🟠 Point Cloud Align to Line

Function Description

This operator is used to align input point clouds to specified mathematical lines. It traverses each input point cloud and each line model, filters out point cloud points close enough to the line based on the set "line thickness" parameter, then precisely projects these points onto that mathematical line, finally generating one or more line point clouds composed of these projected points.

Usage Scenarios

  • Line feature refinement: After detecting one or more lines through operators like "RANSAC Fitting", the input point cloud (such as object edge points) may still have certain thickness or noise. This operator can precisely align these rough edge points to the fitted ideal line, obtaining clean, standard line features.

  • Data filtering and extraction: Extract only points belonging to a line from a complex point cloud based on known line positions.

  • Measurement preprocessing: Before performing precise measurements like length and distance, align detected line features to eliminate measurement errors caused by point cloud noise or thickness.

Input Output

Input

Edge Point Cloud: Input point cloud or point cloud list to be aligned, usually edge points of objects.

Line Equation Parameters: Parameter list of one or more line models.

Output

Line Point Cloud: List of point clouds aligned and projected onto input line models. Each output point cloud corresponds to a successfully matched combination of input point cloud and line model.

Parameter Description

This operator has two versions:

  • Point Cloud Align to Line: Processes point clouds without normal information.

  • Point Cloud Align to Line (With Normals): Processes point clouds with normal information.

Both have identical core functions and parameters, differing only in the type of point cloud data processed.

Line Thickness

Parameter Description

Defines a distance threshold used to judge whether a point belongs to a certain line. Only when a point’s perpendicular distance to the line is less than or equal to this value will it be considered part of this line.

Parameter Adjustment

  • Increase this value: Will relax filtering conditions, allowing points relatively far from the ideal line to be included. This is suitable for cases where original point cloud edges are thick, blurry, or have high noise. But if the value is too large, it may incorrectly include unrelated points.

  • Decrease this value: Will tighten filtering conditions, only points very close to the ideal line will be selected. This is suitable for cases where original point cloud edges are clear with low noise, and can obtain more precise results, but may also lose some valid points due to being too strict.

Parameter Range

[0,1000], Default: 10

Minimum Proportion of Line Points

Parameter Description

This is a quality control parameter. For each input point cloud, only when the proportion of points identified as belonging to a certain line to the total points in that input point cloud is greater than or equal to this parameter value will the operator generate the final line point cloud.

Parameter Adjustment

This parameter is used to prevent accidentally generating invalid lines from unrelated noise points.

  • Increase this value: Requires a higher proportion of points to conform to the line model, effectively filtering out occasional "false" lines formed by a few points.

  • Decrease this value: Relaxes this check. When set to 0, line point clouds will be generated as long as any points meet the conditions, without proportion limits.

If you’re confident that the input edge point clouds are mainly composed of lines, this value can be set high (such as above 0.5); if uncertain, it can be appropriately lowered or use the default value.

Parameter Range

[0,1], Default: 0.2