Portable 3D Scanner Using Epipolar Geometry for Smooth Surface Scanning
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Solution Overview
Problem
Existing portable scanners face challenges in generating accurate 3D scans of objects with smooth surfaces and few features, as they struggle with scattered light and require stationary devices for pattern projection and image capture, limiting their applicability and accuracy.
Innovation Solution
A portable 3D measurement device equipped with a projector, two cameras, and a control and evaluation unit that uses epipolar geometry to determine 3D coordinates, allowing for dynamic scanning and auto-calibration, enabling efficient 3D scanning of objects with minimal features and smooth surfaces by projecting an uncoded light pattern and capturing images with overlapping fields of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a stationary device is used for pattern projection and image capture, then measurement precision is improved, but device portability and adaptability deteriorate
Solution Approach 1:
The patent combines the projector and two cameras into a single integrated portable device, merging previously separate stationary components into one unified system that maintains measurement precision while enabling portability and dynamic scanning applications
Solution Approach 2:
The invention transitions from stationary to dynamic scanning by enabling the portable device to move during operation, with the control and evaluation unit processing images captured at different positions and times to reconstruct accurate 3D coordinates of stationary objects
2Device complexity
If an uncoded light pattern is projected, then device complexity is reduced, but measurement precision deteriorates due to scattered light on smooth surfaces
Solution Approach 1:
The patent introduces a diffractive optical element as an intermediary component in the projector that structurally encodes the light pattern without requiring complex electronic encoding, maintaining measurement precision through optical diffraction while keeping the device relatively simple
Solution Approach 2:
The invention changes the optical parameters of the light pattern through diffraction, creating a structured pattern that provides sufficient contrast and feature information for accurate 3D measurement on smooth surfaces without requiring complex coded patterns
3Measurement precision
If two cameras with overlapping fields of view are used, then measurement precision is improved through epipolar geometry, but device complexity increases
Solution Approach 1:
The patent uses two cameras with overlapping fields of view to capture images from different perspectives, utilizing epipolar geometry to determine 3D coordinates by triangulation, thereby adding a spatial dimension to the measurement process and improving accuracy
Solution Approach 2:
The invention replaces complex mechanical measurement systems with an optical-based epipolar geometry approach, using light reflection and image processing to determine 3D coordinates, thereby reducing mechanical complexity while maintaining or improving measurement precision
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 high-resolution, dynamic 3D scanning of objects with smooth surfaces and few features, improving scanning accuracy and efficiency by using epipolar geometry for precise coordinate determination and auto-calibration, making the device suitable for various applications beyond stationary use.
Implementation Method 1
emitting a light pattern onto an object with the projector
Implementation Method 2
recording a first image of the light pattern with the first camera
Data Source
AI summary
A method for scanning and obtaining three-dimensional (3D) coordinates is provided. The method includes providing a 3D measuring device having a projector, a first camera and a second camera. The method records images of a light pattern emitted by the projector onto an object. A deviation in a measured parameter from an expected parameter is determined. The calibration of the 3D measuring device may be changed when the deviation is outside of a predetermined threshold.