Zoom Lens Principal Point Estimation for Rapid 3D Measurement
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Solution Overview
Problem
Existing three-dimensional measurement apparatuses require time-consuming repeated projection and imaging to calculate internal parameters of projection lenses, such as focal length and distortion, which limits their efficiency.
Innovation Solution
The method involves projecting a pattern image onto an object using a zoom lens, estimating the principal point position, and interpolating characteristic values based on initial and final positions of the principal point to estimate the lens characteristics at any position, allowing for efficient measurement without repeated movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If repeated projection and imaging are performed while moving the object or moving one of the projection device and the imaging device to calculate internal parameters, then the measurement precision is improved, but the measurement time increases
Solution Approach 1:
The patent pre-calculates and stores correspondence between principal point positions and lens characteristics (focal length, distortion coefficients) at multiple predetermined positions before actual measurement. During measurement, the system only needs to identify the current principal point position and retrieve the corresponding pre-calculated parameters, eliminating the need for repeated projection-imaging cycles during operation.
Solution Approach 2:
The system performs preliminary calibration to establish a mapping relationship between principal point positions and lens characteristics. This pre-established correspondence table allows rapid parameter retrieval during measurement without requiring real-time repeated projections and imaging operations.
2Reliability
If repeated projection and imaging are performed to obtain lens parameters, then the reliability of measurement is improved, but the productivity decreases
Solution Approach 1:
The patent performs preliminary calibration to establish a mapping relationship between principal point positions and lens characteristics. This pre-established correspondence table allows rapid parameter retrieval during measurement without requiring real-time repeated projections and imaging operations, thereby maintaining reliability while improving productivity.
Solution Approach 2:
The system creates a reference table copying the relationships between principal point positions and lens characteristics from calibration data. During actual measurement, this copied reference information is used directly without needing to recreate the relationships through repeated experiments, thus improving measurement efficiency while maintaining accuracy.
Data Source
AI summary
An estimation method includes projecting a pattern image onto an object via a zoom lens, generating imaging data by capturing the pattern image on the object, estimating, based on the imaging data, a position of a principal point of the zoom lens during the projection of the pattern image, and estimating, based on a first characteristic value representing a characteristic of the zoom lens at time when the principal point of the zoom lens is present in a first position and a second characteristic value representing a characteristic of the zoom lens at time when the principal point of the zoom lens is present in a second position, a characteristic value representing a characteristic of the zoom lens at time when the principal point of the zoom lens is present in the estimated position.