Multi-Sensor Depth Mapping With ToF-Based Disparity Correction
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Solution Overview
Problem
Existing depth mapping systems face accuracy issues due to mechanical and thermal changes affecting baseline and focus, with disparity-based systems being accurate at short distances and ToF systems having lower resolution and sensitivity to photon timing deviations.
Innovation Solution
A combined depth mapping system that integrates ToF-based and disparity-based methods, using a processor to compute a disparity correction function based on ToF and disparity-based depth coordinates, correcting transverse disparity and generating accurate, high-resolution depth maps across a wide range of distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If disparity-based depth mapping is used, then measurement precision is improved at short distances, but reliability deteriorates due to mechanical and thermal changes affecting baseline and focus
Solution Approach 1:
The patent combines ToF-based depth mapping and disparity-based depth mapping into a unified system. The ToF component provides reliable depth measurements independent of mechanical baseline stability, while the disparity component provides high precision at short distances. The system merges both depth maps through weighting and fusion algorithms to achieve both reliability and precision across varying conditions.
Solution Approach 2:
The system dynamically adjusts the weighting between ToF and disparity depth maps based on environmental parameters such as temperature, baseline stability, and distance. When mechanical or thermal changes affect the disparity system, the algorithm increases reliance on ToF measurements. This adaptive parameter adjustment maintains reliability while preserving measurement precision.
2Reliability
If ToF-based depth mapping is used, then reliability is improved, but measurement precision deteriorates due to lower resolution and sensitivity to photon timing deviations
Solution Approach 1:
The patent integrates ToF and disparity systems where each compensates for the other's weaknesses. The disparity-based component enhances the resolution and precision of depth measurements, particularly at short distances where its optical resolution advantage is most beneficial. The fusion algorithm optimally combines both depth maps to achieve high precision while maintaining the reliability advantage of ToF.
Solution Approach 2:
The system applies different processing quality to different spatial regions and depth ranges. At short distances where disparity precision is superior, the system gives higher weight to disparity measurements. At longer distances or when stability is critical, it prioritizes ToF measurements. This local optimization of measurement quality improves overall precision without sacrificing reliability.
3Measurement precision
If combined ToF and disparity-based depth mapping is used, then reliability and precision are improved, but device complexity increases
Solution Approach 1:
The patent designs the illumination assembly to serve dual functions: projecting structured light patterns for disparity mapping and emitting modulated light for ToF measurement. The same optical components and light sources are utilized for both depth mapping approaches, reducing the need for separate dedicated hardware and thereby limiting the increase in device complexity despite the enhanced functionality.
4Adaptability or versatility
If multi-sensor integration is implemented, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent merges ToF and disparity sensing systems into a unified depth mapping platform with shared optical components, processing pipelines, and calibration procedures. This integration approach enhances adaptability to different environments and applications while controlling complexity through component sharing and unified system architecture.
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 provides robust and accurate depth mapping with high transverse resolution and improved accuracy, compensating for calibration changes and environmental factors, and enhances the precision of both short-range and long-range measurements.
Implementation Method 1
Other depth mappers measure depth by sensing the time of flight (ToF) of photons transmitted to and reflected back from points in a target scene
Implementation Method 2
Some depth mapping systems compute depth coordinates by measuring transverse disparity between the features in a two-dimensional image captured of a target scene and corresponding features in a reference image
Implementation Method 3
a depth map can be generated by measuring the transverse disparity at each point
Implementation Method 4
a range sensor measures the round-trip times of flight of the pulses as they travel from the radiation source to the target scene and back to the sensor
Data Source
AI summary
Depth mapping apparatus includes an illumination assembly, which directs modulated optical radiation toward a target scene, and a camera, which captures a two-dimensional image of the target scene. A range sensor senses respective times of flight of photons reflected from a matrix of locations disposed across the target scene. A processor derives first depth coordinates of the matrix of locations responsively to the respective times of flight, derives second depth coordinates of the matrix of locations responsively to a transverse disparity between features in the two-dimensional image and corresponding reference features in a reference image, computes a disparity correction function based on a difference between the first and the second depth coordinates at the matrix of locations, corrects the transverse disparity between the two-dimensional image and the reference image using the disparity correction function, and generates a depth map of the target scene based on the corrected transverse disparity.