Stereo Camera Deformation Compensation for Accurate 3D Measurement

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Solution Overview

Problem

Existing stereo camera systems face inaccuracies in 3D measurements due to geometrical deformations caused by inertial forces, which are not adequately addressed by current calibration methods, leading to a loss in measurement accuracy.

Innovation Solution

A method and computer program product that compensates for imaging errors by using an inertial variable vector, such as a gravity vector, to update external camera parameters through a calibrated analytic deformation model, accounting for geometric deformations in stereo cameras.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a stereo camera is used with multiple orientations, then the adaptability of the camera system is improved, but the measurement precision deteriorates due to geometrical deformation from inertial forces

Engineering Contradiction:
Improveorientation flexibilityVSAvoid3D measurement accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system performs preliminary calibration by capturing images of a calibration object at multiple known orientations. This preliminary data is used to pre-compute deformation compensation parameters that are stored for later use during actual measurements, eliminating the need for real-time complex calculations while maintaining accuracy across different orientations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the external camera parameters based on the detected orientation and inertial forces. By dynamically adjusting these parameters according to the current operational state, the system compensates for geometrical deformation and maintains measurement precision across various orientations and load conditions.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If calibration is performed assuming a rigid common holder, then the calibration process is simplified, but the measurement precision deteriorates when the holder deforms under load

Engineering Contradiction:
Improvecalibration process complexityVSAvoid3D measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The system transitions from a static rigid holder assumption to a dynamic model that accounts for elastic deformation. The common holder is modeled as a flexible structure whose deformation can be predicted based on applied loads and orientation, allowing the calibration process to compensate for these dynamic changes while maintaining reasonable complexity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system replaces the mechanical assumption of rigidity with a computational elastic deformation model. Instead of physically making the holder rigid, the system uses mathematical models to predict and compensate for the elastic deformation that occurs under various load conditions, achieving accuracy without increasing physical complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If accurate calibration in the micrometer range is performed, then the measurement precision is improved, but the ease of operation deteriorates due to the laborious calibration process

Engineering Contradiction:
Improvecalibration accuracyVSAvoidcalibration effort
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system performs the complex high-precision calibration work in advance by capturing images of a calibration object at multiple known orientations. This preliminary calibration establishes a deformation model that can be automatically applied during operation, achieving micrometer-level accuracy without requiring repeated laborious calibration procedures.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses its own imaging capability to perform the calibration process. By capturing images of a calibration object and automatically processing these images to determine deformation parameters, the system calibrates itself without requiring external specialized equipment or expert intervention, significantly reducing operational effort.

Inventive Principle:
Principle #25Self-service

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

Improves 3D measurement accuracy by numerically correcting external camera parameters, thereby enhancing the precision of stereophotogrammetric analysis.

Implementation Method 1

Different orientations of a stereo camera may - due to inertial forces such as gravity or other acceleration-dependent forces - geometrically deform the stereo camera

Methodology Applied
Scientific EffectInertial force: Inertia

Implementation Method 2

Different orientations of a stereo camera may - due to inertial forces such as gravity or other acceleration-dependent forces - geometrically deform the stereo camera

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 3

geometrically deform the stereo camera, changing the relative orientation and position between the cameras of the stereo camera

Methodology Applied
Scientific EffectGeometrical deformation: Deformation

Data Source

PatentEP4033756B1Model-based compensation
Publication Date: 2026.03.11 HEXAGON INNOVATION HUB GMBH
  • EP4033756B1 patent drawingFigure 1
  • EP4033756B1 patent drawingFigure 2
  • EP4033756B1 patent drawingFigure 3

AI summary

The invention relates to a method for numerically compensating imaging errors caused by a geometrical deformation of a stereo camera (1), and to a corresponding computer program product for numerically compensating such imaging errors, and to a stereo camera (1) which acquired images are numerically compensated as in the method and computer program product according to the invention.