Position Measurement of Reflective Surfaces Using Virtual Marker Images
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Solution Overview
Problem
Existing methods for measuring the position of objects with reflective surfaces in three-dimensional space face challenges due to large differences in light intensity between specularly and diffusely reflected light, requiring special light sources and wide dynamic-range cameras, which are costly and energy-intensive, and do not provide stable measurements.
Innovation Solution
A position measurement apparatus that uses a camera, a marker object with feature points, and iterative calculation to determine the position of the reflective surface without a special light source or wide dynamic-range camera, by extracting feature points from the captured image and calculating the position based on capturing conditions, model data, and feature point data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If special light sources and wide dynamic-range cameras are used to measure reflective surfaces, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a marker object that creates a virtual image (copy) of itself in the reflective surface. By detecting the position of this virtual image and comparing it with the known actual position of the marker, the system can calculate the reflective surface position without needing special light sources or wide dynamic-range cameras. This copying approach transforms the measurement problem into a geometric calculation problem.
Solution Approach 2:
The marker object serves as an intermediary element between the camera and the reflective surface. Instead of directly measuring the reflective surface which causes light intensity problems, the system measures the marker's virtual image in the reflection, which provides stable detection points for calculation.
2Reliability
If special light sources are used to illuminate reflective surfaces, then measurement reliability is improved, but energy consumption increases
Solution Approach 1:
The system uses ambient light to illuminate the marker object, which then reflects off the target surface to create the virtual image. The marker object essentially serves itself by using available environmental light rather than requiring an external special light source, thereby reducing energy consumption while maintaining measurement reliability through the geometric calculation method.
3Measurement precision
If wide dynamic-range cameras are used to capture reflected light, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
By using the marker's virtual image as a copy, the system can detect positions using standard camera capabilities. The virtual image provides sufficient contrast and detectable features that don't require wide dynamic-range cameras, as the measurement is based on geometric relationships rather than direct reflection intensity measurement.
Solution Approach 2:
The patent replaces the need for complex camera systems with a computational geometry approach. Instead of relying on advanced camera hardware to handle dynamic range issues, the system uses mathematical calculations based on marker positions and virtual image positions to determine reflective surface location, substituting hardware complexity with algorithmic processing.
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 stable measurement of reflective surfaces in three-dimensional space without the need for special light sources or wide dynamic-range cameras, reducing costs and energy consumption while maintaining precision.
Implementation Method 1
a camera (1) that captures a target object (21) having a reflective surface (22) to obtain image data including at least a part of the reflective surface (22), in which a marker object (2) having a plurality of feature points is fixed at a predetermined position with respect to the camera (1) and a mirror image of the camera (1) and the marker object (2) are reflected
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A storage device stores capturing conditions containing a viewpoint position and a shooting direction of the camera (1), model data containing a shape of a segmented mirror, and feature point data representing a positional relationship among a viewpoint position and feature points. A camera (1) captures the segmented mirror having a reflective surface to obtain a captured image containing at least a part of the reflective surface. A marker object (2) has feature points, and is fixed at a predetermined position with respect to the camera (1). A feature-point extracting unit (11) extracts multiple feature points from a captured image when the feature points are reflected in the reflective surface, and determines positions of the feature points within the captured image. A position measuring unit (12) calculates a position of the segmented mirror, based on the capturing conditions, the model data, the feature point data, and the positions of the feature points within the captured image.