Circular Dot Calibration Board

The dot calibration grid is one of the most commonly used high-precision calibration tools in machine vision, industrial measurement, and computer vision (on par with the checkerboard calibration grid). It consists of an array of circular black and white dots, typically categorized as symmetrical or asymmetrical dot arrays.

1. Core Advantages and Features

(1) Extremely high sub-pixel accuracy: Dots possess natural geometric symmetry. By fitting the boundary of the entire circle or calculating the centroid, the algorithm can aggregate information from hundreds or thousands of pixels to determine the center position, achieving a positioning accuracy generally superior to traditional corner points (such as checkerboard corner points).

(2) Strong anti-distortion capability: Under conditions of wide viewing angles or severe lens distortion, feature extraction from dot arrays is more stable than from square corner points, reducing the likelihood of feature point drift or misidentification.

(3) High orientation discrimination: The asymmetric circle grid, by introducing a unique asymmetry in dot arrangement, allows the algorithm to automatically determine the orientation of the calibration grid in a single image, avoiding calculation errors caused by orientation reversal.

2. Main Application Scenarios

(1) Camera-based distortion calibration: Used to accurately calculate the camera's focal length, optical center, and lens distortion coefficient before machine vision 3D reconstruction, binocular stereo vision, or monocular ranging.

(2) Industrial high-precision measurement and photogrammetry: Commonly used in aerial photography, large workpiece 3D measurement, and automotive manufacturing, where high precision is required.

(3) Robot eye-hand calibration: Used in conjunction with the end-effector camera to establish precise mathematical transformations between the camera coordinate system and the robot arm coordinate system.

3. Customization Services (Parameters and materials can be customized; custom designs based on provided drawings are also available)

The dot calibration plate substrate is optional. Different substrates (such as glass, ceramics, film, aluminum plates, etc.) can be customized according to different application scenarios, environments, and precision requirements.

The following are some commonly used substrate parameter information:

1. Glass substrate parameters:

2. Ceramic substrate parameters:

3. Film substrate parameters:

Dongguan Dafan Optical Technology Co., Ltd.(DFOPTIX) was founded in 2018, its headquarters located in Dongguan City, Guangdong Province, China. DFOPIX is a system-level calibration solutions service provider with engineering culture as its cornerstone and technological innovation as its core.

Currently, DFOPTIX has nearly 150 employees, with R&D personnel consistently accounting for over 30% of the workforce each year — a professional team combining deep engineering expertise with sustained innovation capability.

DFOPTIX has established an advanced R&D and manufacturing base spanning nearly 20,000 square meters, equipped with high-standard precision workshops such as class-100 lithography workshop and class-1000 vacuum lamination workshop, as well as various well-equipped professional laboratories. It has also introduced internationally advanced manufacturing and testing equipment, systematically establishing an industry-leading R&D and manufacturing system.

DFOPTIX specializes in the R&D and manufacturing of a full category of calibration products — including integrated light-source calibration targets and LiDAR calibration boards, while also providing customized calibration product services tailored to customers’ requirements. To date, our company's products and solutions have been widely deployed across sectors including medical, semiconductor, robotics, consumer electronics, intelligent vehicles, aerospace, 3D scanning, and industrial automation. DFOPTIX has served over 3,000 clients, including several Fortune 500 companies.