Digital camera nonlinear calibration method based on LCDs

A technology of a digital camera and a calibration method, applied in the field of measurement, can solve the problems that affect the image shooting quality, the shooting angle is too large, the image is not clear, etc., and achieve the effects of geometric deformation approaching perfection, high image quality, and high calibration accuracy.

Inactive Publication Date: 2010-03-17
QINGDAO UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the existence of the viewing angle of the screen, when shooting the LCD display, if the shooting angle is too large, color distortion will occur, the image will not be clear, and the quality of the image will be affected.

Method used

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  • Digital camera nonlinear calibration method based on LCDs
  • Digital camera nonlinear calibration method based on LCDs
  • Digital camera nonlinear calibration method based on LCDs

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] The specific process and steps of this embodiment include:

[0020] 1. Draw a calibration table and take an image

[0021] The calibration table used in this embodiment is as follows figure 1As shown, N rows and M columns of easily identifiable feature dots are distributed on it, and the diameters of 5 feature dots are obviously larger than the diameters of other feature dots, and the positions of the asymmetrically distributed 5 large dots can be distinguished Their respective identities; in addition, these 5 big circles are also used to determine the coordinate axis of the calibration table and the positioning and identification of other dots; take the center of the feature point in the upper left corner of the calibration table as the origin, and take the longer one of the calibration table as the origin The side is the x-axis, and the right is positive; the shorter side is the y-axis, and the downward is positive; take several images of the calibration table by rot...

Embodiment 2

[0076] This embodiment adopts the FinePix S5Pro digital camera that resolution is 4256 * 2848; The AF Nikkor optical lens that focal length is 24mm; ASUS X81H32SE-SL notebook computer, liquid crystal display screen size is 14.1 inches, resolution 1280 * 800, and dot pitch is 0.2375 mm; the calibration program is written with VC++6.0 and OpenCV, and runs on the WindowsXP system; the designed calibration table is as follows figure 1 , the diameter of the small circle is 4.75mm, the diameter of the large circle is 9.50mm, and the distance between the centers is 20.425mm.

[0077] First, the calibration table is displayed on the liquid crystal display LCD, and a digital camera is used to rotate the calibration table in the LCD (the optical axis is perpendicular to the LCD screen) around the optical axis to capture 4 images, and use the captured images to perform calibration experiments. The calibration result obtained is:

[0078] K = ...

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Abstract

The invention belongs to the technical field of measured calibration, and relates to a calibration process for solving camera inside and outside parameters by using a single digital camera for shooting a group of images based on LCDs, particularly to a digital camera nonlinear calibration method based on the LCDs, which comprises the following steps: designing and drawing a calibration chart through programming, wherein the calibration chart has round marking points in different sizes; displaying the calibration chart on the screen of a liquid crystal display; then shooting images by a digitalcamera in the mode of rotating around an optical axis; and then computing the camera inside and outside parameters by using the shot images; extracting sub-pixel contour edges in the images by usingthe complete pure flatness of the liquid crystal display and easy detection of centralized positioning height and sub-pixel edge contour of the round marked points, and obtaining a calibration resultof digital camera parameters by a nonlinear optimization method. The calibration method has the advantages of simple and easy operation, small and agile use equipment, good calibration precision, goodquality, strong optimization degree and the like.

Description

Technical field: [0001] The invention belongs to the technical field of measurement, and relates to a calibration method for solving camera internal and external parameters by shooting a group of LCD-based images with a single digital camera, which can be applied to on-site calibration of photogrammetry and computer vision. Background technique: [0002] Three-dimensional reconstruction starts from the two-dimensional image information acquired by the camera, calculates the geometric information such as the three-dimensional position and shape of the object, and reconstructs and recognizes the object in the scene. The key to 3D reconstruction is how to correspond the point on the 2D image with the 3D geometric position of a point on the surface of the space object. And this correspondence is determined by the geometric model of camera imaging, the parameters of these models are called camera parameters, and the process of calculating these parameters is called camera calibra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T7/00
Inventor 张维忠潘振宽油世明王靖
Owner QINGDAO UNIV
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