Camera Calibration Using Vertical Markers and Bird's Eye View

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Solution Overview

Problem

Existing camera calibration methods for vehicles require extensive space and cumbersome setup, as they necessitate arranging calibration targets on the road surface or precise physical fixation of targets and vehicles, which complicates the measurement process.

Innovation Solution

A calibration method using vertically or horizontally positioned markers above the road surface, where images are captured, converted into bird's eye view, and camera parameters are calculated based on marker positions, eliminating the need for extensive space and precise positional relationships.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If calibration targets are placed on the road surface in a predetermined positional relationship, then measurement accuracy is improved, but the measurement space required becomes several times larger than the vehicle space

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmeasurement space
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent transitions from placing calibration targets on the road surface (2D plane) to suspending them vertically in space (3D space). By utilizing the vertical dimension and positioning targets at different heights above the road surface, the system achieves accurate calibration without requiring extensive horizontal measurement space, thus resolving the contradiction between measurement accuracy and space requirement.

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

Solution Approach 2:

The patent changes the positional parameters of calibration targets from horizontal arrangement on the road surface to vertical suspension in air. By adjusting the height parameter and spatial configuration of targets, the system maintains measurement accuracy while significantly reducing the required measurement area.

Inventive Principle:
Principle #35Parameter changes

2Area of stationary object

If targets are arranged vertically at a height from the road surface, then the measurement space is saved, but it becomes necessary to physically fix the vehicle and target or adjust target position using scope means

Engineering Contradiction:
Improvemeasurement spaceVSAvoidmeasurement operation
Core Design Contradiction:
Area of stationary objectVSEase of operation

Solution Approach 1:

The patent replaces mechanical fixation systems (joints, physical mounting) and optical adjustment systems (scope means) with a computational approach. By using image processing and coordinate transformation algorithms, the system determines the positional relationship between the camera and calibration targets without requiring physical fixation or manual adjustment, thus simplifying the measurement operation.

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

Solution Approach 2:

The system performs self-calibration by automatically capturing images of vertically positioned targets and computing the camera's attitude parameters through image processing. The calibration process is autonomous, requiring no manual intervention for physical fixation or position adjustment, making the operation simpler and more efficient.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If joints or scope means are used to establish predetermined positional relationship, then measurement accuracy is maintained, but the device complexity and operational complexity increase

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidcalibration device complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent eliminates mechanical joints and optical scope means by using computational methods. The system captures images of calibration targets and uses image processing algorithms to calculate the camera's attitude parameters, replacing complex mechanical and optical systems with a simpler computational approach that maintains measurement accuracy.

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

Solution Approach 2:

The system creates a digital representation (image) of the calibration targets and uses this copy to compute positional relationships. By working with image data and coordinate transformations rather than physical mechanical systems, the patent simplifies the device complexity while preserving measurement precision.

Inventive Principle:
Principle #26Copying

Data Source

PatentUS10171802B2Calibration method and calibration device
Publication Date: 2019.01.01 DENSO CORP
  • US10171802B2 patent drawing
  • US10171802B2 patent drawing
  • US10171802B2 patent drawing

AI summary

A calibration method for calibrating an attitude of a camera mounted on a vehicle using markers each arranged vertically and each positioned at a pre-designated height from a road surface. The method includes: a first process including shooting an image of the markers with the camera, thereby generating a two-dimensional image; a second process including converting the two-dimensional image into a bird's eye view image on a specific plane so that the bird's eye view image reflects the height of each of the markers; and a third process including calculating a parameter of the camera based on a position difference between the markers in the specific plane obtained in the second process.