3D Shape Measuring Apparatus Using Spatial Fringe Analysis
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Solution Overview
Problem
Conventional three-dimensional shape measuring methods using line sensors face challenges such as complex sensor arrangement, increased noise, and decreased measurement accuracy due to the need for multiple sensors and prolonged imaging times, especially when using temporal fringe analysis or stereo methods.
Innovation Solution
A three-dimensional shape measuring apparatus utilizing a line sensor to read an optical pattern with periodically changing brightness, where the phase of the optical pattern is analyzed based on pixel brightness values and neighboring pixels, allowing for computation of height information using spatial fringe analysis, thereby simplifying sensor arrangement and improving measurement speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple line sensors are used to measure the three-dimensional shape, then the measurement coverage is improved, but the device complexity and noise increase
Solution Approach 1:
The patent divides the measurement task into two sequential stages: first capturing the optical pattern with a single line sensor, then mechanically moving the sensor to capture additional regions. This segmentation of the measurement process in time and space allows comprehensive coverage while maintaining a simple single-sensor configuration, avoiding the complexity of simultaneous multi-sensor arrangements
Solution Approach 2:
The patent extends the measurement capability from a single line to a two-dimensional area by introducing temporal dimension through sequential imaging. The line sensor captures one line at a time, then moves to capture adjacent lines, building up a complete area measurement through time-based accumulation rather than spatial parallelism
2Area of stationary object
If multiple line sensors are used for three-dimensional shape measurement, then the measurement coverage is improved, but the measurement accuracy decreases due to increased noise
Solution Approach 1:
By segmenting the measurement into sequential single-line captures rather than simultaneous multi-line captures, each measurement point is obtained with high signal-to-noise ratio from a single sensor, avoiding the noise accumulation that would occur with multiple sensors
Solution Approach 2:
The patent uses a single line sensor to effectively 'copy' the measurement function across multiple positions through mechanical movement, achieving the coverage of multiple sensors while maintaining the measurement quality of a single high-performance sensor at each position
3Area of stationary object
If temporal fringe analysis method is used with line sensor, then the measurement coverage is improved, but the imaging time is lengthened
Solution Approach 1:
The patent implements continuous measurement by mechanically moving the line sensor between captures without interrupting the overall measurement process. The sensor moves quickly to the next position and immediately captures the next line, maintaining continuous useful action throughout the measurement sequence rather than having idle periods between discrete measurements
4Device complexity
If a single line sensor is used for three-dimensional shape measurement, then the device complexity is reduced, but the measurement coverage is limited
Solution Approach 1:
The patent transforms the static single-line sensor into a dynamic measurement system by introducing mechanical movement. The sensor dynamically repositions itself to capture different lines sequentially, converting a limited static coverage into comprehensive dynamic coverage while maintaining structural simplicity
Solution Approach 2:
The patent adds the temporal dimension to the measurement process, using sequential captures over time to build up area coverage from single-line measurements. This transforms a one-dimensional spatial limitation into a two-dimensional spatial capability through time-based accumulation
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 rapid and accurate measurement of three-dimensional shapes with high resolution using a single line sensor, reducing the need for multiple sensors and minimizing imaging time, while maintaining high measurement accuracy and simplifying the apparatus configuration.
Implementation Method 1
a line sensor which reads the optical pattern, projected onto the target object, as an image
Implementation Method 2
These methods are based on the principle of triangulation. Among others, for the fringe analysis method, there are proposed many techniques such as spatial fringe analysis and temporal fringe analysis
Data Source
AI summary
An apparatus, method, and program for measuring the three-dimensional shape of an object by analyzing an optical pattern projected onto the object includes a line sensor and an image analysis unit. The line sensor reads the target object, onto which the optical pattern is projected. The image analysis unit analyzes the optical pattern in the image read by the line sensor based on a spatial fringe analysis method, and the image analysis unit computes the three-dimensional shape information on the target object. The phase of a pixel included in an image taken of the optical pattern is determined based on the brightness values of the pixel and at least one neighboring pixel in the image; thus the height information of the object can be determined. In addition, the height of the target object at a given position can be computed based on how much the phase of the optical pattern projected onto a certain position of the object is shifted from a reference phase.