Checkerboard angular point automatic detection method under fish-eye lens

A fisheye lens and automatic detection technology, which is applied in image data processing, instruments, calculations, etc., can solve problems such as unsatisfactory fisheye lens image detection effects, and achieve the effect of getting rid of tediousness and improving speed and accuracy

Inactive Publication Date: 2015-11-04
NORTHEASTERN UNIV
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Problems solved by technology

However, these toolboxes do not make assumptions about the shape of the lens, and the detection effect of fisheye lens images with serious distortion is not ideal.
[0005

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  • Checkerboard angular point automatic detection method under fish-eye lens
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  • Checkerboard angular point automatic detection method under fish-eye lens

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Embodiment Construction

[0027] The present invention is illustrated by taking an 8×10 checkerboard distorted image under a fisheye lens as an example, see figure 2 .

[0028] Step 1: Since the external environment around the checkerboard picture will affect the detection of the checkerboard, it is necessary to shield useless information before doing Harris corner detection to improve the detection accuracy. The larger the outer white area in the checkerboard corner image, the easier it is to select a specific area. Ideally, only 4 points around the image need to be selected.

[0029] Step 2: Perform Harris corner detection on a specific area, see image 3 . The specific operations include: (1) Computing the correlation matrix M for each pixel; (2) Computing the Harris corner response of each pixel. Here R is a matrix of 576×702; (3) Find the maximum value point in the range of w×w, if the Harris corner point response is greater than the threshold, it is regarded as a corner point.

[0030] Here...

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Abstract

A checkerboard angular point automatic detection method under a fish-eye lens comprises the steps of selecting a particular region of a checkerboard and shielding useless information to reduce angular point detection time and raise detection precision; carrying out Harris angular point detection on the particular region; adding an angular point manual extraction step in an algorithm and manually adding the hidden angular point information; adding angular point combining operation according to the total number of checkerboard angular points and angular point separation situations; as for the checkerboard which is small in checkerboard rotating angle, slight in distortion and few in angular corner, sorting the angular points in a binomial fitting manner; and as for the checkerboard distorted under the fish-eye lens, calculating the sequence of the checkerboard angular points by using a modified convex hull algorithm. Simulation software is utilized to automatically detect coordinates of the checkerboard angular points, and under the condition of ensuring detection reliability of the angular points, the detection speed and precision of the angular points are greatly raised, and the complexity of manually extracting the checkerboard angular points is removed.

Description

technical field [0001] The invention relates to the field of machine vision, in particular to an automatic detection method for checkerboard corners under a fisheye lens. Background technique [0002] As the first condition of visual measurement, camera calibration aims to establish the transformation relationship between the image coordinate system and the space coordinate system. Camera calibration generally includes two steps: detection of image feature points and solution of camera parameters. As a typical calibration image, the checkerboard image has been widely used in camera calibration, and its corner detection has become one of the hot issues in computer vision. For the checkerboard image, the task of image feature point detection is not only to extract the image coordinates of each corner point in the checkerboard image, but also to establish a one-to-one correspondence between each image corner point and the spatial corner point. [0003] At present, the researc...

Claims

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Application Information

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IPC IPC(8): G06T7/00
Inventor 张云洲王少楠杨文纶张益凯张翰铎
Owner NORTHEASTERN UNIV
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