lfLensCalibDistortion Struct Reference

Lens distortion calibration data. More...

#include <lensfun.h>

Public Attributes
enum lfDistortionModel	Model
	The type of distortion model used.
float	Focal
	Nominal focal length in mm at which this calibration data was taken.
float	RealFocal
	Real focal length in mm for this nominal focal length. More...
cbool	RealFocalMeasured
	Whether the real focal length was actually measured.
float	Terms [5]
	Distortion coefficients, dependent on model (a,b,c or k1 or k1,k2)

Detailed Description

Lens distortion calibration data.

Lens distortion depends only of focal length. The library will interpolate the coefficients values if data for the exact focal length is not available.

Member Data Documentation

RealFocal

float lfLensCalibDistortion::RealFocal

Real focal length in mm for this nominal focal length.

When Lensfun speaks of “focal length”, the nominal focal length from the EXIF data or the gravure on the lens barrel is meant. However, especially for fisheye lenses, the real focal length generally differs from that nominal focal length. With “real focal length”, Lensfun means the focal length in the paraxial approximation, see http://en.wikipedia.org/wiki/Paraxial_approximation. Note that Hugin (as of 2014) implements the calculation of the real focal length wrongly, see http://article.gmane.org/gmane.comp.misc.ptx/34865.

The default value usually is the nominal focal length. Only for Hugin-based distortion models, the default is the nominal focal length multiplied by the "d" parameter (i.e. linear in r) in the Hugin polynomial. This is because it is this focal length that Hugin assumes in its fit.

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The documentation for this struct was generated from the following file:

• lensfun.h