Research On Precision Measurement Technology Based On Digital Photogrammetry For Large Objects

With the development of modern industry, large-size measurements have been made clear expectations and requirements in various fields of production and engineering, digital photogrammetry technology has been widely used in large-size precision measurement. Industrial digital photogrammetry is a new detection technology which is based on the professional camera photography and computer image processing, its research focused on the geometry size and location of objects in space, posture and so on. Digital imaging device model and the calibration and high precision sub-pixel positioning is the core technology in digital photogrammetry.This article focuses on the analysis of basic principles of digital photogrammetry, combined with digital photography imaging model, strictly derived photogrammetry in the total line equation. First, through the deep study of digital image processing techniques, the basic principle of Hough transform and sub-pixel positioning technology, a new method is proposed based on Hough transform for detecting straight lines and circular sub-pixel location algorithm; Second, through the research on classical model and calibration method, a new calibration model and its amendment, solution method which is based on two-dimensional direct linear transformation is proposed. Next, pairs of sub-pixel location algorithm and camera calibration algorithm have been checked by simulation and experiment,its results were very good, sub-pixel positioning accuracy can reach 0.02pixel, camera system calibration error can control within 0.005mm. Finally, with the combination of image measurement techniques and the results of the research of this paper, designed and implemented a set of digital photogrammetry measurement system.