Laser Scanner Shadowing Detection via Convex Hull Projection
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Solution Overview
Problem
In industrial laser scanning of flat-top volumetric objects, shadowing occurs when taller objects occlude laser beams, leading to incorrect size measurements, particularly in mass flow situations, where existing technologies struggle to detect shadowing accurately without additional hardware.
Innovation Solution
The technique involves analyzing the locations of unshadowed points in a 3D point cloud to identify shadowing by projecting points of lower convex hull objects towards higher objects, detecting proximity, and generating a shadowing event indication to alert users, utilizing existing laser scanning devices and processing circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser scanning devices are used to measure dimensions of flat-top volumetric objects in mass flow situations, then productivity is improved, but measurement precision deteriorates due to shadowing by taller objects
Solution Approach 1:
The system performs preliminary shadow detection by projecting convex hulls of lower objects toward higher objects along laser beam propagation directions before final dimension measurement. This preliminary action identifies potential shadowing issues that would affect measurement accuracy, allowing the system to flag or correct measurements before they are finalized.
Solution Approach 2:
The patent introduces convex hull projection as an intermediary computational step between raw laser scan data and final dimension measurements. By projecting the convex hull of each lower object toward higher objects and detecting intersections, the system creates a virtual model of shadow regions that mediates between the physical occlusion problem and the measurement extraction process.
2Measurement precision
If additional laser scanning devices are deployed to eliminate shadowing, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Instead of deploying additional physical laser scanning devices, the system creates a virtual copy of the scanning geometry through convex hull projection. The projection mathematically replicates the laser beam paths and detects where they would be blocked, providing shadow information without requiring duplicate hardware.
Solution Approach 2:
The patent replaces the mechanical solution of adding more physical scanners with a computational approach using convex hull projection and geometric intersection detection. This substitution eliminates the need for additional hardware while achieving the same shadow detection function through mathematical modeling.
3Measurement precision
If customers are responsible for preventing shadowing situations, then measurement precision is maintained, but ease of operation deteriorates
Solution Approach 1:
The system performs self-service by automatically detecting shadowing conditions through convex hull projection without requiring customer intervention. The dimensioner independently analyzes its own scan data, projects convex hulls, detects shadow regions, and flags affected measurements, eliminating the need for customers to manually prevent or identify shadowing situations.
Solution Approach 2:
The patent implements feedback by using detected shadowing information to influence the final measurement output. When shadowing is detected through convex hull intersection, the system provides feedback that affects measurement reporting, allowing customers to take appropriate action while maintaining operational simplicity.
Data Source
AI summary
Disclosed are techniques for detecting presence of shadowing introduced in a system. The techniques entail geometrically projecting, along a virtual or actual propagation direction of laser beam scanning, points of a lower convex hull (CH) planar object in a direction toward a higher CH planar object to establish projection locations of the points of the lower CH planar object along the propagation direction. Detection of whether the projection locations are in proximity to locations of points of the higher CH planar object is performed. In response to detecting locations in proximity for each source laser beam scanning, a shadowing event indication is generated to alert a user of the system that shadowing has been introduced in the system.