Interactive Camera Calibration Tool for Lens Distortion

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Solution Overview

Problem

Existing camera calibration methods are prone to errors, especially for lenses with significant distortion, due to the user's choice of calibration images, leading to unreliable and inaccurate calibrations, particularly for novice users.

Innovation Solution

A computer-assisted method that initializes camera model parameters using image data, predicts parameters for candidate target positions, determines certainty measures, and iteratively refines the calibration by suggesting target positions until a desired accuracy is achieved, using a polynomial model to account for lens distortion and a non-linear least squares optimization method.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If standard calibration methods (MATLAB/OpenCV) are used, then calibration can be performed with basic tools, but calibration accuracy deteriorates for lenses with significant distortion

Engineering Contradiction:
Improveease of calibrationVSAvoidcalibration accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The system provides real-time feedback to users about calibration quality by displaying uncertainty estimates and guiding them to capture images at optimal positions. The software analyzes captured images and provides quantitative feedback on whether the calibration target is positioned correctly, allowing users to improve their calibration process iteratively.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent introduces an interactive software intermediary that mediates between the user and the calibration process. This software acts as a guide, providing suggestions for target positions, evaluating calibration quality, and helping users understand what constitutes a good calibration image, thereby bridging the gap between novice users and accurate calibration.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If users collect many more images than necessary, then calibration reliability improves, but time consumption and complexity increase

Engineering Contradiction:
Improvecalibration reliabilityVSAvoidcalibration time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary analysis of captured images to predict the quality of the resulting calibration before the user completes the process. By estimating uncertainty and evaluating constraint quality early in the process, the software can determine whether additional images are truly necessary, preventing unnecessary time consumption while ensuring adequate calibration reliability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The calibration system provides continuous feedback about the current state of calibration quality, allowing users to stop image collection when sufficient accuracy is achieved. The software monitors uncertainty metrics and informs users when the calibration meets desired standards, eliminating the need to collect excessive images.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If novice users perform calibration without guidance, then the process is simple to start, but calibration accuracy deteriorates due to lack of knowledge about optimization methods

Engineering Contradiction:
Improveease of useVSAvoidcalibration accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The calibration system is designed to be self-guiding, automatically evaluating the quality of captured images and providing specific instructions for improvement. The software monitors calibration progress and autonomously determines when sufficient data has been collected, reducing the need for user expertise while maintaining high calibration accuracy.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The interactive software serves as an intermediary that translates complex calibration requirements into simple user actions. It provides real-time guidance on positioning the calibration target, evaluates whether captured images meet quality standards, and communicates calibration status in user-friendly terms, making accurate calibration accessible to novice users.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS9282326B2Interactive camera calibration tool
Publication Date: 2016.03.08 THE RGT UNIV OF MICHIGAN
  • US9282326B2 patent drawing
  • US9282326B2 patent drawing
  • US9282326B2 patent drawing

AI summary

An interactive camera calibration tool is presented that provides live feedback on the state of the calibration and produces tightly-distributed calibration parameters even when used by novices. Target positions are suggested by the calibration tool. Once the target has been aligned with the target positions, image data of the target is captured and used to compute calibration parameters. This process is repeated until the computed parameters meet the accuracy requirements specified by the user. A novel calibration quality metric is also leveraged to automatically determine whether a calibration is sufficiently accurate.