Single Camera FOV Calibration via Ray-Based Coordinate Matrix

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Solution Overview

Problem

Current camera calibration methods do not effectively calibrate the field of view (FOV) of a single camera, limiting the ability to accurately measure object dimensions in video streams and preventing the use of Reverse Projection for object measurement tasks.

Innovation Solution

A method for calibrating the FOV of a single camera involves setting fixed installation parameters, dividing the FOV into sectioned rays, capturing images while a calibration board moves along these rays, processing the images to digitize coordinates, creating a coordination matrix, and performing extrapolation to generate a virtual grid for aligning with objects in a video stream.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional camera calibration methods are used, then image quality and focus are improved, but field of view calibration and depth perspective are not achieved

Engineering Contradiction:
Improvefield of view calibration accuracyVSAvoiddepth perspective information
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The field of view is divided into multiple sectioned rays radiating from the camera center, with calibration performed along each ray independently. This segmentation allows precise measurement of depth and angle relationships without losing spatial information.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The calibration process extends from traditional 2D image plane calibration to 3D spatial calibration by moving the calibration board along rays in depth and angle, capturing coordinates at multiple locations to build a coordination matrix that preserves depth perspective.

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

2Measurement precision

If multiple cameras are used for object size measurement, then measurement accuracy is improved, but system complexity and cost increase

Engineering Contradiction:
Improveobject size measurement accuracyVSAvoidnumber of cameras required
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

A single camera performs all calibration and measurement functions by itself through the ray-based coordination matrix method, eliminating the need for multiple cameras while maintaining measurement accuracy through mathematical extrapolation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system changes the calibration approach from requiring multiple simultaneous camera views to using a single camera with extended calibration along multiple rays at different depths and angles, allowing the same measurement capability with fewer devices.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If Reverse Projection method is applied without FOV calibration, then object identification is possible, but accurate dimension extraction cannot be achieved

Engineering Contradiction:
Improveobject dimension extraction accuracyVSAvoidoperation simplicity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The field of view is pre-calibrated by establishing a coordination matrix along sectioned rays before actual measurement operations. This preliminary calibration enables accurate dimension extraction during Reverse Projection without adding complexity to the operational workflow.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS12323575B2Dimensional calibration of the field-of-view of a single camera
Publication Date: 2025.06.03 BOROVSKY IGOR
  • US12323575B2 patent drawing
  • US12323575B2 patent drawing
  • US12323575B2 patent drawing

AI summary

A method for calibrating an active FOV of a single camera, wherein from the calibration of the cameras active FOV, a coordinate matrix is obtained which remotely produces a virtual interpolation measurement network at any point within an image (a frame) extracted from a video stream (recorded by the single camera), while eliminating the need to be physically located at the actual location where the video stream has been recorded. According to an embodiment of the invention, the basis of the active FOV of a camera is the ability to obtain (measure) coordinates of the measurement points marked on a calibration board.