement technology is researched mainly in this paper,which treat the image as means or vectors for detecting and transmitting the information.By collecting feature form the image,image measurement technology received the measured object's real information finally.The extending rate of the steel bar is a very important indicator for evaluating reinforced materials.This paper measured the extending rate of the steel bar use the image,the main research result described in this paper includes the flowing parts:Measurement model.Two methods of single image measurement are discussed and achieved.In the first method,the camera was first calibrated use the equality of cross ratio,then put the measured object and calibration object on the same plane,put the camera perpendicular to the calibration plane as far as possible,finally 3D reconstruction was transformed to 2D reconstruction,then the calculate becomes simple.In the second method,we first get the homography of the calibration plane,then obtain the homography of the measured plane use the vertical relationship,finally receive the measurement results.Camera calibration.In the paper,we choose the nonlinear model and consider the radial distortion only according to the measurement requirement,the equality of cross ratio in the perspective projection was used to calculate the first-order radial distortion factor and linear calibrate the camera.Image processing.In the paper,we divided the image processing into two parts:one for calibration object--planar grid,we choose the grid nodes extraction and corresponding based on former researcher's works;Another for white marker,we first use Hough transform extraction of straight line to determine the initial corner,then intensity vary detector was used to get the accurate corner coordinates.Data visualization.In the paper,the experimental data are used to reconstruction, then calculate the extending rate of the steel bar.So the data calculate module is designed and the results are saved to the files for the assurance of the data.After a series of works,such as theoretical analysis,system structure,experimental verification and measurement deviation analysis,we demonstrate this system has practical value and proposed improved idea,all of this illustrate that the system worth to be research further.