Time-of-Flight Camera Stray Light Compensation Using Code Modulated Reference
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Solution Overview
Problem
Time-of-Flight (ToF) cameras experience erroneous depth measurements due to stray light from highly reflective objects, which mix with light from other objects in the scene, causing inaccurate measurements.
Innovation Solution
A method and apparatus that compensate for stray light by controlling the ToF camera to capture a reference image using a code modulated signal, limiting the measurement range to the object causing stray light, and modifying the image using the reference image to produce a compensated image that mitigates the effects of stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ToF camera captures images using continuous wave modulation, then the measurement range covers the entire scene, but stray light from highly reflective objects causes erroneous depth measurements
Solution Approach 1:
The patent segments the light measurement into two distinct components: a reference image captured with code modulated signal that contains only stray light from highly reflective objects, and a scene image captured with continuous wave modulation that contains both stray light and valid scene information. By separating these components and subtracting the reference image, the patent eliminates stray light interference while preserving accurate depth measurements.
Solution Approach 2:
The patent extracts the stray light component by capturing a reference image using code modulated signal, which isolates the stray light from highly reflective objects. This extracted stray light information is then removed from the scene image to produce a compensated image, effectively taking out the harmful stray light component while retaining valid scene depth information.
2Measurement precision
If code modulated signal is used for illumination, then stray light can be isolated and measured, but the measurement range is limited to a specific distance range
Solution Approach 1:
The patent dynamically adjusts the measurement approach by using code modulated signal specifically for capturing the reference image to isolate stray light, while using continuous wave modulation for the scene image to maintain full measurement range. This dynamic switching of modulation modes allows the system to optimize for stray light isolation when needed while preserving comprehensive scene coverage.
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 effectively corrects erroneous measurements by isolating and subtracting the stray light phasor from the measured phasor, resulting in a compensated image that is free from the influence of strong reflections, providing accurate depth measurements.
Implementation Method 1
Time-of-Flight (ToF) cameras experience erroneous depth measurements due to stray light from highly reflective objects
Implementation Method 2
controlling the ToF camera to capture a reference image of the scene using a code modulated signal for illumination
Data Source
AI summary
A method for compensating stray light caused by an object in a scene that is sensed by a time-of-flight camera is provided. The method includes receiving an image of the scene from the time-of-flight camera. Further, the method includes controlling the time-of-flight camera to capture a reference image of the scene using a code modulated signal for illumination such that a measurement range of the time-of-flight camera is limited to a distance range around the object. The method additionally includes modifying the image of the scene or an image derived therefrom using the reference image to obtain a compensated image of the scene. The method includes outputting the compensated image.