Actuation Mechanism Calibration for 3D Scanner Fill-Factor
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Solution Overview
Problem
Current 3D sensing technologies, such as time-of-flight camera systems, face limitations in depth measurement accuracy and range due to background illumination from sources like direct sunlight, which increases noise and reduces depth-sensing capability, especially at longer distances.
Innovation Solution
The proposed solution involves an apparatus with an actuation mechanism that moves non-uniform illumination across the field of view, allowing for calibration of gain values to optimize the fill-factor of the illumination coverage, thereby improving depth-sensing accuracy and range without directly measuring actuator motion or external pattern projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If uniform illumination is emitted across the field of view, then the coverage area is maximized, but the depth measurement accuracy deteriorates due to background illumination noise
Solution Approach 1:
The patent applies local quality by transitioning from uniform illumination to spatially-nonuniform illumination, where different regions of the field of view receive different illumination intensities. The actuation mechanism moves the illumination to selectively cover only the currently measured region, ensuring high illumination intensity where needed while leaving other regions dark, thus reducing background noise and improving depth measurement accuracy without sacrificing overall coverage.
Solution Approach 2:
The patent implements dynamics by making the illumination pattern movable through an actuation mechanism. Instead of static uniform illumination, the system dynamically relocates the illumination across different regions of the field of view in sequence. This dynamic approach allows the same illumination source to provide both high intensity coverage (when focused) and complete scene coverage (when moved through multiple positions), resolving the contradiction between coverage area and measurement precision.
2Measurement precision
If the illumination is focused on specific areas to improve depth sensing, then the depth measurement accuracy improves, but the fill-factor of illumination coverage deteriorates
Solution Approach 1:
The actuation mechanism enables the illumination to dynamically move across multiple positions in the field of view. At any given moment, the illumination is focused on a specific area to provide high intensity and accurate depth sensing. However, by sequentially visiting multiple positions, the system achieves complete or near-complete coverage of the entire field of view over time, thus maintaining a high fill-factor despite the focused nature of the illumination at each instant.
3Length of stationary object
If more electrical power or optical flux is provided to increase illumination intensity, then the depth sensing range improves, but the system complexity and power consumption increase
Solution Approach 1:
Instead of increasing power to illuminate the entire field of view simultaneously, the system uses a low-power illumination source that is moved dynamically across the field of view. The actuation mechanism sequences the illumination through multiple positions, ensuring that each region receives adequate illumination intensity for accurate depth sensing, while the overall power consumption remains low because the high-intensity illumination is applied to only one region at a time rather than all regions simultaneously.
Data Source
AI summary
Embodiments of the present techniques provide apparatus and methods for calibrating the actuation mechanism (506) of an imaging system (500) for generating a three-dimensional (3D) representation of a scene (508). In particular, the present techniques provide for setting the gain of for the actuation mechanism (506) to a plurality of different gain values, determining a fill-factor for the field of view associated with each of the different gain values and determining a calibrated gain value based on the results. An apparatus (500) comprises a light source (502), e.g. a VCSEL array. The light emitted by the light source (502) passes through one or more optical elements (504), e.g. lenses, mirrors, diffraction gratings, etc., before being emitted from the apparatus (500) and projecting onto the scene/object field (508). The apparatus (500) comprises a receiver lens and filter system (510), and a multipixel sensor/detector (512) for sensing reflected light. One or more of the optical elements (504) are coupled to an actuation mechanism (506). The actuation mechanism (506) moves the optical element (504) to which it is coupled. The extent by which the optical element (504) is moved depends on the gain for the actuation mechanism (506). A control signal is provided to the actuation mechanism (506). The control signal is amplified by the gain. The amplified signal is applied to the actuation mechanism (506). Applying the gain calibration techniques to a structured-light 3D scanner may be used to increase the fill-factor.