I. Background
When welding cameras capture workpieces with complex shapes, they often encounter issues related to multiple reflections. This is especially true for scenarios involving narrow weld seams, weld spots on the seam, highly reflective surfaces, or blind spots in certain areas caused by special shooting angles. In such complex scenarios, more ideal point cloud data can be obtained by appropriately adjusting relevant parameters and changing the shooting angle to improve image acquisition quality, effectively reduce reflection interference, ensure the clarity of workpiece details, and thereby enhance overall inspection accuracy.
The following sections mainly introduce adjustment methods for several typical welding workpieces, such as angle steel weld seams, V-shaped weld seams, and weld seams with oil contamination. For each type of workpiece, the focus is on explaining the specific steps and principles of parameter adjustment and angle adjustment.
II. Welding Workpiece Adjustment - How to Adjust Related Parameters
- For reflective workpieces, it is recommended to select the Reflective Object mode for the projection encoding pattern. Compared with the Precision Mode, this mode can acquire more complete point cloud data, as shown in the figure below:
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In actual operation, the exposure value and gain value of the 3D camera should be reasonably adjusted according to the on-site conditions. For reflective or overly bright scenes, the 3D exposure value and gain value should be appropriately reduced to avoid overexposure; while under overly dark conditions, these two parameters should be appropriately increased to enhance image clarity. For specific adjustments, please refer to Camera Exposure Adjustment: How to Determine Overexposure/Underexposure Using 2D and 3D Images with Mech-Eye Viewer and Third-Party Software Tools. To maintain shooting efficiency, it is not recommended to set an excessively long 3D exposure time. Image brightness can be improved by moderately increasing the gain value to ensure shooting speed while optimizing imaging results.
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For point cloud post-processing, the noise removal can be set to off as needed to retain more details in the point cloud.
III. How Different Types of Welding Workpieces Ensure Point Cloud Integrity Through Angle Adjustment
1. For 90° Three-Side Direct Intersection Right-Angle Welding Workpieces
| 90° Single Right-Angle Carbon Steel | Right-Angle Welding Workpiece |
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Adjustment Approach
First, adjust the relevant parameters according to the content in the section above [Welding Workpiece Adjustment - How to Adjust Related Parameters]. Then, adjust the camera angle to observe the situation at different angles, and ensure that the three weld seams are as complete as possible.
To Ensure the Integrity of Weld Seam Point Cloud Data, Please Adjust the Camera Position According to the Following Steps:
- Adjust the camera to the angular bisector OA of the right-angle weld seam, that is, on the extension line of the 45° angle, as shown in the figure below.
- Using the AOZ plane of the workpiece coordinate system as the baseline, rotate upward and downward along the Z-axis, ensuring that the rotation angle is controlled within the range of 33° to 63°; this range can obtain relatively complete point cloud data.
- Controlling the XOY plane within the attitude range of 36°-45° can achieve high-quality point cloud results.
As shown in the figure below, a coordinate system is established based on the three welding gaps of the angle steel, showing the actual positional relationship between the workpiece and the camera (in actual situations, the angle may vary slightly; the point cloud meeting the requirements shall prevail).
Green Area: The camera movement range in the AOZ plane when the point cloud is good.
Blue Area: The camera movement angle range in the XOY plane when the point cloud is good.
Principle Explanation
The basic principle is the same as that for single weld seam workpieces. It is necessary to consider the integrity of the three sides and minimize the impact of multiple reflections as much as possible.
Effect Display
| Workpiece Type | Welder Seam Perpendicular to Camera Baseline (Missing) | Camera and Weld Seam at Required Angle (Complete) |
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| Workpiece Type | XOY:45°/AOZ:63° | XOY:43°/AOZ:63° | XOY:35°/AOZ:63° |
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XOY:60°/AOZ:48° |
XOY:43°/AOZ:48° |
XOY:20°/AOZ:48° |
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XOY:56°/AOZ:33° |
XOY:44°/AOZ:33° |
XOY:36°/AOZ:33° |
2. Adjustment Approach for Single Weld Seams Such as “V”-Shaped Workpieces, Right-Angle Workpieces, and J-Shaped Workpieces
| V-Shaped Workpiece Weld Seam | Right-Angle Workpiece | J-Shaped Workpiece |
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Parameter Adjustment Conclusions for Different Workpieces
Based on Comprehensive Parameter Adjustment Tests:
- It is not recommended to shoot parallel to the baseline; unify the use of the camera baseline perpendicular to the V-shaped groove for shooting.
- The reflectivity of the workpiece material in the V-shaped weld groove is a direct factor affecting the point cloud effect.
Currently, workpieces are mainly divided into three categories: highly reflective workpieces, moderately reflective workpieces, and low-reflectivity workpieces. Each category corresponds to different gloss levels, as shown in the figure below:
| Different Material V-Shaped Grooves | Gloss Level | Parallel to Camera Baseline | Perpendicular to Camera Baseline | Conclusion |
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| Highly Reflective V-Shaped Groove |
150.4Gu |
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Based on the XOZ plane of the workpiece coordinate system, rotate upward and downward along the Z-axis. When the rotation angle is between 0° and 90°, it is impossible to obtain relatively complete point cloud data, especially on the right side of the groove surface. Even after repeatedly adjusting the exposure parameters, there is still an obvious point cloud missing problem. |
| Moderately Reflective Workpiece |
72.7Gu |
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When the weld seam is perpendicular to the baseline and the XOZ plane rotation angle is between 28° and 70°, the groove surface can be basically completely imaged. |
| Low-Reflectivity Workpiece |
7Gu |
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The weld seam can be completely imaged whether parallel or perpendicular to the baseline. Due to the rough surface of the workpiece material, there are fewer multiple reflections, the imaging effect is better, and the angle requirements are not high. |
Adjustment Approach
For parameter adjustment, follow the content in [Welding Workpiece Adjustment - How to Adjust Related Parameters], and appropriately increase or decrease the 3D exposure value according to the characteristics of the workpiece and the actual situation. After the parameters have been adjusted to a reasonable range, if there are still missing areas, they can be optimized by adjusting the camera angle again. This article mainly focuses on the adjustment of moderately reflective objects.
Angle Adjustment Requirements
During the adjustment process, for reflective material grooves, if the baseline is parallel to the weld seam, the weld seam may be distorted. Therefore, the current adjustment needs to maintain a state where the camera baseline is perpendicular to the weld seam, and then appropriately adjust the camera angle.
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First, ensure that the camera is basically perpendicular to the workpiece weld seam as much as possible, that is, the camera baseline is perpendicular to the OX axis.
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According to the diagram, adjust the camera pitch angle α. For moderately reflective workpieces, controlling the angle within 28°-70° can make the point cloud more complete. (28° < α < 70°). For very highly reflective workpieces, the angle range may need to be appropriately reduced.
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The camera needs to be moved forward and backward to ensure that the workpiece is within the camera’s projection range, avoiding blind spots in the field of view.
As shown in the figure below, a coordinate system is established based on the V-shaped weld seam workpiece:
| Oblique View | Front View | Side View |
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Effect Display
| Workpiece Type | Weld Seam Parallel to Camera Baseline | Weld Seam Perpendicular to Camera Baseline |
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| Welding Workpiece | α Angle 60° | α Angle 50° | α Angle 40° | α Angle 30° | |
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| Moderately Reflective Workpiece |
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Principle Explanation
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When the weld seam is perpendicular to the camera, that is, when the projection fringe direction is parallel to the weld seam, the interference signal only affects the left and right directions. In the point cloud reconstruction process, this state is more conducive to correctly identifying the fringes, thereby ensuring the integrity of the point cloud.
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When the camera has an appropriate pitch angle tilt, it can avoid the projection light reflecting directly back into the camera from the workpiece surface, thereby reducing interference with correct point cloud reconstruction. As shown in the figure below.
3. For Steel Structure Rib Plate Welding Three-Side Direct Intersection Right-Angle Welding Workpieces
| Steel Structure Rib Plate Welding Workpiece | Right-Angle Welding Workpiece |
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Adjustment Approach
First, adjust the relevant parameters according to the content in [Welding Workpiece Adjustment - How to Adjust Related Parameters] mentioned above. Then, adjust the camera angle to observe the situation at different angles, and ensure that as many visible weld seams are complete as possible.
To Ensure the Integrity of Weld Seam Point Cloud Data, Please Adjust the Camera Position According to the Following Steps:
- Adjust the camera to the angular bisector OA of the right-angle weld seam, that is, on the extension line of the 45° angle, as shown in the figure below.
- Using the workpiece coordinate system’s AOZ plane as the baseline, rotate upward and downward along the Z-axis, ensuring that the rotation angle is controlled within the range of 10° to 73°; this range can obtain relatively complete point cloud data.
- Controlling the XOY plane within the attitude range of 43°-63° can achieve high-quality point cloud results.
As shown in the figure below, a coordinate system is established based on the three welding gaps farthest from the camera in the steel structure, showing the actual positional relationship between the workpiece and the camera (in actual situations, the angle may vary slightly; the point cloud meeting the requirements shall prevail).
Green Area: The camera movement range in the AOZ plane when the point cloud is good.
Blue Area: The camera movement angle range in the XOY plane when the point cloud is good.
Summary
In the actual adjustment process, it is recommended to directly adopt the recommended angle of 45° for the AOZ plane, and set the rotation angle of the XOY plane between 43° and 63° as the effective shooting angle range for on-site adjustment.
Principle Explanation
The basic principle is the same as that for single weld seam workpieces. It is necessary to consider the integrity of multiple welding gaps and minimize the impact of multiple reflections as much as possible.
Effect Display
When the camera angle is at AOZ 45°, the overall point cloud effect is better.
| Welding Workpiece | AOZ:10°/XOY:36.4° | AOZ:10°/XOY:51.4° | AOZ:10°/XOY:63.4° | AOZ:45°/XOY:61.4° | |
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AOZ:45°/XOY:11.4° |
AOZ:45°/XOY:21.4° |
AOZ:45°/XOY:45° |
AOZ:45°/XOY:61.4° |
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AOZ:73°/XOY:10.7° |
AOZ:73°/XOY:42.7° |
AOZ:73°/XOY:55.7° |
AOZ:73°/XOY:67.7° |
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4. Point Cloud Adjustment for Weld Seams with Oil Contamination and Weld Spots
Adjustment Approach
In terms of parameter settings, the 3D exposure value should be appropriately increased to enhance the imaging effect for complex surfaces (such as reflective objects or oil-covered areas). At the same time, the shooting angle adjustment can be carried out according to the angle adjustment methods described in Sections 1 and 2 above to ensure the best image quality under different workpiece conditions. This combined optimization helps improve inspection accuracy and effectively reduces shooting blind spots and reflection interference.
Principle Explanation
Since the reflective object mode adopts a multi-line projection method, it has higher requirements for the intensity of the camera’s projection signal. Therefore, the 3D exposure value can be appropriately increased. This can effectively enhance the imaging quality of reflective objects, especially when dealing with complex surfaces such as oil contamination. Increasing the 3D exposure value can improve the capture of image details, thereby better solving imaging difficulties caused by surface gloss or oil contamination.
