The actual size of the dot will vary based on the number of pixels of the camera and field of view selected of the camera. An optimal size is at least 9 pixels (3 x 3), which will ensure the camera will detect the dot accurately and IMAQ Vision will correctly process the dots.
The individual dots should be at least 4 pixels apart. This will prevent two or more dots from being processed as one dot.
The dots need to be in vertical and horizontal lines that are perpendicular to each other to make up the grid:
NI Vision ships with 3 calibration examples for LabVIEW that install by default in<labview>\examples\Vision\2. Functions\Calibration
You may use the calibration grid installed with NI Vision by selecting Start»All Programs»National Instruments»Vision»Documentation»Calibration Grid. The dots have radii of 2 mm and center-to-center distances of 1 cm. If your field of view is too small to view a large grid of dots at this scale, you can print the grid at a smaller scale.See NI Vision Concepts Help and Perspective and Nonlinear Distortion Calibration for more details on calibration grids and the calibration process.
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