Absolute macroscopic 3-D measurements with the innovative depth-scanning fringe projection technique (DSFP)
Abstract:We are presenting a new depth-scanning fringe projection technique (DSFP) on the basis of triangulation for the absolute 3-D measurement of a macroscopic scene. The absolute phase can be determined for any desired depth range of the measurement volume. Furthermore, the known limitations of the depth of focus occurring by light projection techniques, will be overcome. During the measurement procedure, an illuminated Ronchi grating in front of a projection lens is moved both in z- and x-directions by two perpendicularly arranged linear translation stages. This results in an oblique shift of the projected grating, resulting in a oblique scan of the projected fringe pattern in the measurement volume i.e. the object space. For a well-focussed image acquisition, a CCD-camera placed on the same z-stage in front of an observation lens takes a series of images of the scene in different z-positions. This focusing allows the use of large apertures and therefore a better exploitation of light. In our assembled sensor, the triangulation basis of 75 mm approximately corresponds to the distance of a person's pupils.
Document Type: Original Article
Affiliations: Institut für Technische Optik, Universität Stuttgart, Pfaffenwaldring 9, D-70569 Stuttgart, Germany
Publication date: November 1, 2001