Theory of moiré sensing by means of contour functions

Harthong, J.; Sahli, Hichem

doi:10.1364/ao.31.001436

Cited by 3 publications

(2 citation statements)

References 3 publications

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“…The mathematical approach refer to a previous paper [1] Let (s. t) be the contour function of the projected grating (it constitutes the unknown data we are seeking for) ; s, t are the two coordinates in the plane of this grating. Computing the specific grid (mathematical analysis).…”

Section: Introductionmentioning

confidence: 99%

“…Now let us describe the way of computing this specific grid. onto the object (within the frame of the instrument) will have space coordinates x, y, z = ho(x, y), where the function h0 describes the object shape, and will be for these functions, but they can be computed numerically as described in [1] • From the superposition of the two grating structures which produce the moire effect, we have Further, let W(tt, v) be the contour function of the reference grating ; u, v are the two coordinates in the plane of this grating.…”

Section: Introductionmentioning

confidence: 99%

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<title>Inverse moire</title>

Harthong¹,

Becker²

1997

SPIE Proceedings

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The usual moire method consists in projecting a grid, that is made of parallel straight lines, onto an object. Then a moire picture is obtained, which is made of curved fringes. In the inverse moire method, we compute a specific grid that is made of straight fringes. The object must be known, but small deformations from a known mean shape can be analysed with very simple fringe processing. We show some examples ofreconstruction by inverse moire.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

<title>Inverse moire</title>

Harthong¹,

Becker²

1997

SPIE Proceedings

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Positioning of noncooperative objects by use of joint transform correlation combined with fringe projection

1998

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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 degrees is achieved.

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Farbkodierte objektangepasste Streifenprojektion für die schnelle 2D- und 3D-Qualitätsprüfung (Color-coded Object-adapted Fringe Projection for Two- and Threedimensional Quality Control)

Haist¹,

Tiziani²

2002

Teme

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Die Kontrolle von Werkstücken hinsichtlich ihrer dreidimensionalen Geometrie und ihrer Oberflächencharakteristik ist von entscheidender Bedeutung für die automatisierte industrielle Produktion. Vorgestellt wird ein schnelles und robustes Einzelbildverfahren, das es gestattet, gleichzeitig die Topographie zu kontrollieren und ein Videobild des Werkstückes zu generieren. Hierzu wird eine objektangepasste Streifenprojektion mit einer farbkodierten Maske verwendet. Zur Detektion können preiswerte Einzelchip-Farbkameras zum Einsatz kommen. Das Verfahren erzielt eine vergleichsweise gute 3D-Auflösung von 1/4000 bei einer hohen lateralen 2D-und 3D-Auflösung und ist weitgehend unempfindlich gegen lokale Verschmutzungen und Variation der Beleuchtung.Industrial quality control requires fast and robust detection of the topography as well as the surface of objects. We present a fast single-frame method based on object-adapted fringe projection where a color mask is used in order to simultaneously obtain a video image as well as a map of the deviation of the topography. Color-coded projection in combination with detection by a consumer one-chip digital camera is employed for testing complex objects by simple means. An accuracy of 1/4000 in 3D together with a high lateral resolution is obtained. Additionally the method is quite immune against dirt and varying illumination conditions.

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Theory of moiré sensing by means of contour functions

Cited by 3 publications

References 3 publications

<title>Inverse moire</title>

<title>Inverse moire</title>

Positioning of noncooperative objects by use of joint transform correlation combined with fringe projection

Farbkodierte objektangepasste Streifenprojektion für die schnelle 2D- und 3D-Qualitätsprüfung (Color-coded Object-adapted Fringe Projection for Two- and Threedimensional Quality Control)

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