Accurate projector calibration method by using an optical coaxial camera

Abstract

Digital light processing (DLP) projectors have been widely utilized to project digital structured-light patterns in 3D imaging systems. In order to obtain accurate 3D shape data, it is important to calibrate DLP projectors to obtain the internal parameters. The existing projector calibration methods have complicated procedures or low accuracy of the obtained parameters. This paper presents a novel method to accurately calibrate a DLP projector by using an optical coaxial camera. The optical coaxial geometry is realized by a plate beam splitter, so the DLP projector can be treated as a true inverse camera. A plate having discrete markers on the surface is used to calibrate the projector. The corresponding projector pixel coordinate of each marker on the plate is determined by projecting vertical and horizontal sinusoidal fringe patterns on the plate surface and calculating the absolute phase. The internal parameters of the DLP projector are obtained by the corresponding point pair between the projector pixel coordinate and the world coordinate of discrete markers. Experimental results show that the proposed method can accurately calibrate the internal parameters of a DLP projector.

Homography based identification for automatic and robust calibration of projection integral imaging displays

“…However, their approach requires the use of fiducial points on a diffuse screen, which are both unsuitable for a see-through display. Calibration can also be done by projecting a virtual pattern on a flat diffuse surface that may contain a calibration pattern [12][13][14]. In this case, the surface also needs to be moved around to obtain an accurate estimation of the parameters.…”

A Structured Light RGB-D Camera System for Accurate Depth Measurement

“…Scharstein et al [11] proposed a method for acquiring high-complexity stereo image pairs with pixel-accurate correspondence information using structured light. Some previous works such as [12][13][14][15] described various methods to perform 3D reconstruction and obtained some satisfactory results. However, those techniques require to use precalibrated 2 International Journal of Optics…”

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“…By projecting several lines onto the 3D object, the number of measurement points per image increases dramatically, and the scanning distance/time drops accordingly. However, without a coding [4][5][6][7] of the lines or other ways to distinguish between the individual lines, the correspondence problem will limit the density/number of lines on the 3D object. But, if the scanning range becomes sufficiently small other scanning methods, rather than the motor-based methods, can be considered.…”

“…The mechanical scanners are precise but consume relatively high amounts of power, emit electrical noise, cause mechanical vibrations and wear down over time. Of non-mechanical options, DLP projectors [6,7] and MEMS mirrors [8] can be mentioned. However, mechanical scanners, displays and projectors are all expensive devices.…”