TOF Camera Depth Accuracy via Discrete Illumination Patterning
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Solution Overview
Problem
Time-Of-Flight camera systems face errors in depth measurements due to direct and indirect reflections of light, leading to inaccurate distance calculations, with existing methods being costly or inefficient in isolating the direct component of reflected light.
Innovation Solution
A method and system that modify illumination to distinguish between direct and indirect light by creating discrete intensity patterns on the scene, using patterning means like masks or grids to eliminate indirect light influences in depth maps, allowing for accurate distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple frequency approaches are used to recover direct component of light, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the spatial distribution parameter of illumination by projecting patterns with varying intensities across different regions of the scene. This allows differentiation between direct and indirect light components through spatial analysis rather than temporal frequency analysis, achieving accurate depth measurement without complex multi-frequency modulation systems
2Measurement precision
If Digital Light Processing projector is used to create spatial patterns, then direct and indirect light components can be separated, but manufacturing cost increases
Solution Approach 1:
The patent segments the illumination into multiple discrete regions with different intensity levels. By dividing the scene into elementary areas and illuminating them with distinct intensity patterns, the system can separate direct and indirect light components through simple intensity comparison, avoiding the need for expensive DLP projectors
Solution Approach 2:
The patent employs cost-effective illumination modification techniques such as masks or simple optical elements instead of expensive programmable DLP projectors. These inexpensive components can be easily manufactured and replaced, achieving the same light separation function at a fraction of the cost
3Use of energy by moving object
If secondary reflections are captured by the sensor, then more light signal is received, but measurement precision deteriorates due to distorted delay
Solution Approach 1:
The patent extracts and eliminates the harmful indirect light components from the captured signal. By analyzing the spatial intensity distribution and identifying regions dominated by indirect reflections, the system removes these distorted signals from the depth calculation, retaining only the direct light component for accurate measurement
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 accurate and cost-effective measurement of object distances by isolating direct light components, reducing errors in depth maps and improving measurement resolution.
Implementation Method 1
TOF camera system captures 3D images of a scene by analysing the time of flight of light from a dedicated illumination unit to an object
Implementation Method 2
The modulated light is reflected back from objects within the scene
Implementation Method 3
modifying in a discrete way the illumination of said illumination unit in order to illuminate elementary areas of the scene with different incident intensities
Data Source
AI summary
The invention relates to a method for measuring a distance between an object of a scene and a Time-Of-Flight camera system, and providing a depth map of the object, the Time-Of-Flight camera system comprising an illumination unit, an imaging sensor having a matrix of pixels and image processing means, the method being characterized by the following steps: modifying in a discrete way the illumination of said illumination unit in order to illuminate elementary areas of the scene with different incident intensities, respectively, for distinguishing the direct incident light beams from the indirect incident light beams; receiving onto the pixels of the matrix of the sensor the beams reflected by said elementary areas and providing the image processing means with corresponding data; processing the said corresponding data for eliminating the influence of the indirect light beams in the depth map of the object.