Dynamic Projection Patterns for 3D Scanning of Translucent Surfaces
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Solution Overview
Problem
Structured light scanning methods face challenges when measuring translucent objects, as projected light penetrates and is diffused within the object, leading to reduced contrast and noise interference, making it difficult to detect features and obtain accurate 3D measurements.
Innovation Solution
A camera system utilizing an optical array generator to project dynamic patterns onto an object's surface, with independently controlled light sources and a lens array to form sub-images, which reduces noise and increases data density by varying the luminosity and pattern sequence, allowing for effective 3D surface profiling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the amount of light on the sensor is increased to reduce shot noise, then the signal-to-noise ratio improves, but the full-well capacity of the image sensor pixels is exceeded
Solution Approach 1:
The patent applies temporal modulation by projecting patterns at different time points (e.g., first pattern at time t1, second pattern at time t2) and combining the measurements. This periodic temporal action allows the system to achieve high signal-to-noise ratio through temporal integration without requiring excessive light intensity at any single moment, thus avoiding sensor saturation.
Solution Approach 2:
The system dynamically adjusts the projection pattern over time, using multiple temporally separated measurements instead of a single static high-intensity measurement. This dynamic approach allows optimization of both signal strength and noise reduction while respecting sensor capacity limits.
2Measurement precision
If structured light patterns are projected onto translucent objects, then 3D surface information can be obtained, but the light is diffused within the object causing reduced contrast and increased noise
Solution Approach 1:
The patent segments the measurement process into multiple temporal steps, projecting different patterns at different time points. By separating the measurement into discrete temporal segments and combining the results, the system can distinguish between surface-reflected light (which carries 3D information) and internally diffused light (noise), thereby improving measurement precision on translucent objects.
Solution Approach 2:
The system uses feedback from multiple pattern projections and their corresponding captured images to iteratively improve the measurement. By analyzing the response to different patterns over time and adjusting subsequent measurements, the system can compensate for the diffusive effects in translucent materials and extract accurate 3D surface information.
3Measurement precision
If multiple structured illumination patterns are projected in sequence, then data density increases for accurate 3D reconstruction, but the measurement time increases
Solution Approach 1:
The patent employs periodic temporal modulation where patterns are projected in a systematic sequence over time. This periodic approach allows the system to efficiently capture multiple measurements with optimized timing, achieving high data density while minimizing total measurement time through structured temporal sampling.
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 system enhances the signal-to-noise ratio and maintains data density by reducing average irradiance while maintaining signal amplitude, enabling accurate 3D reconstruction of non-planar surfaces, even in translucent materials.
Implementation Method 1
a lens array comprising a plurality of lenses constructed to image light from the light source onto an image plane to form the plurality of dynamic patterns
Implementation Method 2
a collimator constructed to direct light of the light source onto the lens array
Implementation Method 3
an imaging sensor arranged within the camera to record a plurality of reflected images formed from reflection of the plurality of dynamic patterns
Implementation Method 4
a first imaging optics arranged within the camera to focus the plurality of dynamic patterns onto a surface of an object to be measured
Data Source
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AI summary
A device, method and system for utilizing an optical array generator to generate dynamic patterns in a dental camera for projection onto the surface of an object, while reducing noise and increasing data density for three-dimensional (3D) measurement. Projected light patterns are used to generate optical features on the surface of the object to be measured and optical 3D measuring methods which operate according to triangulation principles are used to measure the object.