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Version: Traxis Camera Tracking 2.3

Calibration

Now that you have a solid setup, you can calibrate the lens parameters.

Calibration In 3 Steps​

  1. At Zoom = 0, determine FL, NO, K1, K2, FB.
  2. Zoom in one step (0.10 or 0.20), re-determine the above, and additionally any CS. Repeat until zoom = 1.00.
  3. When completed, go back to lower zooms, check for inconsistencies, iterate, fine-tune, and add additional sample points if necessary.

Terminology Refresh​

  • FL (Focal Length): Controls the field of view.
  • NO (Nodal Offset): Controls the position of the entrance pupil. NO is the distance between the entrance pupil and the camera (sensor plane for broadcast cameras, and the pivot point for PTZ cameras).
  • K1/K2: The radially symmetric (i.e., depending on radius) component of lens distortion (squeeze and/or expand the image near the edges).
  • P1/P2: The asymmetric component of lens distortion (squeeze and/or expand the image near the edges). This is ignored by most renderers including Reality 5.
  • CS (Center Shift): How much the image shifts when you zoom in. This should normally be zero, but imperfections in the lens and the lens mount often cause a shift in position. We take a simplified CS approach and assume that CS is 0.0 when fully zoomed out.
  • FB (Focus Breathing): The changes in the parameters above as the focus changes. Mostly visible on Focal Length, but may affect others as well.