Preparing a calibration target

Calibration requires preparation of a physical calibration target. The attention paid to preparing the target correctly will result in a more accurate outcome for your artoolkitX-based tracking.

The key requirements are:

1. Print the calibration target on a printer with high-contrast output, preferably a laser printer.
2. Print the calibration target at 100% scale, so that the square sizes or circle-separations are exactly the same as in the PDF.
3. If possible, print using the largest size available (A3 metric paper size or Tabloid US paper size.) These provide many more calibration points in each image.
4. Affix the printed calibration to a perfectly flat surface, e.g. a piece of stiff flat wood board.

If you are using the mobile apps, printing of either the A4 or US Letter size square pattern is available directly in the app, or they can be found here:

• Calibration chessboard (5 x 7 corners, 30mm spacing) A4 paper size
• Calibration chessboard (5 x 7 corners, 30mm spacing) US Letter paper size
• Calibration chessboard (11 x 17 corners, 20mm spacing) A3 paper size
• Calibration chessboard (11 x 17 corners, 20mm spacing) Tabloid paper size
• Calibration asymmetric circles (4 x 11 circles, 20mm spacing) A4 paper size
• Calibration asymmetric circles (4 x 11 circles, 20mm spacing) US Letter paper size
• Calibration asymmetric circles (6 x 17 circles, 20mm spacing) Tabloid paper size
• Calibration asymmetric circles (6 x 17 circles, 20mm spacing) Tabloid paper size

Once the pattern is printed, measure carefully with an accurate ruler to check that the pattern size is as expected. For example, squares on the small chessboard should be exactly 30mm wide, and on the large chessboard they should be exactly 20mm wide:

Example of large pattern affixed to board:

Example of small pattern fixed to board: