Sheet of Light Detection via Second Derivative Zero-Crossing
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Solution Overview
Problem
Existing methods for detecting the position of a sheet of light in 3D measurement and reconstruction systems are sensitive to background intensity variations and lack robustness, especially when dealing with varying sheet widths and peak shapes, requiring multiple parameters and being computationally inefficient.
Innovation Solution
The method employs a second derivative filter to analyze the intensity profile of a sheet of light, determining ingress and egress pixel positions based on zero-crossing second derivative values, and calculates the midpoint position as the sheet's location, enabling accurate detection across varying scenarios with a single set of parameters and efficient computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods are used to detect sheet of light position, then the detection can be performed with simple algorithms, but the detection accuracy deteriorates due to sensitivity to background intensity variations and inability to handle varying sheet widths
Solution Approach 1:
The patent transforms the detection approach by changing the parameter being analyzed from raw intensity values to the second derivative of intensity values. This parameter transformation makes the detection invariant to background intensity variations and sheet width changes, resolving the contradiction between improved accuracy and increased complexity by using a mathematically robust parameter that inherently compensates for these variations.
Solution Approach 2:
The patent replaces traditional mechanical/image-processing approaches (thresholding, peak detection) with a mathematical derivative-based approach. By substituting the detection mechanism with second derivative analysis, the system achieves higher precision without requiring complex multi-parameter algorithms, as the second derivative inherently highlights the sheet boundaries regardless of intensity variations.
2Adaptability or versatility
If multiple parameters are used to detect sheet of light position, then the detection can adapt to varying sheet widths and peak shapes, but the computational efficiency deteriorates
Solution Approach 1:
The second derivative operation serves multiple functions simultaneously: it detects sheet boundaries, determines ingress and egress points, and provides adaptability to varying sheet widths and peak shapes. This single mathematical operation replaces what would traditionally require multiple separate parameters and algorithms, achieving universality that maintains both adaptability and computational efficiency.
Solution Approach 2:
By changing from intensity-based parameters to second derivative-based parameters, the system achieves universal adaptability across different sheet widths and peak shapes. The second derivative parameter inherently normalizes these variations, allowing a single detection algorithm to handle diverse conditions without requiring multiple adaptive parameters, thus maintaining computational efficiency.
3Reliability
If traditional detection methods are used, then the computation is faster with simpler algorithms, but the reliability deteriorates due to sensitivity to background variations
Solution Approach 1:
The patent achieves robustness by changing the detection parameter from raw intensity to second derivative of intensity. This parameter change inherently compensates for background intensity variations and sheet width changes, providing reliable detection across varying conditions. The increased algorithmic complexity is minimal (applying a second derivative filter) compared to the substantial gain in reliability.
Data Source
AI summary
A method for detecting a position of a sheet of light is described. A second derivative filter is applied to an intensity profile of a line of pixels. An ingress pixel position associated with an ingress zero-crossing second derivative value is determined. The ingress pixel position is between a first pixel position with a first minimum intensity value of the intensity profile and a second pixel position with a first maximum intensity value of the intensity profile. An egress pixel position associated with an egress zero-crossing second derivative value is determined. The egress pixel position is between a third pixel position with a second maximum intensity value of the intensity profile and a fourth pixel position with a second minimum intensity value of the intensity profile. A midpoint pixel position between the ingress pixel position and the egress pixel position is output as the position of the sheet of light.