Orthogonal projection emendation method for image measurement in industry close range photography

Abstract

An orthographic projectional correction method of a close shot photogrammetric image used in an industry relates to the technical field of an image processing and solves the technical problems that the accuracy and the efficiency of the photogrammetric image are low; the orthographic projectional method creates a back projection transformational model by utilizing a shooting distance, a shooting angle and an imaging law of an isometric object; the steps of the method are as follows: 1) an extreme value of a ratio relation of an image size of the isometric object and a vertex angle along the horizontal direction of a camera lens are respectively obtained; 2) corresponding relations between the four pairs of points C-c, D-d, E-e and F-f are obtained: 3) by the back projection transformation, an area abcd of the image is converted into the ladder-shaped area ABCD. The orthographic projectional correction method of the invention has the advantages that the accuracy and the efficiency of an automatic decoding algorithm are enhanced, a work load of a data acquisition and the time of a data processing are reduced, an utilization ratio of an encoding mark in the single image is improved, and the labour intensity of the on-the-spot data acquisition is also reduced.

Description

technical field [0001] The invention relates to image processing technology, in particular to an orthographic correction method for measuring images in industrial close-range photography. Background technique [0002] Industrial close-range photogrammetry obtains the three-dimensional data of the measured object by measuring the coordinates of artificial marker points placed at key positions on the measured object. Its direct measurement objects are artificial landmarks, not the measured object itself. One type of artificial marker points that represent different encoded information through different patterns is called "coded markers". During on-site data collection, various artificial signs are placed around the measured object, and then photographed with a digital camera. The acquired image is processed to identify the codes of each coded mark. [0003] Some coded signs that are far away from the camera and have a large shooting angle cannot automatically recognize thei...

AI Technical Summary

Problems solved by technology

This will increase the workload of data collection and increase the time for data processing.

And when the shooting scene is very large, it is very likely that there will be missed shots, which will be unfavorable to the follow-up work

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