Calibration Board

You are currently viewing the documentation for the latest version (2.2.1). To access a different version, click the "Switch version" button located in the upper-right corner of the page.

■ If you are not sure which version of the product you are currently using, please feel free to contact Mech-Mind Technical Support.

Calibration board is usually used for intrinsic parameter check and hand-eye calibration. This article introduces the types, models, and mounting methods of calibration boards.

If you need the installation drawings and 3D models of calibration boards, click here to download them.

Calibration Board Types and Models

Mech-Mind provides two types of calibration boards: CGB and OCB.

CGB

The following figure shows a CGB-type calibration board (CGB-020 as an example).

cgb

  • The above figure is for reference only; the actual product may differ.

  • The CGB-type calibration board has a 5 x 4 number of calibration circles arranged asymmetrically.

  • d is the calibration circle spacing, that is, the distance along the horizontal/vertical direction between the centers of two adjacent calibration circles.

  • The CGB-type calibration board is one-piece and does not require an additional adapter plate.
Model Material d (mm) Rows Columns Dimensions (mm)

CGB-020

Carbon fiber

20

5

4

185 x 145 x 2

CGB-035

35

5

4

303 x 243 x 2

CGB-050

50

5

4

420 x 340 x 3

OCB

The following figure shows a OCB-type calibration board (OCB-005 as an example).

ocb

  • The above figure is for reference only; the actual product may differ.

  • The OCB-type calibration board has a 11 x 9 number of calibration circles.

  • d is the calibration circle spacing, that is, the distance along the horizontal/vertical direction between the centers of two adjacent calibration circles.

  • OCB-type calibration boards have no mounting holes and therefore cannot be mounted on the last joint of the robot. It can be used only when the camera is mounted in the eye in hand (EIH) mode.
Model Material d (mm) Rows Columns Dimensions (mm)

OCB-005

Glass

5

9

11

60 x 55 x 3

OCB-010

10

9

11

120 x 110 x 3

OCB-020

20

9

11

240 x 220 x 3

Select the Calibration Board Model

3D Camera Calibration

Selecting a proper calibration board can improve the accuracy and stability of calibration. In actual projects, select the proper calibration board according to the camera model and the actual working distance.

To determine the camera model, please refer to How to Read Camera Serial Number. If you still cannot determine the camera model, contact Mech-Mind Technical Support.

Camera model Working distance (mm) Recommended model

UHP-140-GL

300±20

OCB-005

NANO-GL

300–600

CGB-020

NANO ULTRA-GL

250–500

CGB-020

PRO S-GL

500–800

CGB-020

800–1000

CGB-035

PRO M-GL

1000–1500

CGB-035

1500–2000

CGB-050

LSR S-GL

500–1000

CGB-035

1000–1500

CGB-050

LSR L-GL

1200–3000

CGB-050

DEEP-GL

1200–3500

CGB-050

PRO XS-GL

300–600

CGB-020

Log S

500–800

CGB-020

800–1000

CGB-035

Log M

1000–1500

CGB-035

1500–2000

CGB-050

Laser L Enhanced

1500–3000

CGB-050

2D Camera Calibration

When performing 2D camera calibration, selecting a proper calibration board can improve the accuracy and stability of calibration. In actual projects, select the proper calibration board according to the 2D camera calibration task and camera field of view. If you still cannot determine the camera model, contact Mech-Mind Technical Support.

  1. Determine the 2D camera calibration task type.

    Determine whether the calibration task is distortion calibration or hand-eye calibration according to actual requirements.

  2. Estimate the calibration board dimensions.

    Acquire an image at the target working distance, estimate the calibration board dimensions according to the following requirements, and select a proper calibration board model.

    Calibration type Description Illustration

    Distortion calibration

    It is recommended that the calibration board cover as much of the camera field of view as possible, so that distortion parameters can be calculated stably.

    If the calibration board cannot fit entirely within the field of view, use a smaller calibration board first.

    select board dist

    Hand-eye calibration

    It is recommended to use the OCB-005 model calibration board.

    It is recommended that the calibration board occupy about 1/9 of the field of view in the image (about 8% to 15%), so that feature points can be recognized stably.

    If the calibration board is too small and results in insufficient feature points, use a larger calibration board.

    select board extri

  1. How can users obtain calibration boards?

    Mech-Mind provides standard calibration board models. Users can contact Mech-Mind Sales to obtain them.

  2. Can users print calibration boards by themselves?

    If the project has low accuracy requirements, users can print calibration boards by themselves. However, note that paper deformation, printing scale errors, and surface reflection of printed calibration boards will affect calibration accuracy.

  3. Is it mandatory to use checkerboard calibration boards?

    The standard calibration board models provided by Mech-Mind are circle grid calibration boards. Users can use circle grid calibration boards or checkerboard calibration boards according to actual requirements.

  4. Is it mandatory to use a calibration board for 2D camera hand-eye calibration?

    If it is inconvenient to use a calibration board on-site (limited space or unable to install), markers can be used. However, note that the markers must have clear feature points, and the spatial distribution of the feature points should be as uniform as possible.

  5. Is it necessary to perform distortion calibration before 2D camera hand-eye calibration?

    If the project has high accuracy requirements, it is recommended to perform distortion calibration first, followed by hand-eye calibration, to ensure the accuracy of the hand-eye calibration results.

Mount the Calibration Board

In the following calibration scenarios, you can mount the calibration board on the last joint of the robot.

  • Automatic Calibration in the Eye to Hand (ETH) Scenario

  • Manual Calibration in the ETH Scenario (Multiple Random Calibration Board Poses)

For other calibration scenarios and intrinsic parameter checks, there is no need to mount the calibration board. Please place the calibration board in the center of the object plane.

The calibration board can be mounted on the robot end in two ways, as shown below:

Direct mounting Mounting through robot flange

mount calib board

mount flange

If you use a robot flange to mount the calibration board, you need to purchase a proper model of calibration board from Mech-Mind. For details, refer to Select Robot Model and Robot Flange Model.

Is this page helpful?

You can give a feedback in any of the following ways:

We Value Your Privacy

We use cookies to provide you with the best possible experience on our website. By continuing to use the site, you acknowledge that you agree to the use of cookies. If you decline, a single cookie will be used to ensure you're not tracked or remembered when you visit this website.

  • Preference
  • I accept
  • I don't accept