TOF Depth Map Accuracy via Parallax Noise Filtering

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Solution Overview

Problem

Time of flight 3D camera mapping systems face signal noise due to multipath interference from surfaces and environmental reflections, which current algorithms attempt to mitigate but at the cost of increased processing and power consumption.

Innovation Solution

The system employs non-mathematical assumptive rules and sequential viewing with parallax adjustments to reduce multipath noise by shifting the position of the TOF system to create additional views, allowing object recognition to filter out extraneous data and select the less noisy view for improved 3D depth mapping accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If computational algorithms are used to reduce multipath interference, then 3D depth mapping accuracy is improved, but processing power consumption increases

Engineering Contradiction:
Improve3D depth mapping accuracyVSAvoidprocessing power consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system performs preliminary actions by capturing multiple images from different positions before processing. The TOF system is moved to multiple locations to capture images in advance, and the selection of the best image is made after capture but before final processing, thereby reducing the need for computationally intensive multipath filtering algorithms

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The harmful multipath interference is extracted and removed by selecting only the direct reflection path. The system identifies and extracts the cleanest image with the least multipath interference by comparing multiple captured images, thereby eliminating the need for complex algorithms to filter out noise

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If computational algorithms are used to reduce multipath interference, then 3D depth mapping accuracy is improved, but device complexity increases

Engineering Contradiction:
Improve3D depth mapping accuracyVSAvoidalgorithm complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The complex multipath filtering algorithms are replaced by extracting the essential information from multiple captured images. The system simply compares and selects the image with the least interference, thereby reducing device complexity while maintaining accuracy

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using complex algorithms to process a single image, the system creates multiple copies of the scene from different positions and selects the best copy. This approach replaces computational complexity with physical redundancy

Inventive Principle:
Principle #26Copying

3Measurement precision

If multiple views with parallax are captured, then multipath noise is reduced, but imaging time increases

Engineering Contradiction:
Improve3D depth mapping accuracyVSAvoidimaging time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

Multiple images are captured in advance from different positions, and the selection is made after capture. This preliminary action allows the system to gather all necessary data before processing, reducing the time needed during actual operation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system captures more images than strictly necessary (excessive action) to ensure that at least one image with minimal multipath interference is obtained. This approach trades some imaging time for reliable accuracy

Inventive Principle:
Principle #16Partial or excessive action

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 3D depth mapping accuracy by reducing noise from reflections, specifically from surfaces like walls and ceilings, without the computational intensity of traditional algorithms, thereby improving the system's efficiency and reducing power consumption.

Implementation Method 1

timing the periods from laser transmission to reception of each reflection

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

The time of flight for each detected reflection by a sensor, typically a complementary metal oxide semiconductor (CMOS) camera, is converted to distance to generate the depth map

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Implementation Method 3

the position of the TOF system can be shifted in one or more axes, to create an additional view which produces parallax relative to the initial view

Methodology Applied
Scientific EffectParallax: Parallax

Data Source

PatentUS10979695B2Generating 3D depth map using parallax
Publication Date: 2021.04.13 SONY GROUP CORP
  • US10979695B2 patent drawing
  • US10979695B2 patent drawing
  • US10979695B2 patent drawing

AI summary

Parallax views of objects are used to generate 3D depth maps of the objects using time of flight (TOF) information. In this way, the deleterious effects of multipath interference can be reduced to improve 3D depth map accuracy without using computationally intensive algorithms.