We first provide an overview of 3-D shape measurement us- ing various optical methods. Then we focus on structured light tech- niques where various optical configurations, image acquisition tech- niques, data postprocessing and analysis methods and advantages and limitations are presented. Several industrial application examples are presented. Important areas requiring further R&D are discussed. Finally, a comprehensive bibliography on 3-D shape measurement is included, although it is not intended to be exhaustive. © 2000 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(00)00101-X)

Overview of three-dimensional shape measurement using optical methods

Temporal phase unwrapping algorithms for fringe projection profilometry: A comparative review

Optical Methods for Dimensional Metrology in Production Engineering

Multisensor data fusion in dimensional metrology

Quality-guided phase unwrapping is a widely used technique with different quality definitions and guiding strategies reported. It is thus necessary to do a detailed comparison of these approaches to choose the optimal quality map and guiding strategy. For quality maps, in the presence of noise, transform-based methods are found to be the best choice. However in the presence of discontinuities, phase unwrapping is itself unresolved and hence quality-guided phase unwrapping is not sufficient. For guiding strategies, classical, two-section, and stack-chain guiding strategies are chosen for comparison. If accuracy is the foremost criterion then the classical guiding strategy with a data structure of indexed interwoven linked list is best. If speed is of essence then the stack-chain guiding strategy is the one to use.

Quality-guided phase unwrapping technique: comparison of quality maps and guiding strategies

A new concept for 3-D shape measurement of complex ob- jects is proposed, which is based on photogrammetry and fringe projec- tion. The shape of a partial view is determined by a combination of the phase-shift method for fringe evaluation and a photogrammetric triangu- lation to calculate the 3-D coordinates related to the sensor coordinate system. For the measurement of complex objects, partial views are taken from different sensor positions. The problem of matching the par- tial views into each other is solved by transforming each sensor position and the relating point cloud of the shape in a global coordinate system by photogrammetric matching of reference targets. © 2000 Society of Photo- Optical Instrumentation Engineers. (S0091-3286(00)02701-X)

3-D shape measurement of complex objects by combining photogrammetry and fringe projection

3D-measurement systems based on active triangulation using projection of structured light and recording by CCD-cameras are gaining more and more importance in industrial application. Their advantages compared to conventional coordinate measurement machines are the non-contact measurement and the fast acquisition of dense point clouds. This paper presents an alternative method to the well-known combination of Graycode and phase-shift projection. It will be shown how to use the heterodyne principle for overcoming the unwrapping problem of phase functions and for estimating the parameters for a reliable unwrapping procedure. The redundant phase information is used to increase the accuracy of the photogrammetrical 3D-coordinate determination. Finally, the heterodyne principle is used to realize on-line measurement based on color-coded fringe projection.

White light heterodyne principle for 3D-measurement

The process of micro assembly requires high precision and accuracy for the positioning of micro parts. Therefore a demand exists for very precise and accurate handling devices with a specific focus on positioning devices. This paper presents an approach using robots based on closed kinematic chains, so called parallel robots, to achieve high precision in automated micro assembly. The discussion continues on a calibration process for parallel robot structures to increase the accuracy of the robot system. However obtaining an accuracy in the range of submicrometer requires an additional sensor controlled positioning process. Hence the paper presents an approach using visual control. That approach includes the application of area based matching techniques as well as photogrammetric calibration of the camera system to increase the accuracy within the image processing.

Visual control and calibration of parallel robots for microassembly

3D measurement systems based on active triangulation using projection of structured light and recording in CCD- cameras are gaining more and more importance in industrial applications. Their advantages compared to conventional coordinate measurement machines are the non-contact measurement and fast acquisition of dense point clouds.

Carsten Reich

Papers

3-D shape measurement of complex objects by combining photogrammetry and fringe projection

White light heterodyne principle for 3D-measurement

Visual control and calibration of parallel robots for microassembly

Photogrammetrical matching of point clouds for 3D measurement of complex objects