US 11,704,832 B2
Camera calibration and/or use of a calibrated camera
Martin Schrader, Tampere (FI); Radu Ciprian Bilcu, Tampere (FI); and Adrian Burian, Tampere (FI)
Assigned to Nokia Technologies Oy, Espoo (FI)
Appl. No. 16/975,939
Filed by Nokia Technologies Oy, Espoo (FI)
PCT Filed Mar. 14, 2018, PCT No. PCT/IB2018/051708
§ 371(c)(1), (2) Date Aug. 26, 2020,
PCT Pub. No. WO2019/175629, PCT Pub. Date Sep. 19, 2019.
Prior Publication US 2020/0402260 A1, Dec. 24, 2020
Int. Cl. G06T 7/80 (2017.01); G06T 7/50 (2017.01)
CPC G06T 7/80 (2017.01) [G06T 7/50 (2017.01); G06T 2207/10028 (2013.01)] 19 Claims
OG exemplary drawing
 
1. An apparatus, comprising:
at least one processor; and
at least one non-transitory memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform:
capturing an image of a calibration pattern comprising features defining object points;
determining, from the image, measured image points that correspond to the object points;
determining, from the mapping, putative image points that correspond to the object points; and
minimizing a cumulative cost function dependent upon differences between the measured image points and putative image points to determine parameters of the parametric mapping;
wherein the mapping uses a parametric function to specify points where light rays travelling from object points to image points cross an optical axis;
wherein the parametric function is a non-linear function of an angle the light ray travelling from an object point towards an image point makes with the optical axis as it crosses the optical axis.