Automatic Crop Row Camera Calibration via Homography

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Solution Overview

Problem

Existing crop row navigation systems relying on computer vision face challenges in accurately calibrating camera pitch and height, especially when used as aftermarket installations, leading to tedious and error-prone processes that can result in poor performance.

Innovation Solution

An automatic calibration method using image sets from multiple perspectives or a single image, where a mathematical model is fitted to the crop rows to determine calibration parameters such as pitch and height, allowing for precise translation of image units to navigational units through homography.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual calibration methods are used for camera pitch and height, then calibration can be performed, but the process becomes tedious and error-prone

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

Solution Approach 1:

The system performs automatic calibration by capturing images of crop rows and computing camera parameters (pitch and height) through image processing and mathematical modeling, eliminating the need for manual calibration operations. The calibration process serves itself by using the captured images to automatically determine the required parameters.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical calibration procedures with an automated computer vision-based system. Instead of physically adjusting and measuring camera parameters manually, the system uses image processing, homography calculations, and mathematical optimization to automatically compute the calibration parameters.

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

2Reliability

If manual calibration procedures are followed, then calibration can be completed, but errors increase and performance deteriorates

Engineering Contradiction:
Improvenavigation system performanceVSAvoidcalibration process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary calibration automatically by capturing images and computing parameters before navigation begins. This preliminary automated calibration ensures accurate camera parameter determination, improving navigation reliability while reducing the complexity of subsequent operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from captured images to iteratively refine calibration parameters. By processing images and comparing results with expected geometric relationships, the system automatically adjusts and optimizes camera pitch and height values, improving reliability while maintaining manageable complexity.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If automatic calibration using image sets is implemented, then calibration accuracy improves, but processing complexity increases

Engineering Contradiction:
Improvecamera parameter accuracyVSAvoidcalibration algorithm complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The calibration process is segmented into distinct stages: image capture, feature detection (identifying crop row positions), homography calculation, and parameter optimization. This segmentation allows the complex task to be broken down into manageable steps, improving accuracy while controlling overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The calibration system serves multiple functions: it captures images, detects crop row geometry, computes homography transformations, and determines camera parameters. This multi-functionality consolidates what would otherwise require separate systems into a unified calibration process, improving accuracy without proportionally increasing complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentUS11659783B2Calibrating crop row computer vision system
Publication Date: 2023.05.30 RAVEN INDUSTRIES INC
  • US11659783B2 patent drawing
  • US11659783B2 patent drawing
  • US11659783B2 patent drawing

AI summary

System and techniques for calibrating a crop row computer vision system are described herein. An image set that includes crop rows and furrows is obtained. Models of the field are searched to find a model that best fits the field. A calibration parameter is extracted from the model and communicated to a receiver.