ToF Multipath Mitigation via Spatial Pattern Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Time-of-flight systems face challenges in accurately separating direct and global light components, leading to reduced signal-to-noise ratios and impaired depth imaging due to multipath interference.
Innovation Solution
A method involving the acquisition of multiple images using different spatial patterns and modulation frequencies, followed by the application of denoising coefficients to separate direct and global light components, enhancing the signal-to-noise ratio through a multipath mitigation module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple images are acquired using different spatial patterns and modulation frequencies, then the separation of direct and global light components is improved, but the complexity of the system increases
Solution Approach 1:
The patent segments the light signal into direct and global components by acquiring multiple images with different spatial patterns (e.g., uniform, horizontal, vertical patterns) and modulation frequencies. Each pattern captures different proportions of direct and global light, allowing mathematical separation of the components through solving a system of equations.
Solution Approach 2:
The patent employs periodic modulation of the light source at different frequencies combined with periodic switching between different spatial patterns. This periodic action enables the separation of direct and global light components by analyzing the temporal and spatial variations in the captured images.
2Measurement precision
If denoising coefficients are applied to increase signal-to-noise ratio, then the quality of depth imaging is improved, but the processing time increases
Solution Approach 1:
The patent performs denoising operations as a preliminary step before final depth calculation. By applying denoising coefficients to the acquired images and separated light components before computing the final depth map, the method reduces noise propagation to subsequent processing stages, improving overall efficiency despite the additional initial processing time.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A time-of-flight (ToF) system (100) disclosed herein provides a method of separating a direct component of light (112) collected by a ToF detector from a global component of light (112a, 112b) collected by the ToF detector (120), the method comprising acquiring three or more images represented by three or more matrices in response to illuminating a target (150) with a light source using a first spatial pattern (132a, 132b, 132c) at three or more different modulation frequencies, acquiring an additional image represented by an additional matrix in response to illuminating the target with the light source using a second spatial pattern (134), the second spatial pattern being different than the first spatial pattern, and determining one or more parameters of the direct component of light (112) and the global component of light (112a, 112b) based on analysis of the three or more matrices and the additional matrix. The direct component is due to the direct illumination of a point in the scene by the source of light and the global component is due to the indirect illumination of the scene point. A ToF module (102) includes a computing module (104) that includes a processor (106) and a spatial pattern data store (108). The spatial patterns (132a, 132b, 132c and 134) are two dimensional patterns that map to the two-dimensional grid of light source elements (110a, 110b). Light source (110) may include a large number of light source pixels. The scattering of each of the direct light component (112) and the global light component (112a) at the point (154) results in a total light signal (114) that is captured by a camera (120) of the ToF module (102). The combination of imaging lens (116), light sampling array (124), and sampler (124) receives and converts the total light signal (114) into a sampled signal (126) that is communicated to a multipath mitigation module (128). The multipath mitigation module 128 includes an image analyzer (130) that analyzes images captured by the camera (120) to determine various parameters of a direct component and a global component of the total light signal (114. 44). A denoising module (140) generates a denoising coefficient ξ(m,n) to increase the signal to noise ratio (SNR) where m and n denote a size of a kernel matrix applied to each pixel location.