Stereo Camera Specular Reflection Artifact Reduction
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Solution Overview
Problem
Stereophotogrammetry systems using a single camera face challenges in accurately reconstructing 3D surfaces due to specular reflections, which cause artefacts and distortions in the reconstructed images, especially on shiny surfaces.
Innovation Solution
The use of two separate light sources, aligned with the dual optics and placed perpendicular to the axis of the optics, creates four virtual positions for the specular point, allowing the algorithm to select the correct correspondence point, reducing artefacts and improving 3D reconstruction accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single camera with dual optics is used for stereophotogrammetry, then device compactness is improved, but specular reflections cause reconstruction artefacts and reduce measurement precision
Solution Approach 1:
The single light source is segmented into two separate light sources (2A, 2B), each aligned with one of the two optics (OA, OB). This segmentation allows the system to create four distinct virtual positions for specular points, enabling the algorithm to correctly identify correspondence points and eliminate reconstruction artefacts caused by specular reflections, thereby improving measurement precision while maintaining device compactness.
2Object-generated harmful factors
If cross polarization is used to reduce specular reflections, then reconstruction artefacts are reduced, but image brightness is significantly reduced
Solution Approach 1:
Instead of using cross-polarization filters that reduce overall image brightness, the invention segments the single light source into two separate light sources aligned with each optic. This approach reduces specular reflection artefacts by creating distinct virtual positions for specular points, allowing correct point correspondence identification, while maintaining adequate image brightness for accurate reconstruction.
3Device complexity
If a single light source is used with dual optics, then device complexity is reduced, but specular spots shift between images causing point identification errors
Solution Approach 1:
The single light source is divided into two separate light sources (2A, 2B), each aligned with one optic (OA, OB) respectively. This segmentation creates four virtual positions for specular points in the stereo pair, enabling the algorithm to correctly identify point correspondences and eliminate identification errors, thereby improving measurement precision while only moderately increasing device complexity.
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
This approach effectively reduces surface reconstruction artefacts linked to specular reflections, enabling accurate 3D surface reconstruction on various surfaces, including convex and concave shapes, without significantly reducing image brightness.
Implementation Method 1
The second way to reflect light is to reflect it like a mirror does, with an angle of reflection identical to the angle of incidence on the surface, following the Snell-Descartes law for reflection. This mirror reflection is characteristic of specular reflection and shiny surfaces.
Data Source
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Figure 5A~5D
AI summary
The invention relates to a device for reducing 3D surface reconstruction artifacts related to specular reflections in stereophotogrammetry using a single camera. The device comprises computing means for 3D surface reconstruction and a single camera (5) equipped with a non-polarized dual optical system (OA) and (OB) and two separate light sources (2A) and (2B) spaced the same distance apart as the dual optics and aligned with them, such that (2A) is aligned with (OA) and (2B) with respect to the observed subject (S). The computing means determine the best match among four for a specular spot according to geometric criteria.