For friends who are not engaged in the machine vision application industry, when it comes to the calibration board, some people may not know much about it, or even know what it is. In fact, the calibration plate has many functions, such as in applications such as measurement, photogrammetry, and 3D reconstruction, which are often inseparable from its use. So what exactly is a calibration board?
The calibration plate, in fact, is a geometric model with a fixed-pitch pattern array. The camera captures images through a flat panel with a fixed-pitch pattern array (ie, the calibration plate), and then calculates the geometric model of the captured image through calibration algorithms. In turn, high-precision measurement and reconstruction results are obtained, lens distortion is effectively corrected, and the accuracy of image measurement and photogrammetry in machine vision applications is greatly improved.
The calibration board only needs two steps to improve the accuracy of the machine vision system.
The first is error measurement and evaluation. The high-precision machine vision system can obtain the error value at any position within the field of view through the images collected by the calibration board and the professional calibration algorithm, and then evaluate the detection accuracy level of the machine vision system based on these error data.
The second is the correction and compensation of error images. The machine vision calibration board obtains the error data through the first step, and then starts to correct and compensate the position of each pixel information on the image. This process involves various precise image algorithms such as image translation, rotation, interpolation, reconstruction, and brightness compensation. After correcting and compensating the image, it can more accurately reflect the actual situation of the measured item and achieve the purpose of precise measurement and detection.
In applications such as image measurement, photogrammetry, and three-dimensional reconstruction, the main function of the calibration plate is to correct lens distortion, determine the conversion relationship between physical dimensions and pixels, and determine the three-dimensional geometric position of a point on the surface of a space object and its corresponding point in the image. The relationship between them needs to establish a geometric model of camera imaging.
