This is a problem in the field of optics, which has its own standard definition in optics. The image created by taking a picture with a camera will be distorted.
As an example, we all have the experience of taking pictures with ordinary cameras. There is a lens called “wide-angle lens”, also known as “fisheye lens”, with this type of lens to take pictures, you will find that the image at the four sides of the photo is bent. This phenomenon is caused by the “lens distortion”. Example of saying “fisheye lens” because “fisheye lens” is a large distortion lens.
Lenses have distortion, the difference is only distortion is large and small. And for the visual inspection system, of course, is the hope that the lens distortion is as small as possible. This is because the vision system for detection, are on the image of the camera image. If the camera imaging on the “crooked”, then the system detection results will not be ” proper” .
There are two ways for Vision system for the correction of lens distortion.
(1) From the hardware:
With a very small distortion lens. This lens is called telecenter imaging lens.But its price is expensive as 6 times or more as the price of ordinary lenses.. The aberrations of such lenses are below 1%, and some can reach 0.1%. Most of the higher accuracy of the visual measurement system, with such lenses.
(2) From the software:
In the “camera calibration”, the use of calibration standard module on the dot matrix to calculate.
The specific method is: after the completion of the “camera calibration”, according to the known measurement of the size of each point in the dot matrix, to analyze the size of the points in the periphery of the dot matrix, and the size of the points in the inner circle of the dot matrix is different. By comparison can be derived from a ratio, this ratio is the lens distortion. With this ratio, in the actual measurement can be made to correct the distortion
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Post time: Oct-24-2022
