Automatic Lens Distortion Correction
Every lens bends the image a little, which can curve lines that are straight in real life. Automatic Lens Distortion Correction fixes this, so the picture matches what the camera actually saw. This article covers how to calibrate it.
Preparing the Aruco board
First, prepare your Aruco board in one of two ways:
Printed board: Print the PDF, at home or at a print shop, and mount it on a stiff surface like cardboard so that it is completely flat.
Tablet: Open the Aruco board PDF on a tablet, ideally the size of a standard iPad or larger.
The Aruco board is available as a PDF file .
Step-by-step calibration guide
Step 1: Prepare the Aruco board
Prepare your Aruco board using one of the methods above.
Step 2: Open the Calibration tab
- Open Swing Catalyst.
- Open Settings, either from the start menu or from the main menu button in analysis mode, and go to Cameras.
- Click Advanced… on the camera you want to calibrate. The Advanced Camera Settings dialog opens.
- Click the Calibration tab.
Step 3: Start the calibration
Press the Start calibration button.
Step 4: Perform the calibration
Watch the two figures: As you move the Aruco board, watch the Coverage: percentage and the Calibration error: value. Move the board: Gently move and tilt the board across different parts of the camera’s field of view. Aim for these targets: At least 80% coverage and a calibration error below 1. These are the targets the software itself suggests on the Calibration tab. Keep going until you reach them: Keep adjusting the board’s position until both figures are in range.
Step 5: Complete the calibration
Stop the calibration: Once coverage and calibration error are in range, click Stop calibration. The software applies the correction: It calculates the correction and applies it to the camera. Check the result: Look at the live image to confirm that straight lines now look straight.
Tips for a good calibration
Smooth, slow movements: to avoid blur. Cover the whole view: move the board through the entire field of view, including the corners. Vary angles and distances: tilt and rotate the board so the camera sees it from different perspectives. Good lighting: calibrate in a well-lit room to avoid shadows and reflections on the board.
Result
Following these steps and reaching good coverage and a low calibration error gives you a calibrated camera with corrected video.