A Robust and Accurate Calibration Method for Out-of-focus Camera

Abstract

Conventional camera calibration methods regard camera as ideal pinhole model and require well-focused images, which can't be satisfied for long-range photogrammetry or low depth-of-field lens. In this paper, we propose a novel active calibration method for out-of-focus camera using LCD monitor. Firstly, we estimate the defocus map by the temporal coded binary-shift patterns, which makes our method more accurate. Secondly, based on the defocus map, we encode LCD pixel's coordinates into phase-shift patterns with optimal frequency and step properties, and then deblur captured patterns. Finally, deblurred patterns are decoded to generate dense phases map to extract accurate feature points coordinates. Our method significantly improves camera calibrations robustness to lens' defocus, noises, glass refraction compared with state-of-art methods. Experimental results demonstrate that our method is superior to conventional methods whether camera is in-or out-of-focus.

A comparison of an RGB-D cameras performance and a stereo camera in relation to object recognition and spatial position determination

“…Intrinsic and extrinsic parameters of Kinect camera are found according the calibration procedure described in [27], where an image that works as a pattern with known conditions (usually a chess board) is employed to generate relationships of real world (X W , Y W , Z W ) in meters with coordinates in the image. K matrix is important during the calibration procedure, regardless correction factor s, equation 5 is presented.…”

“…Julian S. Rodriguez. / Electronic Letters on Computer Vision and Image Analysis 20(1):[16][17][18][19][20][21][22][23][24][25][26][27] 2021 …”