Time-of-Flight Camera Multi-Path Error Compensation
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Solution Overview
Problem
State-of-the-art 3D time-of-flight cameras suffer from erroneous measurements due to multiple reflections in the scene caused by parallel illumination over the full field-of-view, which affects the accuracy of depth measurements.
Innovation Solution
The use of two spatially different illumination schemes, one for achieving high lateral resolution and the other to reduce multi-path errors by structuring the emitted light, allowing the combination of these into a single field-of-illumination to maintain high resolution while minimizing multi-path errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parallel illumination over the full field-of-view is used, then lateral resolution is improved, but measurement precision deteriorates due to multiple reflections
Solution Approach 1:
The field-of-illumination is divided into two distinct patterns: a first FOI for capturing high-resolution depth information and a second FOI for capturing multi-path compensated depth information. By segmenting the illumination into these two functional parts, the system can simultaneously achieve high lateral resolution while reducing multi-path errors through the second FOI's structured illumination pattern
2Device complexity
If a single field-of-illumination is used, then device complexity is reduced, but measurement precision deteriorates due to inability to compensate multi-path errors
Solution Approach 1:
Two separate depth maps captured with different illumination schemes are merged into a single compensated depth map. The first depth map provides high lateral resolution while the second depth map provides multi-path error compensation. By combining these two measurements, the system achieves both high resolution and accuracy without requiring a single complex illumination scheme
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 effectively reduces multi-path errors while maintaining high lateral resolution, enabling more accurate and reliable depth measurements by combining depth maps captured with different illumination schemes.
Implementation Method 1
TOF systems are based on the phase-measurement technique of emitted intensity-modulated light, which is reflected by the scene
Implementation Method 2
intensity-modulated light, which is reflected by the scene
Implementation Method 3
The reflected light is imaged onto a sensor. The photo-generated electrons are demodulated in the sensor
Implementation Method 4
erroneous measurements caused by multiple reflections in the scene
Data Source
AI summary
Due to their parallel illumination and acquisition for all the pixels, today's state-of-the-art time-of-flight (TOF) range cameras suffer from erroneous measurements caused by multiple reflections in the scene. The invention proposes to compensate for the multi-path fusing the results obtained by applying two spatially different illumination schemes, typically one to achieve highest possible lateral resolution and for the second one structuring the emitted light and by doing so lowering the lateral resolution but limiting the impact of multiple reflections.