Digital fringe projection is a non-contact method that is widely used for the dimensional characterisation of complex manufactured parts. However, single camera-projector fringe projection systems struggle to acquire the full three-dimensional point cloud in one acquisition due to their relatively small field-of-view, and the typically freeform geometry, potentially with multiple occlusions, of additively manufactured parts. In this paper, we demonstrate that a multi-view fringe projection system is an effective solution to address form measurement of complex additively manufactured parts. However, the global geometric characterisation of multiple sets of cameras and projectors is a challenge due to the lack of a common field-of-view and overlapping of the projected fringes. We use a cost-effective multi-view fringe projection system to characterise an assembly of multiple sets of cameras and projectors with different perspectives. We present an automated characterisation method that uses a checkerboard which is moved in the measurement volume. The absolute phase information from the captured phase-stepped images is used to establish the global geometric properties by automated image processing and parameter optimisation. The geometric characterisation method is implemented and the multi-view system has been used to measure a range of additive parts. In this paper, we present the three-dimensional reconstruction results from different views that are combined to optimise the global geometric parameters.
Leach, R. K., Shaheen, A., Piano, S., Sims-Waterhouse, D., & Bointon, P. (2019). Automated characterisation of multi-view fringe projection system for three- dimensional measurement of additively manufactured parts