Multi-Camera Coordinate Mapping for Precise 3D Head Tracking

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Solution Overview

Problem

Existing virtual reality systems face challenges in accurately tracking user movements and maintaining a consistent viewpoint within virtual environments, particularly in augmented and virtual reality applications, due to limitations in detecting and processing head movements and spatial orientation.

Innovation Solution

The system employs a combination of hardware motion detectors, such as piezoelectric accelerometers and optical fiber gyroscopes, along with camera-based motion sensing using optical flow detection, to track head movements and adjust the displayed images accordingly, ensuring accurate viewpoint tracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If camera-based motion sensing using optical flow detection is used, then measurement precision of head movements is improved, but device complexity increases due to multiple cameras and processing requirements

Engineering Contradiction:
Improvehead movement detection precisionVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines hardware motion detectors (accelerometers and gyroscopes) with camera-based optical flow detection into a unified motion sensing system. The processor integrates data from both the hardware sensors and camera images to generate comprehensive motion signals, thereby improving measurement precision while managing system complexity through coordinated operation of multiple components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The processor acts as an intermediary that fuses data from hardware motion detectors and camera-based optical flow detection. By processing and combining signals from both sources, the system achieves higher measurement precision for head movements while the processor manages the complexity of coordinating multiple sensing modalities.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If hardware motion detectors like accelerometers and gyroscopes are used, then reliability of motion detection is improved, but use of energy increases due to continuous operation of multiple sensors

Engineering Contradiction:
Improvemotion detection reliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically switches between hardware motion detectors and camera-based sensing modes depending on operational requirements. The processor can utilize hardware detectors for continuous reliable motion detection while periodically using camera-based optical flow to update position data, thereby maintaining reliability while reducing overall energy consumption by not operating all sensors at maximum capacity continuously.

Inventive Principle:
Principle #15Dynamics

3Productivity

If multiple cameras with overlapping fields of view are used, then productivity of tracking coverage is improved, but device complexity increases due to coordinate system mapping requirements

Engineering Contradiction:
Improvetracking coverage efficiencyVSAvoidcoordinate mapping complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent extends tracking from two-dimensional camera images to three-dimensional space by using multiple cameras with overlapping fields of view. The processor maps detected locations from multiple camera coordinate systems into a unified three-dimensional representation of the play area, enabling comprehensive tracking coverage. This dimensional extension improves productivity by covering the entire play area while the processor manages the complexity of multi-coordinate system mapping.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 the user's immersion and interaction within virtual environments by providing precise and responsive viewpoint adjustments, improving the overall virtual reality experience.

Implementation Method 1

hardware motion detectors, such as piezoelectric accelerometers

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

optical fiber gyroscopes

Methodology Applied
Scientific EffectGyroscope effect: Gyroscope

Implementation Method 3

camera-based motion sensing using optical flow detection

Methodology Applied
Scientific EffectOptical flow detection:

Data Source

PatentEP3973698B1Data processing
Publication Date: 2026.02.11 SONY INTERACTIVE ENTERTAINMENT LLC
  • EP3973698B1 patent drawingFigure 1~2
  • EP3973698B1 patent drawingFigure 3
  • EP3973698B1 patent drawingFigure 4~5

AI summary

A data processing device comprises a plurality of cameras arranged according to a predetermined configuration, wherein each camera is configured to capture successive images and to detect a current location of one or more elements in the captured images with respect to a coordinate system of the camera, a processor to generate a common camera coordinate system in dependence upon the respective coordinate systems of the plurality of cameras, the common camera coordinate system comprising a set of locations in a three-dimensional space included within the field of view of the plurality of cameras, and a detector to detect a current location of a given element with respect to the common camera coordinate system based on images captured by the plurality of cameras, wherein for each camera, the processor is configured, in response to a detection by the detector that the current location of the given element corresponds to a location in the set of locations of the common camera coordinate system, to generate first data for that location in the set of locations indicative of a mapping between the coordinate system for the camera and the common camera coordinate system, and wherein in response to a detection of a location in the set of locations for which the first data is indicative of the mapping for two or more cameras with respect to the common camera coordinate system, the processor is configured to generate second data for that location indicative of a mapping between the coordinate systems for the two or more cameras.