3D Cylinder Fitting

Operator Function

Perform cylinder fitting on the input point cloud to obtain the fitted cylinder parameters: top and bottom center coordinates and cylinder radius (for better fitting results in a relatively short time, it is recommended that the point cloud contains 1000-100000 points)

Parameter Introduction

Input Parameters

Parameter	Range	Default Value	Description	Illustration
Input Image	0-8	0	IM number for image input

Calculation Parameters

Parameter	Range	Default Value	Description	Illustration
Region	2D Window/2D Circular Window/2D Polygon Window/Box/Cylindrical Box/Rotated Box/Point Set (binding only)	Box	Manual selection: Set the ROI region for cylinder fitting > Note: Ensure the ROI center point is inside the circle. Can bind to select existing ROI region
Statistical Filter	true/false	false	Apply statistical filtering to the input point cloud
Standard Deviation Multiple Threshold	0.1-10	0.150	Input parameter n, any point exceeding n times the standard deviation from the mean will be considered an outlier and removed
Neighborhood Points	3-500	100	Number of neighbor points to consider during filtering (this number must be less than the number of input point cloud points)
K-Nearest Neighbors	3-500	20	When calculating the normal of a point in the point cloud, the number of surrounding points to search. If the set search number is too large, it may introduce points far from the current point, leading to inaccurate estimation; if the set value is too small, it may ignore some adjacent points, also affecting the accuracy of normal estimation.
Distance Threshold	0-10000	0.15	When the distance between a data point and the fitted model is less than this threshold, the data point is considered an inlier (i.e., a point that fits the model); otherwise, it is considered an outlier (i.e., a point that does not fit the model)
Minimum Points		0	Set the minimum number of points in the input point cloud
Maximum Points		1000000	Set the maximum number of points in the input point cloud

Note: As shown in the figure below, in the spatial coordinate system, a cylinder can be determined by the top and bottom center points and radius R.

Result Display

Parameter	Range	Default Value	Description	Illustration
Cylinder	true/false	false	If enabled, display the cylinder in the image
ROI Point Set	true/false	false	Only effective when Use Region Parameters is selected. Region point set selected by ROI box. If enabled, display in the image

Output Parameters

Name	Type	Range	Description
Result	bool	true/false	true for success false for failure
Warning	bool	true/false	true indicates a warning false indicates no warning
Message	string		Output success, error, or warning messages. Empty if no error or warning.
Time	float		Operator execution time, unit: ms
cylinder	cylinder		Output cylinder

Tip

For more detailed explanations of parameter types, please refer to Type Definitions

Exception Troubleshooting

No.	Exception Information	Corresponding Parameter	Solution
1	Input region type is {0}, invalid region type	Region Type	Region input type must be one of: 2D Window/2D Circular Window/2D Polygon Window/Box/Cylindrical Box/Rotated Box/Point Set
2	Region is empty		1. Check if selection is empty 2. Check if point set is empty
3	Input point cloud is empty		Confirm if IM contains valid points. If no valid points, load point cloud or switch to IM with valid points
4	Filter parameters are invalid		Adjust statistical filter parameters
5	Point limit is invalid		Set the upper limit of point cloud to be less than the actual point cloud size
6	Input point cloud count exceeds limit		Adjust point limit range or replace with point cloud that meets the limit
7	Input polygon vertex count is less than 3, cannot form polygon		Add 2D polygon window vertices so that vertex count is at least three

Example Introduction

Engineering Design

1. Select the Load Point Cloud tool to load the required 3D point cloud image to IM0.

2. Select the 3D Cylinder Fitting tool.

Tool Usage

1. Select the input image for the operation. The image number must match the IM number where the image is located in the project.

2. Select the region type as Box, move the box to the position to be measured, enclosing the point cloud area to be tested.

Usage Tips

1. Use the ROI controller on the image window to drag or scale the box;
2. Directly modify the box's start or end point coordinates in the calculation parameters to adjust the box position and size;

3. Set the parameters.

4. Check the content you want to display in the result display section.

5. Click Test to check if the image window and parameters meet expectations.

6. If there are no issues, click Save. Run the operator in the run list, and then view the running results in the corresponding IM.