AR Coordinate Mapping Using Displayed Fiducial Markers

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Solution Overview

Problem

In multi-device augmented-reality systems, maintaining consistent presentation of virtual objects across devices is challenging due to differing coordinate systems, requiring transformation between these systems without relying on fixed reference points in the environment.

Innovation Solution

A method for mapping coordinate systems of multiple devices using fiducial markers, where one device presents a marker on its display, and another device captures this marker to derive a transformation between their coordinate systems through image processing and perspective-n-point techniques, enabling coherent presentation of virtual objects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If coordinate systems of multiple devices are mapped using fiducial markers, then consistency of virtual object presentation across devices is improved, but device complexity increases due to additional markers and image processing requirements

Engineering Contradiction:
Improveconsistency of virtual object presentationVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces fiducial markers as intermediary objects that facilitate coordinate system mapping between devices. These markers serve as a common reference medium that both devices can detect and use to establish their spatial relationship, thereby improving presentation consistency while keeping each device's processing requirements manageable.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses fiducial markers as simplified copies or representations of reference objects. Instead of requiring devices to directly recognize and interpret complex environmental features, the system employs standardized marker patterns that can be easily detected and used for coordinate transformation, reducing processing complexity.

Inventive Principle:
Principle #26Copying

2Measurement precision

If fiducial markers are used for coordinate system mapping, then transformation accuracy between devices is improved, but the system requires additional physical markers in the environment

Engineering Contradiction:
Improvecoordinate transformation accuracyVSAvoidnumber of fiducial markers
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent designs fiducial markers with universal functionality that serves multiple purposes: they establish coordinate relationships, provide scale references, and enable pose estimation. This multi-functionality allows accurate transformation with fewer markers compared to systems requiring separate reference objects for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent employs fiducial markers with specific geometric parameters and patterns that optimize detection accuracy. By carefully designing marker dimensions, patterns, and arrangements, the system achieves high transformation precision while minimizing the number of markers needed.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4058874B1Method and system for associating device coordinate systems in a multi-person ar system
Publication Date: 2026.03.18 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD
  • EP4058874B1 patent drawingFigure 1
  • EP4058874B1 patent drawingFigure 2~3A
  • EP4058874B1 patent drawingFigure 3B

AI summary

Methods and systems are disclosed mapping the coordinate systems of devices for an augmented-reality application. A first pose defined relative to a first coordinate system associated with a first mobile device may be received by a second mobile device. An image of a display of the first mobile device presenting a fiducial marker may be received by the second mobile device. Data indicating three-dimensional coordinates of the first mobile device can be identified and used to define a second pose of the second mobile device associated with the coordinate system of the first device. A coordinate-system transform that maps coordinates between the first coordinate system of the first mobile device and the second coordinate system of the second mobile device can be generated using the second pose. A first virtual object can be presented on a display of the second mobile device based on the coordinate-system transform.