ToF Depth Estimation Using Non-Saturated Spot Pixels
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Solution Overview
Problem
Existing time-of-flight (ToF) systems face challenges in accurately determining depth information due to saturation of peak pixel values in spot pixel regions, particularly for objects close to the light source or with high reflectivity, which can lead to discarded data and increased acquisition time for capturing depth information of the whole scene.
Innovation Solution
An image processing circuitry that generates component data from ToF measurements, calculates phase amplitude values, identifies spot and valley pixel regions, determines non-saturated pixels within saturated regions, and uses these pixels to calculate depth values, thereby extending the dynamic range and maintaining accuracy without requiring multiple acquisitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spot ToF systems illuminate the scene with concentrated light spots to improve depth measurement precision, then measurement precision is improved, but pixel saturation occurs for close or highly reflective objects causing loss of information
Solution Approach 1:
The patent changes the parameter of light intensity distribution by introducing a light intensity map that varies across different regions. By assigning different light intensities to different spatial regions (higher intensity for far regions, lower intensity for near regions), the system extends dynamic range and prevents saturation while maintaining measurement precision across varying depths
Solution Approach 2:
The patent applies local quality by using region-specific light intensity settings. Different regions of the scene are illuminated with different light intensities tailored to their expected depth characteristics. This allows optimal measurement conditions for each region without causing saturation in high-risk areas
2Loss of information
If multiple acquisitions are performed to capture depth information of the whole scene including both far and close objects, then depth information completeness is improved, but acquisition time increases
Solution Approach 1:
The patent uses periodic modulation of the light source at different frequencies or phases for different regions. This allows the system to encode depth information for both near and far objects in a single acquisition cycle by modulating light intensity periodically across different spatial zones
Solution Approach 2:
The patent performs preliminary action by pre-calculating and storing a light intensity map that predicts optimal light intensities for different regions before the actual depth measurement. This pre-planning enables single-shot acquisition with appropriate intensity distribution, avoiding the need for multiple sequential acquisitions
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 solution allows for accurate depth estimation with an extended dynamic range, enabling simultaneous depth measurement of both far and close objects and varying reflectivity levels without increasing acquisition time or changing hardware configurations.
Implementation Method 1
time-of-flight (ToF) systems are known, which are used for determining a distance to or a depth map of (objects in) a scene that is illuminated with light. Time-of-flight includes a variety of methods that measure the time that a particle or a light wave needs to travel a distance in a medium.
Implementation Method 2
Signal depth information can be obtained from the resulting modulation.
Data Source
AI summary
An image processing circuitry for a time-of-flight system configured to: generate, based on obtained image data of a plurality of pixels representing a time-of-flight measurement of light reflected from a scene that is illuminated with spotted light, corresponding component data including component values of the plurality of pixels; calculate, based on the generated component data, corresponding phase amplitude image data including phase amplitude values of the plurality of pixels; determine, based on the calculated phase amplitude image data, spot pixel regions and a valley pixel region among the plurality of pixels; and calculate a depth value for each of the spot pixel regions in the first set of spot pixel regions.