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How to Set Up Tracking Systems in Aximmetry
About the Concept of Camera Calibration
Introduction
The Camera Calibrator is included in the Broadcast & Film Edition and can also be purchased for other editions.
The Aximmetry Calibrator offers you 2 types of calibrations:
- The Lens Calibration deals with lens distortion and calculates the Focal Length.
- The Tracking Calibration automatically calculates the Tracker's transformation and rotation.
The application has built-in guidance; no external How-To documentation is needed.
The Camera Calibrator currently supports the calibration of two types of tracking systems:
6DOF: 6 Degree-of-Freedom tracking systems.These are the standard tracking systems capable of providing position and rotation data.
PTZ: short for PTZ cameras.
Alternatively, you can also choose to use the Aximmetry Basic Calibrator for calibration. The Basic Calibrator is included in the Broadcast & Film Edition.
For more information on how to use the Aximmetry Basic Calibrator to calibrate your PTZ cameras, please follow this link: Basic Lens Calibration (without lens distortion)
Calibration Board
To perform the camera calibration, you will need two special images printed on a stiff board.
You can download the two images using this link: Calibration_boards.
Maybe you will need only the big checkerboard (the one with 5x5 cm squares) for the calibration process, still, we recommend printing both of them to have all the equipment possibly necessary for a successful calibration.
Aximmetry Camera Calibrator in use with the camera pointing to the calibration board on a chair:
Recommendations
We recommend you use your local printing service.
We use a 0.5 cm-thick PVC foam board. The size of the board is 55x40cm.
The print should be extremely precise, with at least 0.1mm tolerance.
Do not use any reflective material for the board, as it may negatively impact the calibration process.
NOTE: The images are in a format designed for printing services, so there are margins around the actual image.
You can use two separate boards or you can use two sides of one board. Although not every printing service can print on both sides.
On the actual final board, you should see a checkerboard pattern with 5x5 cm squares and one with 2x2 cm ones.
You should check the final print to see if the size of the pattern is correct. Even if the printing service is precise, there can be a miscommunication about the absolute size of the table.
Buying the Boards from Aximmetry
Alternatively, we can send the board to you. In this case, we would ask you to pay the shipping and production costs of the board.
If you want to go for this option, please let us know at sales@aximmetry.com, and our Sales team will send you a cost estimate.
Starting Calibrator
If you are using the Broadcast & Film Edition of Aximmetry, you will find the Camera Calibrator under Aximmetry Broadcast & Film in the Start Menu.
If you are using the Studio Edition of Aximmetry and purchased the Calibrator, you will find it under Aximmetry Calibrator in the Start Menu.
The Startup Configuration screen is similar to the Composer. Define your outputs if needed.
NOTE: We recommend not mapping your tracking devices here but choosing them later.
Then you must add your first Camera Profile.
As you can see, the Calibrator has presets for many cameras. If your device is not listed, choose Custom and type your camera sensor's width.
Now you must set your Tracking Device and Video Input. Setting up a Zoom Device is needed only if you use a stand-alone Zoom encoder device.
After clicking on Calibrate Lens, the built-in guide will help you pass through the process.
Applying Calibration Results in Aximmetry Composer
When using Tracked Camera compounds in Aximmetry, go to the INPUTS Control Board. Select the INPUT 1 panel to set up your Camera device and Tracking Device, and select the camera calibration in the Calibration Profile.
Calibration Tips
Here we have some tips that could help you achieve a better calibration.
- Aperture setting: Try using an aperture range from T4 / F4 - T12 / F12.
- An aperture number lower than that could have a very shallow DoF and the camera image may not be sharp enough for the calibration.
- An aperture number higher than that could cause diffraction and require a higher ISO / Gain making the image noisier and not useable for the calibration.
- Light the board as evenly as possible with diffuse light to avoid any specular reflection
- If you find that there is still too much specular reflection, you can try to light the board from the camera's side so the light won't bounce into the camera from the board.
- You may move the light around as long as it results in an evenly lit board.
- ISO setting: Try shooting at the lowest ISO possible, or if your camera has a native ISO, use that
- If your camera has dual-native ISO we suggest using the lower one if possible.
