Cylindrical Object Diameter Measurement Using Virtual Reference Plane
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Solution Overview
Problem
Existing methods for measuring the diameter of cylindrical objects, such as reinforcing bars, face challenges in versatility and accuracy, particularly when objects are inclined, leading to measurement errors due to the cylindrical shape not appearing thin in images depending on the viewing angle, and require complex calculations with background markers.
Innovation Solution
An object measurement apparatus and method using a camera with a laser distance meter, angle detection units, and deviation calculation to accurately measure the diameter of cylindrical objects by correcting distances and angles, allowing for high accuracy without the need for special measurement jigs or markers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If photogrammetry method with dedicated measurement jig is used, then measurement can be performed, but versatility is low due to requirement of including measurement jig in image
Solution Approach 1:
The patent extracts the measurement reference function from a physical measurement jig and replaces it with a virtual reference plane defined by coordinate information. This eliminates the need for a dedicated measurement jig in the image while maintaining measurement capability, thereby improving versatility.
Solution Approach 2:
The patent introduces coordinate information of a reference plane as an intermediary element between the camera and the measurement target. This virtual reference serves the same function as a physical measurement jig but without the constraints of being visible in the image, resolving the contradiction between versatility and device complexity.
2Measurement precision
If reinforcing bar is corrected on basis of imaging angle like plane, then measurement is performed, but measured diameter is greater than actual diameter due to cylindrical shape
Solution Approach 1:
The patent applies different correction approaches for different object types: plane objects use standard angular correction, while cylindrical objects use a specialized correction method based on their curvature characteristics. This local differentiation resolves the measurement accuracy issue without unnecessarily complicating the overall measurement process.
Solution Approach 2:
The patent changes the correction parameters specifically for cylindrical objects by considering their curvature radius and viewing angle relationships differently from plane objects. This parameter adjustment ensures accurate diameter measurement of cylindrical objects while maintaining simplicity of operation.
3Measurement precision
If background bar with marker is provided behind reinforcing bar, then diameter can be calculated, but calculation becomes complicated requiring triangle area and perimeter calculations
Solution Approach 1:
The patent replaces the complex geometric calculation method (triangle area and perimeter) with a simplified computational approach using coordinate information and projection geometry. This substitution maintains measurement accuracy while dramatically reducing calculation complexity.
Solution Approach 2:
The patent uses coordinate information as a virtual copy of the reference plane, eliminating the need for physical background markers. This virtual copying approach simplifies both the measurement setup and the subsequent calculations while preserving measurement accuracy.
4Measurement precision
If cylinder is captured inclined, then image is obtained, but diameter measurement is inaccurate because cylinder does not appear thin depending on viewing angle
Solution Approach 1:
The patent transitions from two-dimensional image plane measurements to three-dimensional coordinate-based measurements by incorporating depth information through coordinate transformation. This dimensional elevation allows accurate diameter measurement of inclined cylindrical objects by accounting for viewing angle effects in 3D space.
Solution Approach 2:
The patent combines multiple measurement parameters (coordinate information, focal length, object distance, viewing angle) into a composite measurement model. This composite approach integrates various factors to accurately determine cylindrical object dimensions despite inclined viewing angles, resolving the measurement difficulty.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-accuracy and versatile measurement of cylindrical object diameters and spaces between them, correcting for viewing angle errors and simplifying calculations, without the need for complex setups or markers.
Implementation Method 1
a distance acquisition unit that acquires a first distance between the camera and a measurement reference member
Data Source
AI summary
A first angle α formed between a direction normal to a white board (100) that is disposed along a plurality of reinforcing bars (2) and an imaging direction of a camera (200) and a second angle β indicating the direction of the reinforcing bar 2 which is a measurement target with respect to the imaging direction of the camera (200) are detected. In addition, a first distance D1 between the camera (200) and the white board (100) is measured by a laser distance meter provided in the camera (200). The amount of deviation D2 of the reinforcing bar (2) in the imaging direction of the camera (200) with respect to the first distance D1 is calculated on the basis of the measured first distance D1, the detected first angle α, and the detected second angle β.