Documentation

Geometric Calibration

Introduction

Geometric calibration is the process of estimating the parameters required to relate (2-D) points in a camera’s image plane with (3-D) points in the world scene the camera is viewing. With a calibrated camera each point on a sensor translates into a ray emanating into the scene, providing directional information about points in a scene. 

Moreover, with a pair of calibrated cameras (typically called a stereo pair) it is possible to triangulate distances and make estimations of the distance to points in the world. Determining geometry from multiple views (either from multiple cameras or multiple frames from one) is the at the heart of classical computer vision. 

 

Getting started with the Geometric Calibrator

The Geometric Calibrator module in Imatest Master and IT is the software portion of Imatest’s geometric calibration solution.

However, calibration is not a software-only problem- it first requires a physical target setup. The more stringent the calibration accuracy requirements, the greater the demands on the physical setup and the number of images required.

It is recommended that new users of the Geometric Calibrator module proceed by:

  • Read through the requirements to understand what evidence the Geometric Calibrator needs and how to design a test setup accordingly
  • Contact us about designing a calibration solution accordingly 
  • Consult the terminology pages to clarify the many details of the language of calibration (units and coordinate systems)
  • Learn how Imatest defines the components of Calibration Tasks
  • Familiarize yourself with the software operation, either Imatest Master’s GUI or Imatest IT’s programmatic interface

 

Calibration Consultation

In order to achieve the highest accuracy calibrations that this module can produce, it is highly recommended that you communicate with us before embarking on creating a calibration test setup.

Every calibration project tends to be different due to field of view, working distance, combination of cameras, etc., and even issues like choosing the appropriate checkerboard size and pitch require consideration. We have found that we are able to achieve extremely high accuracy even for challenging camera systems (including simultaneous extremely-wide-FoV and telephoto multi-cam systems), but that designing and verifying an appropriate test setup requires significant design work. 

For high precision needs or challenging testing scenarios (such as on a production line with limited space), expert planning and validation becomes vital. Initial inquiries are welcome at support@imatest.com. Comprehensive solutions are available through contract consulting

 

Requirements Software operation Defining Calibration Tasks Definitions and Theory

Supported Systems

Supported Targets

Required Evidence

Test Setup

Calibration Procedure

Use in Imatest Master

Use in Imatest IT

Module settings

Module outputs

Defining a Device

Defining Distortion

Defining the System of Devices

Defining the Target

Defining a Test Capture

Defining a Test Image

Homogenous Coordinates

Projective Camera Model

Multi-Camera Systems

Distortion Models

Coordinate Systems

Rotations and Translations