Camera Exposure Adjustment for 3D Depth Sensing and 2D Imaging
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Solution Overview
Problem
Existing distance sensors face challenges in simultaneously acquiring three-dimensional object data and two-dimensional images quickly due to issues like ambient light noise and differing optimal exposure times for each type of data acquisition, which can lead to pattern saturation and impaired image quality.
Innovation Solution
A distance sensor system that adjusts camera exposure times and light source durations to alternate between three-dimensional distance measurement and two-dimensional image capture, using a single camera capable of infrared and RGB imaging, with separate exposure settings for each mode to optimize data acquisition without the need for band-pass filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single exposure time is used for both three-dimensional depth sensing and two-dimensional imaging, then the device complexity is reduced, but the measurement precision and image quality deteriorate due to pattern saturation and ambient light noise
Solution Approach 1:
The patent applies dynamics by making the exposure time adjustable and mode-dependent. The camera controller dynamically selects between a first exposure time for depth sensing and a second exposure time for 2D imaging based on the active mode, allowing optimal exposure settings for each function without being constrained by a fixed exposure time configuration.
Solution Approach 2:
The patent changes the exposure time parameter based on the operational mode. When in depth sensing mode, a first exposure time is used that is optimized for capturing the projected light pattern. When in 2D imaging mode, a second exposure time is used that is optimized for capturing visible light images, thereby resolving the contradiction between unified device complexity and mode-specific measurement precision.
2Manufacturing precision
If a longer exposure time is used to capture clear two-dimensional images, then the image quality improves, but the three-dimensional depth sensing accuracy deteriorates due to pattern saturation
Solution Approach 1:
The system dynamically adjusts the exposure time based on the active mode. For 2D imaging, a longer second exposure time is used to capture sufficient light for high-quality images. For depth sensing, a shorter first exposure time is used to prevent the projected light pattern from saturating the sensor, thereby maintaining both image quality and depth sensing precision through mode-specific exposure settings.
Solution Approach 2:
The patent implements parameter changes by setting different exposure time values for different modes. The second exposure time for 2D imaging is longer to improve image quality, while the first exposure time for depth sensing is shorter to avoid pattern saturation. This parameter differentiation resolves the contradiction between image quality and depth sensing precision.
3Measurement precision
If a shorter exposure time is used to avoid pattern saturation in depth sensing, then the depth measurement accuracy improves, but the two-dimensional image quality deteriorates due to insufficient light capture
Solution Approach 1:
The camera controller dynamically switches between exposure time settings based on the operational mode. When performing depth sensing, a shorter first exposure time prevents pattern saturation and maintains depth measurement precision. When performing 2D imaging, a longer second exposure time captures sufficient light to produce high-quality images, thereby resolving the contradiction through adaptive parameter selection.
Solution Approach 2:
The patent changes the exposure time parameter according to the active mode to resolve the contradiction. A first (shorter) exposure time is used for depth sensing to maintain measurement precision, while a second (longer) exposure time is used for 2D imaging to ensure adequate light capture and image quality. This parameter adaptation eliminates the trade-off between the two performance metrics.
4Productivity
If the camera captures both three-dimensional and two-dimensional data simultaneously with the same exposure time, then the productivity is improved, but the reliability deteriorates due to ambient light noise and pattern saturation
Solution Approach 1:
The patent implements periodic action by alternating between depth sensing mode and 2D imaging mode in sequential frames. The camera controller switches between the first exposure time for depth sensing and the second exposure time for 2D imaging, allowing each mode to use its optimal exposure setting without interference from ambient light noise or pattern saturation, thereby maintaining both high productivity and reliability.
Solution Approach 2:
The system dynamically adjusts the exposure time based on the active mode for each capture operation. This dynamic parameter selection ensures that depth sensing uses a shorter exposure time to avoid saturation while 2D imaging uses a longer exposure time to capture sufficient light, maintaining data reliability while achieving high-speed alternating data acquisition through mode-specific optimization.
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 efficient and clear acquisition of both three-dimensional distance data and two-dimensional images in quick succession, improving pattern detection and image quality while minimizing exposure risks and ambient light interference.
Implementation Method 1
The distance from the sensor to the object can be calculated based on the appearance of the pattern in one or more images of the field of view
Implementation Method 2
The shape and dimensions of the object can also be determined
Data Source
AI summary
An example method includes setting an exposure time of a camera of a distance sensor to a first value, instructing the camera to acquire a first image of an object in a field of view of the camera, where the first image is acquired while the exposure time is set to the first value, instructing a pattern projector of the distance sensor to project a pattern of light onto the object, setting the exposure time of the camera to a second value that is different than the first value, and instructing the camera to acquire a second image of the object, where the second image includes the pattern of light, and where the second image is acquired while the exposure time is set to the second value.