Multi-Camera Calibration Verification via Reprojection Error

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Solution Overview

Problem

Telepresence systems face challenges in optimizing camera calibration frequency to maintain high-quality 3D video reproduction without incurring excessive time and resource costs, as traditional calibration processes are time-intensive and prone to unnecessary frequency.

Innovation Solution

A method is introduced to verify camera alignment by measuring reprojection errors using a calibration target imaged by multiple cameras, determining when the alignment has drifted outside a threshold, thereby indicating the need for recalibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional calibration procedures are performed frequently to maintain camera alignment accuracy, then measurement precision is improved, but loss of time increases due to the time-intensive nature of calibration

Engineering Contradiction:
Improvecamera alignment accuracyVSAvoidcalibration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system continuously monitors camera alignment by capturing images of calibration targets and calculating reprojection errors. This feedback loop allows the system to detect when calibration has drifted and triggers recalibration only when necessary, rather than performing frequent unnecessary calibrations. The feedback mechanism resolves the contradiction by enabling precise alignment monitoring while minimizing time loss through conditional recalibration based on actual alignment status.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary calibration verification using reprojection error measurement before initiating a full recalibration procedure. By first checking whether the calibration has actually drifted beyond acceptable thresholds, the system avoids unnecessary recalibration time while ensuring alignment precision is maintained. This preliminary action filters out false calibration needs and optimizes the balance between precision and time.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If camera calibration is performed more frequently to ensure system performance, then reliability is improved, but productivity decreases due to time lost during calibration operations

Engineering Contradiction:
Improvesystem performanceVSAvoidsystem efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The feedback mechanism continuously monitors calibration status through reprojection error calculation and only triggers recalibration when alignment has actually degraded beyond acceptable thresholds. This ensures system reliability is maintained by detecting real calibration drift, while productivity is preserved by avoiding unnecessary recalibration operations that would waste time and reduce system efficiency.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts calibration frequency based on actual calibration status rather than using a fixed schedule. By making calibration operations conditional on measured alignment degradation, the system optimizes the balance between maintaining reliability through timely recalibration and preserving productivity by avoiding redundant operations. The dynamic approach allows the system to adapt calibration behavior to actual needs.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS20240193815A1Verification of a multi-camera calibration
Publication Date: 2024.06.13 GOOGLE LLC
  • US20240193815A1 patent drawing
  • US20240193815A1 patent drawing
  • US20240193815A1 patent drawing

AI summary

A method may receive first image data from a first camera and second image data from a second camera. A method may determine a calibration target position based on an extrinsic calibration, the first image data, the second image data, and calibration target information. A method may measure a first reprojection error of the first camera based on the extrinsic calibration, the calibration target position, and the first image data. A method may measure a second reprojection error of the second camera based on the extrinsic calibration, the calibration target position, and the second image data. Upon determining that any combination of the first reprojection error is greater than a threshold reprojection error or the second reprojection error is greater than the threshold reprojection error, the method may provide an indication that the first camera and the second camera are out of calibration.