PTZ Camera Field Angle Auto-Calibration via Image Matching

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Solution Overview

Problem

The existing methods for determining the field angle of dome cameras are labor-intensive, cumbersome, and not suitable for many application scenarios, as they rely on manual calibration and approximation, which can lead to inaccuracies in positioning subjects.

Innovation Solution

A method and system that automatically determine the target field angle by capturing two images with the PTZ camera at different angles, calculating matching errors between overlapped pixels, and iteratively refining the field angle range to find the angle with the smallest matching error, thereby reducing labor costs and improving accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If manual calibration method is used to determine field angle, then the process can be completed with simple equipment, but the labor cost is high and the process is complicated

Engineering Contradiction:

Improveequipment simplicityVSAvoiddetermination efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The system automatically captures images, identifies features, calculates coordinates, and determines field angle without human intervention. The computer executes the entire calibration process autonomously by processing images from the image capturing device and computing the field angle based on detected feature points and their coordinates.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The manual mechanical calibration process is replaced with an automated computer-based image processing system. Instead of manual observation and calculation, the system uses digital image capture, automated feature detection algorithms, and computational geometry to determine the field angle.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If manual calibration method is used to determine field angle, then the equipment required is simple, but the process is cumbersome and not suitable for many application scenarios

Engineering Contradiction:

Improveequipment simplicityVSAvoidprocess simplicity

Core Design Contradiction:

Ease of manufactureVSEase of operation

Solution Approach 1:

The system performs self-calibration by automatically capturing images, detecting features, calculating coordinates, and determining field angle without requiring operator intervention at each step. The computer autonomously executes the entire calibration workflow.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The cumbersome manual calibration process is replaced with an automated computer-based system that uses digital image processing and algorithmic coordinate calculation, eliminating the need for manual operations while maintaining equipment simplicity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If calibration value is used for positioning subject, then the process is simple, but the positioning accuracy is insufficient

Engineering Contradiction:

Improvepositioning process simplicityVSAvoidpositioning accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system performs preliminary automatic calibration to determine an accurate field angle before positioning operations. By pre-calculating the precise field angle through automated image processing and coordinate analysis, the system ensures high positioning accuracy for subsequent subject identification and localization tasks.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The approximate calibration value approach is replaced with automated image-based field angle determination. The system captures images, detects feature points, calculates their coordinates, and computes the precise field angle using computational geometry, thereby achieving high positioning accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If iterative refinement method is used to determine field angle, then the positioning accuracy is improved, but the calculation complexity increases

Engineering Contradiction:

Improvefield angle accuracyVSAvoidcalculation process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system uses feedback from image feature detection and coordinate calculation to iteratively refine the field angle determination. By comparing detected feature positions with expected positions based on the current field angle estimate, the system adjusts and converges to the accurate field angle value.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The complex iterative refinement process is implemented through automated computer algorithms that perform repeated calculations and adjustments. The computer systematically processes images, detects features, calculates coordinates, and refines the field angle estimate through multiple iterations until convergence is achieved.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11575838B2Systems and methods for determining a target field angle of an image capturing device

Publication Date: 2023.02.07 ZHEJIANG DAHUA TECH CO LTD

AI summary

The present disclosure relates to systems and methods for determining automatically a target field angle of an image capturing device. The method may include obtaining, by the image capturing device, at least two images for determining a target field angle of the image capturing device. The method may also include obtaining a field angle range of the image capturing device. Further, the method may include determining the target field angle by matching the at least two images based on the field angle range.