Depth Estimation Using Pixel Group Optical Path Differences

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Solution Overview

Problem

Existing depth estimation methods, such as DFD and phase difference detection, face challenges in achieving both speed and precision in non-contact depth measurement, with DFD requiring multiple images and phase difference detection compromising on precision due to reduced light sensitivity and increased power consumption.

Innovation Solution

A depth estimation apparatus that generates simultaneous first and second image signals with a phase difference of up to 15% using a single imaging device, employing model data to detect object position based on lens blur and phase difference, eliminating the need for multiple images and reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If DFD method is used to measure depth, then depth measurement can be achieved without multiple cameras, but multiple images with different focus positions are required which reduces speed

Engineering Contradiction:

Improvedepth measurement capabilityVSAvoiddepth estimation speed

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The imaging device is segmented into multiple pixel groups within a single imaging element, with each pixel group having a different optical path length to the image plane. This allows simultaneous capture of multiple focus planes in a single image, eliminating the need for sequential focusing operations and thereby increasing depth estimation speed while maintaining the single-camera advantage of DFD method

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a new dimension to the imaging system by varying the optical path length in the depth direction rather than using multiple cameras in spatial arrangement. This dimensional change allows the system to capture depth information through focus variation within a single imaging device, achieving both speed and depth measurement capability

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Speed

If phase difference detection method is used, then depth measurement speed is improved, but precision is reduced due to reduced light sensitivity

Engineering Contradiction:

Improvedepth measurement speedVSAvoiddepth measurement precision

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The patent changes the parameter of optical path length for different pixel groups, creating phase differences that enable depth measurement. By carefully controlling the phase difference to be within a specific range (smaller than or equal to 15% of baseline length), the system achieves both fast depth measurement and high precision by optimizing the balance between phase difference magnitude and light sensitivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If larger phase difference is used in phase difference detection, then depth measurement precision is improved, but power consumption increases due to rapid focus changes or wobbling operations

Engineering Contradiction:

Improvedepth measurement precisionVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces the mechanical focusing system (lens movement, focus changes, or wobbling operations) with an optical path length difference design at the pixel level. This substitution eliminates the need for mechanical movement to create phase differences, thereby reducing power consumption while maintaining depth measurement precision through the built-in optical path variations in different pixel groups

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 speed and precision in depth estimation while minimizing light sensitivity loss and power consumption, allowing for high-quality image capture without the need for rapid focus changes or wobbling operations.

Implementation Method 1

an imaging device which generates a first image signal and a second image signal by imaging an object at different phases

Methodology Applied

Scientific EffectPhase difference:

Implementation Method 2

DFD measures the distance based on information on lens blur, the size and shape of which change depending on the object distance

Methodology Applied

Scientific EffectLens blur: Depth of Field

Data Source

PatentUS9836847B2Depth estimation apparatus, imaging device, and depth estimation method

Publication Date: 2017.12.05 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A depth estimation apparatus including: an imaging device which generates a first image signal and a second image signal by imaging an object at different phases; a storage unit configured to store model data defining a relationship between (i) lens blur and phase difference of the object in images and (ii) position of the object in the images in the depth axis; and a detecting unit configured to detect a position of the object in the depth axis from the first image signal and the second image signal, using the model data, wherein a phase difference between the first image signal and the second image signal is smaller than or equal to 15% in terms of a base line length.