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Camera re-calibration after zooming based on sets of conics


We describe a method to compute the internal parameters (focal and principal point) of a camera with known position and orientation, based on the observation of two or more conics on a known plane. The conics can even be degenerate (e.g., pairs of lines). The proposed method can be used to re-estimate the internal parameters of a fully calibrated camera after zooming to a new, unknown, focal length. It also allows estimating the internal parameters when a second, fully calibrated camera observes the same conics. The parameters estimated through the proposed method are coherent with the output of more traditional procedures that require a higher number of calibration images. A deep analysis of the geometrical configurations that influence the proposed method is also reported.

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Correspondence to Alberto Alzati.

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Frosio, I., Turrini, C. & Alzati, A. Camera re-calibration after zooming based on sets of conics. Vis Comput 32, 663–674 (2016).

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  • Camera calibration
  • Conics
  • Degenerate conics
  • Ellipses
  • Zoom lens
  • Line detection