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Calibration board knowledge is introduced

by:Fugen      2020-10-13
In machine vision applications, the camera calibration technique need accurate camera parameters and external parameters as input and prerequisites of reconstruction algorithm, is currently the most popular camera calibration algorithm Tsai in 1987 [ Tsai1987] , Tsai method using a non coplanar with special identity of 3 d calibration content to provide the image point and its corresponding and calculate the corresponding three-dimensional point calibration parameters. Through the calibration algorithm, can calculate the projection matrix of camera, and provide the scene 3 d information measure. Without a given real scene of absolute translation, rotation and scale parameters, can achieve the level of similarity transformation measure refactoring. In order to meet the industry application of high-precision vision calibration, launched a series of machine vision calibration plate products, machine vision software have convenient access to the camera calibration result data. Is developed for universities, research institutes and machine vision integrator dedicated high-precision calibration tool. Are soda glass calibration plate material: material: Russia use the calibration board color is silver; Germany, Austria, periphery calibration board color is blue; The United States, Japan calibration board color is yellow. This color is the coating process decision, you can't judge the merits of the calibration plate color alone. Domestic high-end calibration board color is yellow, other color cost is relatively low. Standard production process: glass substrate after polishing, cleaning, after coating, etc. Defects in the process of membrane layer is firm, post-production points less. If some process to reduce or use of the machine is not very good, make the product, the cost will be a lot cheaper, at the same time, the quality is not very good. Example: if made, according to normal process size is 63 mm * 63 mm, a large number of production is also at least one hundred yuan of above. Material 2: ceramic base of standard plate has a small thermal expansion coefficient, high strength, high hardness, good wear resistance, low thermal conductivity, excellent acid-proof alkaline, etc, and its good surface diffuse processing, solved in the process of application, the front light cases the problem of reflective glass calibration plate, can better identify plate design detail information so as to achieve a higher calibration precision and accuracy of measurement. Materials three: quartz material, good pervious to light, the biggest advantage: expansion coefficient is small. In the process of calibration instruments, affected by the environment temperature is small. The corresponding cost is also high. Quartz material points JGS1 and JGS2. JGS1 is expensive. JGS2 is relatively cheap, with bubbles. In the selection of calibration board must consider the use environment, precision, etc. , choose the appropriate calibration plate. Accuracy and ratio visible defects can lead to batch price differences occurred several times. Calibration plate generally has two kinds: 1) Solid circular array pattern 2) A chess board pattern
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