3D Line Scan Camera Calibration

Operator Function

Perform pairwise calibration of cameras, output calibration matrices and calibration files. After capturing images of a specified calibration block using line scan cameras, select points on reference and target images respectively. Calculate calibration matrices between cameras based on the point selection results.

Parameter Introduction

Input Parameters

Parameter	Range	Default Value	Description	Illustration
Input Reference Image	0-8	0	Reference image input IM number
Input Target Image	0-8	1	Target image input IM number

Calculation Parameters

Parameter	Range	Default Value	Description	Illustration
Point Selection Mode	Manual/Automatic	Manual	In manual mode, points need to be selected manually, and selection positions must match preset positions on the calibration block. At least 5 non-coplanar point pairs are required, selection range includes vertices of the frustum and 4 vertices of the base upper surface; in automatic mode, input images containing only the calibration block are required, and the calibration block image must be complete. The algorithm will automatically calculate the 8 vertices of the frustum.
Point Selection List			Only displayed in manual mode. Points A-L correspond to vertex positions on the calibration block as shown in the illustration.
Output Calibration File Path		Empty	Calibration file save path
Output Image	0-8	0	The IM number for image output. Displayed images are transformed target image and reference image

Output Parameters

Name	Type	Range	Description
Result	bool	true/false	true for success false for failure
Warning	bool	true/false	true indicates there is a warning false indicates there is none
Message	string		Outputs success, error, or warning information; if there is no error or warning, it is empty
Time	float		Operator execution time, unit: ms
matrix_tgt2ref	matrix		Calibration matrix from target camera coordinate system to reference camera coordinate system.
rms_obj2ref	matrix		Root mean square error between corresponding points on calibration block after transformation and corresponding points on reference image.
rms_obj2tgt	matrix		Root mean square error between corresponding points on calibration block after transformation and corresponding points on target image.
rms_tgt2ref	matrix		Root mean square error between corresponding points on target image after transformation and corresponding points on reference image.

Exception Troubleshooting

No.	Exception Information	Corresponding Parameter	Solution
1	Input image is empty		Check if input image is empty
2	Calibration file path parameter is empty		Select correct file path
3	At least 3 points required for matrix calculation		Set at least 3 points
4	Point pair count mismatch		Number of points set on reference image must equal number set on target image

Example Introduction

This example calculates calibration matrices from target camera coordinate system to reference camera coordinate system through manual point selection mode and automatic point selection mode respectively.

Engineering Design

Manual Point Selection Mode

1. Select 3 Load 3D Point Cloud operators.
2. Select Lua Script operator.
3. Select 2 3D Line Scan Camera Calibration operators.

Automatic Point Selection Mode

1. Select 3 Load 3D Point Cloud operators.
2. Select 2 3D Line Scan Camera Calibration operators.

Tool Usage

Manual Point Selection Mode

1. Select 3 Load 3D Point Cloud operators. Input calibration block images captured by 3 cameras into IM0, IM1, IM2 respectively in order.

2. Select Lua Script operator, input corresponding point coordinates in camera 1, camera 2, and camera 3 images in the script, as follows:

   println('Hello AI-Vision!')
   
   -- Points on camera 1
   SetPoint3D("1_C", 15.5,63.0799980164,-5.95093011856)
   SetPoint3D("1_D", 45.4799995422,63.3099975586,-5.33064985275)
   SetPoint3D("1_E", 28.8999996185,48.1399993896,4.03621006012)
   SetPoint3D("1_F", 38.3799972534,48.1299972534,4.19015979767)
   SetPoint3D("1_G", 28.7799987793,37.969997406,4.01133012772)
   SetPoint3D("1_H", 38.6399993896,38.2599983215,4.21365976334)
   SetPoint3D("1_I", 16.6999988556,3.37999987602,-5.81731987)
   SetPoint3D("1_J", 46.5799980164,3.42999982834,-5.53338003159)
   
   -- Points on camera 2
   SetPoint3D("2_C", 6.33999967575,62.3099975586,-6.11768007278)
   SetPoint3D("2_D", 36.5,62.8599967957,-5.6080198288)
   SetPoint3D("2_E", 19.9200000763,47.6499977112,3.81477999687)
   SetPoint3D("2_F", 29.4200000763,47.3999977112,3.99586009979)
   SetPoint3D("2_G", 19.7799987793,37.6899986267,3.84138989449)
   SetPoint3D("2_H", 29.5999984741,37.8999977112,3.98522996902)
   SetPoint3D("2_I", 7.57999992371,2.72000002861,-6.00668001175)
   SetPoint3D("2_J", 37.3199996948,3.07999992371,-5.76390981674)
   
   -- Points on camera 3
   SetPoint3D("3_D", 24.98, 62.549999, -5.75619)
   SetPoint3D("3_E", 8.44, 47.32, 3.68806)
   SetPoint3D("3_F", 17.9, 47.16, 3.86188)
   SetPoint3D("3_G", 8.26, 37.309998, 3.6232)
   SetPoint3D("3_H", 18.119999, 37.649998, 3.8217)
   SetPoint3D("3_J", 25.959999, 2.84, -5.93972)

3. Select one 3D Line Scan Camera Calibration operator to calibrate between camera 1 and camera 2. Set both reference image point selection and target image point selection to manual mode. Bind 1_C to 1_J in reference image point selection list and 2_C to 2_J in target image point selection list. Set output calibration file path to ./calib_21.json. Set output image number to 3.

4. Select one 3D Line Scan Camera Calibration operator to calibrate between camera 2 and camera 3. Set both reference image point selection and target image point selection to manual mode. Bind 2_D, 2_E, 2_F, 2_G, 2_H, 2_J in reference image point selection list and 3_D, 3_E, 3_F, 3_G, 3_H, 3_J in target image point selection list. Set output calibration file path to ./calib_32.json. Set output image number to 4.

Automatic Point Selection Mode

1. Select 3 Load 3D Point Cloud operators. Input calibration block images captured by 3 cameras into IM0, IM1, IM2 respectively in order.
2. Select one 3D Line Scan Camera Calibration operator to calibrate between camera 1 and camera 2. Set both reference image point selection and target image point selection to automatic mode. Set output calibration file path to ./calib_21.json. Set output image number to 3.
3. Select one 3D Line Scan Camera Calibration operator to calibrate between camera 2 and camera 3. Set both reference image point selection and target image point selection to manual mode. Set output calibration file path to ./calib_32.json. Set output image number to 4.