Moiré Pattern Depth Ranging via Intensity Monotonicity

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Solution Overview

Problem

Existing three-dimensional mapping technologies using Moiré patterns face ambiguity issues due to their reliance on contouring methods, which are inherently plagued by ambiguity problems.

Innovation Solution

A method and apparatus for three-dimensional mapping that project fringes onto an object, capture images, and process them to detect and extract depth information from Moiré patterns, utilizing a locally unambiguous characteristic such as intensity or visibility, which is monotonically related to the object's depth, thereby eliminating the need to trace or count fringes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If contouring methods are used for three-dimensional mapping with Moiré patterns, then depth information can be obtained, but ambiguity problems occur in the measurement results

Engineering Contradiction:

Improvedepth measurement accuracyVSAvoidmeasurement ambiguity

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the measurement parameter from fringe position (contouring) to Moiré pattern intensity or visibility. By configuring the projector and camera so that the locally unambiguous characteristic (intensity or visibility) is monotonically related to depth, the system eliminates the ambiguity inherent in contouring methods while maintaining depth measurement capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of tracing fringe contours as in traditional methods, the patent inverts the approach by using the intensity or visibility of the Moiré pattern itself as the measurement parameter. This inversion allows direct depth extraction without the ambiguity of contour tracing

Inventive Principle:

Principle #13The other way round (Inversion)

2Measurement precision

If traditional Moiré contouring is used, then depth mapping is achieved, but the process requires tracing and counting fringes which increases complexity

Engineering Contradiction:

Improvedepth mapping capabilityVSAvoidfringe tracing and counting process

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the essential depth information from the Moiré pattern by measuring intensity or visibility, discarding the need for complex fringe tracing and counting operations. This extraction approach simplifies the measurement process while maintaining depth mapping capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical process of tracing and counting fringes with an optical measurement of Moiré pattern intensity or visibility. This substitution eliminates the complexity of manual or algorithmic fringe tracking while achieving the same depth mapping objective

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If a single set of fringes is projected, then the system is simpler, but the depth range coverage is limited due to ambiguity

Engineering Contradiction:

Improvenumber of fringe setsVSAvoiddepth range coverage

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

By changing the measurement parameter to Moiré pattern intensity or visibility with a monotonic relationship to depth, the system can use a single set of fringes to cover a larger depth range without the ambiguity that would normally require multiple fringe sets

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 provides unambiguous depth measurements by leveraging the intensity or visibility of Moiré patterns, reducing ambiguity and enabling accurate depth determination across varying locations on the object, while also allowing for configuration to cover different depth ranges.

Implementation Method 1

projecting with a projector a set of fringes on the object

Methodology Applied

Scientific EffectLight: Light

Implementation Method 2

capturing an image of the object in a camera

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 3

A Moiré pattern is formed when a first high frequency set of fringes is demodulated by means of a second high frequency set of fringes

Methodology Applied

Scientific EffectMoiré Effect: Moiré Effect

Implementation Method 4

projecting the set of fringes via a beamsplitter, and capturing radiation from the object via the beamsplitter

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS8462207B2Depth ranging with Moiré patterns

Publication Date: 2013.06.11 APPLE INC

AI summary

A method for three-dimensional mapping of an object, including projecting with a projector a set of fringes on the object and capturing an image of the object in a camera. The method further includes processing the captured image so as to detect a Moiré pattern associated with the object and so as to extract depth information from the Moiré pattern, and configuring the projector and the camera so that a locally unambiguous characteristic of the Moiré pattern is related to a depth of the object.