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Version: Traxis Camera Tracking 2.3

FL / NO

In an ideal lens, the position of objects in the image is defined by two main parameters: Focal Length (FL) and Nodal Offset (NO).

Calibration of these parameters focuses on objects near the center of the image, where lens distortion is minimal and can be ignored.
This approach helps determine accurate FL and NO values.

FL vs NO
  • FL (Focal Length): Affects both near and far markers equally.
  • NO (Nodal Offset): Affects all markers as well, but has a much stronger effect on nearby objects and a weaker effect on distant ones.

Calibration Steps​

  • Center on the Far marker: Position the camera so that the physical and virtual Far markers overlap at the center of the image.

Panning the camera

  • Pan the camera slightly to the left: Keep the marker near the center. After panning, the Far markers will no longer overlap, as illustrated above.

Adjusting FL

  • Adjust FL (Focal Length): Change the FL value until the Far marker aligns again, as shown above. This adjustment also affects the Near marker slightly, but it may not line up perfectly yet.

  • Adjust NO (Nodal Offset): Change the NO value until the Near marker aligns as well. Because NO mainly affects nearby objects, this step will fine-tune the Near marker but also slightly influence the Far marker.

Adjusting NO

  • Repeat steps 3 and 4 a few times until both markers are properly aligned, as shown above.