TOF Depth Camera Phase Map Filtering for Accuracy

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Solution Overview

Problem

Time of flight (TOF) depth cameras face challenges with low accuracy, low resolution, and poor image quality, making it difficult to obtain high-accuracy depth information.

Innovation Solution

The method involves emitting light to a target object, receiving and sampling reflected light multiple times to obtain phase maps, which are then filtered using a joint bilateral filtering scheme with an amplitude map as a guiding map to enhance depth image accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional TOF depth camera methods are used, then the system is simple and fast, but the depth image accuracy and resolution are low

Engineering Contradiction:
Improvedepth image accuracyVSAvoidprocessing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing bilateral filtering on phase maps before depth image generation. The filtering process prepares the phase data in advance by removing noise and preserving edges, which improves the accuracy of subsequent depth calculations. This preprocessing step enhances measurement precision while managing processing complexity through efficient filter design.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary element by using filtered phase maps as a intermediate representation between raw sensor data and final depth images. The bilateral filtering process creates an intermediate processed phase map that serves as a mediator, improving the quality of depth information without requiring fundamental changes to the TOF measurement principle.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple phase maps are filtered using joint bilateral filtering, then noise and aliasing are reduced, but processing time increases

Engineering Contradiction:
Improvedepth information qualityVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial action by selectively filtering phase maps based on their confidence levels. Instead of uniformly filtering all phase maps with equal intensity, the method applies bilateral filtering selectively to regions and maps where it most benefits depth quality. This approach improves depth information quality while reducing unnecessary processing time on already high-quality or low-impact regions.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent utilizes parameter changes by adjusting bilateral filtering parameters dynamically based on phase map characteristics. The filtering strength, kernel size, and other parameters are adapted according to the specific phase map being processed, allowing optimal balance between noise reduction and processing efficiency for each individual map.

Inventive Principle:
Principle #35Parameter changes

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 results in a depth image with higher accuracy and improved resolution by effectively filtering noise and aliasing, leading to more precise depth information.

Implementation Method 1

a depth image formed by a time of flight (TOF) depth camera

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Data Source

PatentEP3629055B1Method and apparatus for acquiring depth image, and electronic device
Publication Date: 2022.08.03 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD
  • EP3629055B1 patent drawingFigure 1~2
  • EP3629055B1 patent drawingFigure 3~4
  • EP3629055B1 patent drawingFigure 5~6

AI summary

A method for acquiring a depth image, an apparatus for acquiring a depth image, and an electronic device are provided. The method includes the following. Light is emitted to a target object. Light reflected by the target object is received and sampling is performed a number of times, to obtain multiple phase maps. The multiple phase maps are filtered to obtain multiple filtered phase maps. The depth image is formed according to the multiple filtered phase maps.