Camera Calibration

## Camera Calibration

Calculates the correspondence between the image coordinate system and the mechanical coordinate system, and generates a calibration file.

## Module Principle

By selecting the movement coordinates of the robot arm and inputting the image coordinates corresponding to the robot arm movement, the calibration relationship between the image pixel coordinates and the real-world coordinates is established and saved in the global variables.

![](/media/202603/2026-03-12_151839_6054660.8935150023093857.png)

The Camera Calibration module generates mechanical point data through the selected mechanical model, and the image point data is acquired externally (usually by acquiring feature points through Optimized Feature Matching).
The mechanical center pose is the center coordinate of the machine during calibration (the fifth point or the second point). The calibrated mechanical point is calculated and output through this center coordinate and the mechanical type. Therefore, after modifying the mechanical type, you need to click [Mechanical Parameters] to regenerate the mechanical point data once.
Calibration is divided into types with angle R and without angle. For calibration types without angle (XY, X, Y), the relative relationship is calculated, and only the conversion between the input image point and the mechanical point is calculated; for calibration types with angle (XYR, XR, YR), through the final rotation movement of the calibration, the **Rotation Center** of the robot arm is calculated, thereby calculating the absolute conversion relationship between the rotation center on the image and the mechanical coordinates. Since the rotation center is calculated from the feature points captured by the camera, slight errors will be generated due to shooting shake, inaccurate input image points, etc. When the **Rotation Angle** is too small and the **Rotation Radius** is too long, the error will be amplified. Therefore, when calculating calibration with angle, try to move a large angle (more than 30°) and reduce the rotation radius when selecting feature points.

![](/media/202601/2026-01-15_102455_3221300.7217366519004879.png)

Verification is to calculate multiple mechanical point movements again after the calibration is successfully generated to determine whether the calculated rotation center is accurate. Further reduce the error of the calibration **Rotation Center**.

![](/media/202603/2026-03-12_151901_0833920.9022280759459181.png)

The photographing method refers to the relationship between the robot arm and the camera during calibration.
<Eye-in-Hand> The camera moves with the robot arm, and the movement direction of the acquired image points will be opposite to the actual robot arm running direction.
<Eye-to-Hand> The camera is fixed and the robot arm moves, and the movement direction of the acquired image points will be the same as the actual robot arm running direction.

## Usage Scenarios
Performed before picking or alignment calculation. Visual calibration is the process of determining parameters such as camera intrinsics, extrinsics, and lens distortion through image data collected by the camera. The purpose is to establish a precise mapping relationship between image pixel coordinates and actual physical coordinates.

### Pre/Post-Sequence Modules

Camera image acquisition, Optimized Feature Matching to acquire image point data, run multiple times to generate calibration. The output of Camera Calibration is the mechanical point that needs to be reached next time.

![](/media/202603/2026-03-12_151928_6207510.9610406910850667.png)

## Parameter Configuration Description
【Mechanical Parameters】 Set the coordinates of mechanical movement, and obtain image coordinates through input images.
Note: In calibration mode, the first picture taken is not included in the calculation; in simulation mode, the first photo will be used as the first point of the image points.
【Calibration Group】 Select the corresponding coordinate system group, and the calibration data will be recorded in the calibration file under this coordinate system group. The coordinate system group must be set in the Coordinate System Calibration in Global Data Management.
【Calibration File】 Select the calibration file under the corresponding coordinate system group, and the calibration data will be recorded in this file. (The calibration file must be set in the Coordinate System Calibration in Global Data Management. First add a coordinate system group, then drag the camera and robot to the window under the corresponding coordinate system group, select the connection line to connect the two icons, and the calibration file can be generated)
Running Mode:
【Simulation Model】 Generally used when calibrating with a group of pictures. In this mode, the first photo will be used as the first point of the image points. Also, images will not be saved in simulation mode.
【Calibration Mode】 Calibrate according to actual conditions. (Taking 12-point calibration as an example, when the reference image selects a simulation image, 13 images need to be provided, and the first image is not actually calculated. Simulation mode does not need to provide an extra image)
【Save Image】 Save the reference image.
Mechanical Model:
【XYR】 Mechanical structure XY axes can translate and rotate.
【XY】 Mechanical structure XY axes can translate, but cannot rotate or do not need to rotate.
【XR (Y Separated)】 Mechanical structure only has X-axis translation and can rotate, Y-axis structure is separated.
【YR (X Separated)】 Mechanical structure only has Y-axis translation and can rotate, X-axis structure is separated.
【X (Y Separated)】 Mechanical structure only has X-axis translation, Y-axis structure is separated.
【Y (X Separated)】 Mechanical structure only has Y-axis translation, X-axis structure is separated.
Photographing Method:
【Eye-to-Hand】 The camera is installed in a fixed position and does not shift or rotate with the machine.
【Eye-in-Hand】 The camera is fixedly installed on the mechanical rotation axis and shifts and rotates with the machine.
### Mechanical Parameters

Mechanical Movement Settings:
【Translation Row (Column) Count】 Set the number of rows/columns for calibration mechanical movement.
【Rotation Count】 Set the number of rotations for calibration mechanical movement.
【Coordinate System Type】 Determine the coordinate system type of the robot arm.
【Pose Step】 The distance of single movement or rotation during mechanical calibration.
【Center Pose】 The mechanical pose of the center point during translation and rotation in calibration. When subscribe is selected, the value can be referenced in the port as the center pose.
Calibration Judgment:
【Max Displacement Error】 The maximum error threshold between calibration data and calculation data on the mechanical axis.
【Max Angle Error】 The maximum error threshold between calibration data and calculation data angle.
【Center X/Y Compensation】 Offset compensation of the center pose, generally default to 0.
Whether to Enable Verification:
After enabling verification, the calibration will take a few more steps after completion to verify the calibration rotation center. And regenerate the calibration save after verification.
【Verification Max Error】 If verification is enabled, the maximum deviation allowed for the rotation center calculation. If the calculation deviation exceeds the verification maximum error, the rotation center calculation deviation is compensated, and the calibration data is regenerated.
【Detection Angle】 The rotation angle step of the mechanical axis during the verification process.
【Detection Count】 The number of times to perform verification.
【Center Compensation】 Offset compensation of the center pose, adding the center deviation calculated by verification as a compensation value to the center pose.
【Movement Data】 The mechanical movement data corresponding to the mechanical calibration.
【Confirm】 Save the mechanical parameters. Be sure to click Confirm to save after setting the mechanical parameters, otherwise the set values will be restored to default values!

## Output Description

![](/media/202603/2026-03-12_152022_8450840.7372480906784388.png)
The total run result outputs true after the calibration is successful, otherwise false.
The single run result outputs the run result of each photographing movement.
When calibration generation fails, both the total run result and the single output are false.
## Precautions

1. When using a bottom camera, X-axis mirroring is required.
2. For calibration with angle R, the rotation angle is best to be above 30° to improve the calculation accuracy of the rotation center.
3. Too long rotation radius will affect alignment accuracy.
4. The height of the plane for calibration needs to be the same as the height during use, otherwise there will be errors.
5. After modifying the mechanical model of a single camera, you need to click Mechanical Parameters to regenerate the calibration data.
6. In normal mode (calibration mode), the first image of camera calibration is not included in the calculation, and the camera needs to take one more photo to complete the calibration.
## Problem Solving
Build the following flow to test the accuracy of the calibration in xy directions. Move the matching object 1-10mm, observe whether the calibration conversion result changes correspondingly to test the accuracy.

![](/media/202603/2026-03-12_152203_6181840.08111837465297045.png)
During alignment or picking, when the offset angle increases, causing the xy error to increase correspondingly, it is a calculation error of the calibration rotation center. You can solve the problem by increasing the calibration angle movement (more than 30 degrees). Or by checking calibration verification, using long radius calibration, etc.

[【Attachment】Camera Calibration Example Project.rar](/media/attachment/2026/03/%E7%9B%B8%E6%9C%BA%E6%A0%87%E5%AE%9A%E7%A4%BA%E4%BE%8B%E5%B7%A5%E7%A8%8B.rar)

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Click here to jump to the corresponding Chinese manual page: [Camera Calibration](/doc/125)