Stereo Diameter Measurement Using Adaptive Point Scanning
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Solution Overview
Problem
Existing methods for measuring the diameter of cylindrical objects using parallax images from two viewpoints are prone to errors, especially when the object is inclined, and require complex setups and adjustments, leading to inaccuracies and increased costs.
Innovation Solution
A measuring device and method that includes a parallax image storage, display, outline detector, measurement point designator, corresponding point deriver, and diameter calculator, which uses stereo matching and adaptive straight line detection areas to accurately calculate the diameter of cylindrical objects with high precision, even when the object is not aligned with the parallax direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light beams are applied to three points on the cylindrical object (active method), then measurement can be performed even when the object is inclined, but device size increases and initial setting and adjustment require much time and effort
Solution Approach 1:
The patent extracts and eliminates the need for light beams and active illumination systems by using passive photogrammetry with naturally lit objects. The solution takes out the complex lighting apparatus while retaining the core measurement functionality through image capture and processing alone.
Solution Approach 2:
The patent creates a virtual 3D model (copy) of the cylindrical object from 2D images taken from multiple viewpoints. This digital copy allows for accurate diameter measurement without physical interaction or active lighting, replacing the need for light beam projection with computational geometry.
2Measurement precision
If tangents are drawn to the circumferential surface in viewpoint images, then the diameter can be calculated, but errors easily creep in during tangent drawing and mathematization
Solution Approach 1:
The patent replaces the manual or algorithmic process of drawing and detecting tangents with automated image processing and 3D coordinate transformation. Instead of geometric tangent construction, the system uses vanishing point detection and projective geometry to directly calculate the diameter from corresponding points in multiple views.
Solution Approach 2:
The patent transitions from 2D tangent detection in image planes to 3D spatial reasoning by reconstructing the cylindrical object's geometry in three-dimensional space. By working in 3D coordinates derived from multi-view correspondence, the system avoids the inherent ambiguities of 2D tangent detection.
3Measurement precision
If a plane orthogonal to the central axis is determined from the parallax image, then the diameter can be measured, but errors tend to creep in when the cylindrical object is imaged in a state of being inclined
Solution Approach 1:
The patent introduces dynamic adaptation by automatically detecting the vanishing point and adjusting the measurement plane orientation based on the actual object orientation in the image. Instead of assuming a fixed orthogonal plane, the system dynamically determines the correct measurement plane that accounts for object inclination, thereby maintaining accuracy regardless of object pose.
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
The solution enables precise diameter measurement of cylindrical objects using a simple handheld device like a 3D-capable digital camera, reducing errors and setup complexities, and maintaining accuracy regardless of the object's position relative to the parallax direction.
Implementation Method 1
Taking a viewpoint image of an observation object from each of two viewpoints a fixed distance apart and indicating a specific point situated on the observation object in each of the viewpoint images allow calculation of a distance from an imaging position to the observation object based on the principle of triangulation
Implementation Method 2
measuring device and a measuring method for measuring the diameter of a cylindrical object based on a parallax image obtained by making exposures from two viewpoints
Data Source
AI summary
Imaging a cylindrical object, left and right viewpoint images are stored to a data memory. To calculate a diameter D of the cylindrical object, a pair of measurement points designated on outlines of the left viewpoint image and corresponding points that are set on outlines of the right viewpoint image in accordance with measurement points are used. While one of the measurement points is fixed on the outline, the other measurement point is scanned on the other outline, such that the distance between the pair of measurement points is minimized. The positions of the corresponding points are updated in synchronization with this. Whenever the corresponding points are updated, the diameter D is calculated, and a minimum value of the calculated diameters is determined as the diameter D of the cylindrical object.