4. Sub Function Descriptions: undistortUV

• undistortUV

  • Description:

  This function undistorts distorted UVd coordinates using distortion models from from the Caltech lens distortion manuals. This function is solving distortUV backwards essentially. However, if one looks at distortUV, it becomes very difficult to untangle all of the coefficients to solve for undistorted camera coordinates x and y. In fact, there is no analytical inverse distortion equation. So we solve for it iteratively. Aggregate Distortion coeffcients fr, dx, and dy should be solved for with undistorted camera coordinates x and y. However, we will solve for them using distorted xd and yd, and then use fr,dx, and dy to to solve for x and y. Then, the new x and y will be used to calculate fr, dx, and dy until the difference between subsequent fr,dx,and dy solutions are less than .001%. Then the final dx,dy, and fr will be used to solve for undistorted U,V. See Section 6 for intrinsics and coordinate system definitions. Notes on distortion model can be found in Section 5; function cannot handle fish-eye lenses.

  • Input:

  Variable	Size	Description
  intrinsics	[1x11]	Intrinsics Vector Formatted as in A_formatIntrinsics.
  Ud	[Px1]	Distorted U coordinates for P points
  Vd	[Px1]	Distorted V coordinates for P points

  • Output:

  Variable	Size	Description
  U	[Px1]	UnDistorted U coordinates for P points
  V	[Px1]	UnDistorted V coordinates for P points

  • Required Core Sub-Functions:

    None.