Depth Imaging Multipath Interference Correction
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Solution Overview
Problem
Existing depth-imaging technologies, particularly time-of-flight (ToF) imaging, face challenges with accurate surface mapping of subjects with variable optical and material properties due to multipath interference and inability to resolve surface attributes like textures, leading to errors in depth estimation and material property determination.
Innovation Solution
A method using a depth-imaging camera that captures both depth and brightness imagery from multiple vantage points, estimating reflectivity as a function of imaging angle to correct multipath interference and determine surface properties, enabling accurate virtual three-dimensional modeling by correlating brightness and depth images and constructing a bidirectional reflectivity-distribution function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If time-of-flight imaging is used for depth mapping, then depth estimation speed and cost-effectiveness are improved, but measurement precision deteriorates due to multipath interference and inability to resolve surface attributes
Solution Approach 1:
The patent combines time-of-flight depth imaging with photogrammetry brightness imaging into a unified system. The ToF camera captures depth information while a co-located brightness camera captures surface reflectance properties. By merging these two imaging modalities and processing them together through integrated algorithms, the system achieves both high-speed depth mapping and accurate surface attribute determination, resolving the contradiction between speed and precision.
Solution Approach 2:
The patent introduces surface attribute maps (reflectance, roughness, specularity) as intermediary data structures that mediate between the raw ToF depth measurements and the final corrected depth model. These attribute maps serve as intermediaries that capture the optical properties of surfaces, allowing the system to identify and correct multipath interference effects without sacrificing depth mapping speed. The intermediary attribute information enables precision improvement while maintaining productivity.
2Device complexity
If traditional depth imaging is applied to subjects with variable optical properties, then device complexity is reduced, but measurement precision deteriorates due to multipath interference and surface attribute ambiguity
Solution Approach 1:
The patent creates a universal imaging system that can handle diverse surface properties (specular, diffuse, rough, smooth) using the same hardware configuration. The combined ToF and brightness camera system, along with unified processing algorithms, provides multi-functionality that adapts to different material properties automatically. This universal approach maintains device simplicity while achieving high precision across varied optical conditions.
Solution Approach 2:
The patent changes the parameter space by introducing surface attribute parameters (reflectance, roughness, specularity) alongside traditional depth measurements. By expanding from single-parameter depth mapping to multi-parameter surface characterization, the system achieves higher measurement precision for subjects with variable optical properties. The processing algorithms analyze variations in these parameters across multiple views to resolve ambiguities and correct multipath interference.
3Measurement precision
If multiple vantage points are used for imaging, then measurement precision is improved through better surface attribute determination, but loss of time increases due to multiple acquisitions required
Solution Approach 1:
The patent implements continuous useful action by capturing both depth and brightness images simultaneously from multiple vantage points in an integrated scan. Rather than sequentially acquiring separate depth and surface attribute data, the system continuously captures both modalities together throughout the scanning process. This continuous dual-mode acquisition reduces total scanning time while maintaining the precision benefits of multi-view imaging for surface attribute determination.
Solution Approach 2:
The patent applies preliminary action by using the brightness camera to pre-characterize surface properties during the initial scanning phase. These preliminary surface attribute measurements are then used to guide and optimize subsequent depth mapping operations, allowing the system to focus computational resources on critical areas. This preliminary characterization reduces the total time needed for high-precision surface attribute determination while maintaining accuracy.
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
This approach enhances the accuracy of depth estimation and surface attribute determination, reducing errors caused by multipath interference and allowing for reliable virtual three-dimensional modeling of complex subjects with varying optical and material properties.
Implementation Method 1
coordinate brightness and depth images of the subject are received from the depth-imaging camera. The images are acquired from each of a plurality of inequivalent vantage points.
Data Source
AI summary
A method for virtual, three-dimensional modeling of a subject using a depth-imaging camera operatively coupled to a modeling computer. A brightness image and a coordinate depth image of the subject acquired from each of a plurality of inequivalent vantage points are received from the depth-imaging camera. An angle-dependent reflectance is determined based on the brightness and coordinate depth images acquired from each of the vantage points.