Three-Dimensional Shape Measurement With Pixel-Adaptive Exposure Control
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Solution Overview
Problem
Three-dimensional shape measurement devices using the dToF system face challenges in obtaining uniform and accurate exposure output amounts in all pixels of the image sensor due to varying reflectance, distance, and position of the measurement object, making it difficult to achieve precise distance measurements.
Innovation Solution
A three-dimensional shape measurement device and method that adjusts exposure conditions for each pixel by detecting reference exposure output amounts, calculating measurement conditions, and optimizing the number of light emissions and exposures to ensure uniform accuracy across multiple pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the exposure output amount is increased by repeating light emission and exposure multiple times, then the measurement accuracy is improved, but the measurement time is increased
Solution Approach 1:
The patent applies local quality by adjusting the number of accumulations individually for each pixel based on its specific exposure output amount. Pixels with low exposure output (such as those measuring low-reflectance materials or distant objects) receive more accumulations to achieve sufficient signal strength, while pixels with high exposure output require fewer accumulations. This pixel-specific adaptation resolves the contradiction by optimizing measurement accuracy for each pixel without uniformly increasing measurement time across all pixels.
Solution Approach 2:
The patent implements dynamics by making the number of accumulations variable rather than fixed. The computational unit dynamically calculates the required number of accumulations for each pixel based on its detected exposure output amount, allowing the system to adapt the measurement process to actual conditions. This dynamic adjustment enables the system to achieve accurate measurements while minimizing unnecessary measurement time.
2Measurement precision
If the exposure output amount is increased for all pixels uniformly, then the measurement accuracy is improved, but the processing complexity is increased
Solution Approach 1:
The patent resolves this contradiction by applying local quality through pixel-specific accumulation control. Instead of uniformly increasing exposure for all pixels, the system detects the actual exposure output of each pixel and calculates the appropriate number of accumulations individually. This approach achieves uniform measurement accuracy across different pixel types (e.g., those measuring high-reflectance vs. low-reflectance materials) while avoiding the excessive processing complexity that would result from a uniform increase applied to all pixels regardless of their individual characteristics.
Solution Approach 2:
The patent implements feedback by using the detected exposure output amount of each pixel to determine the number of accumulations required. The computational unit receives the exposure output detection results and uses this feedback information to calculate appropriate accumulation numbers for each pixel. This feedback mechanism enables the system to achieve uniform measurement accuracy while keeping control complexity manageable through automated, data-driven decision-making.
3Measurement precision
If the number of accumulations is increased for each pixel, then the measurement accuracy is improved, but the measurement speed is decreased
Solution Approach 1:
The patent applies local quality by tailoring the number of accumulations to each pixel's specific needs based on its exposure output characteristics. Pixels measuring low-reflectance materials or distant objects require more accumulations to achieve sufficient signal strength and accurate measurements, while pixels with high exposure output require fewer accumulations. This differentiated approach improves measurement accuracy for challenging pixels without unnecessarily decreasing the overall measurement speed through excessive accumulations applied to all pixels uniformly.
Solution Approach 2:
The patent implements dynamics by making the accumulation count adaptive rather than static. The system dynamically calculates the optimal number of accumulations for each pixel based on real-time exposure output detection, allowing the measurement process to adjust to actual conditions. This dynamic adaptation enables the system to maintain high measurement accuracy for difficult-to-measure pixels while preserving measurement speed by avoiding unnecessary accumulations for easier-to-measure pixels.
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 accurate and uniform three-dimensional shape measurement by optimizing exposure conditions for each pixel, improving measurement accuracy and reducing processing time.
Implementation Method 1
an imaging element having pixels and configured to: receive reflected light that is the laser light reflected by the measurement object based on a prescribed exposure condition for each pixel; perform photoelectric conversion; and output the photoelectric conversion as an output signal
Implementation Method 2
a light emitter configured to emit laser light toward a measurement object
Implementation Method 3
measuring a distance to the measurement object for each pixel under the measurement condition based on the exposure output amount for each pixel detected by the output amount detector at an exposure timing where the exposure output amount increases as a light reception timing where the reflected light for the single light emission from the light emitter is received by the imaging element is delayed to a light emission timing where the light emitter emits
Data Source
AI summary
A three-dimensional shape measurement device: obtains, as a reference exposure output amount, an exposure output amount for each pixel detected at an exposure timing where all of reflected light reflected by a measurement object for a single light emission from a light emitter is received, computes a measurement condition for each pixel based on the reference exposure output amount obtained for each pixel; measures a distance to the measurement object for each pixel under the measurement condition based on the exposure output amount for each pixel detected at an exposure timing where the exposure output amount increases as a light reception timing where the reflected light for the single light emission from the light emitter is received by an imaging element is delayed to a light emission timing of the light emitter; and generates three-dimensional shape information of the measurement object using information on the distance for each pixel.