Automated assembly and quality control require reliable systems for the detection of the position and the orientation of complicated objects. Correlation methods are well suited, but they are affected by structured backgrounds, varying illumination conditions, and textured or dirty object surfaces. Using fringe projection to exploit the three-dimensional topography of objects, we improve the performance of a nonlinear joint transform correlator. Positioning of noncooperative objects with subpixel accuracy is demonstrated. Additionally, the tilt angle of an arbitrarily shaped object is measured by projection of object-adapted fringes that produce a homogeneous fringe pattern in the image plane. An accuracy of better than 1° is achieved.
© 1998 Optical Society of America
(070.1170) Fourier optics and signal processing : Analog optical signal processing
(070.4340) Fourier optics and signal processing : Nonlinear optical signal processing
(070.4550) Fourier optics and signal processing : Correlators
(070.5010) Fourier optics and signal processing : Pattern recognition
(100.2650) Image processing : Fringe analysis
Tobias Haist, Martin Schönleber, and Hans J. Tiziani, "Positioning of Noncooperative Objects by use of Joint Transform Correlation Combined with Fringe Projection," Appl. Opt. 37, 7553-7559 (1998)