Three-dimensional reconstruction of wear particle surface based on photometric stereo

Ferrography has emerged as a significant candidate for the provision of relevant information for the determination of the status of machine wear. However, this conventional methodology provides only marginal results due to its inability to provide 3-dimensinal (3D) surface information. The authors of this paper have developed a methodology based on photometric-stereo towards the enhancement of the capabilities of ferrography. This enhanced and innovative methodology consists of three main components, the multi-illumination image acquisition, the wear particle extraction, and the 3D surface reconstruction. The methodology ensures the reliable and efficient extraction of the wear particles surface topographies for further feature-based wear particle identification. The performance of this methodology has been compared with results observed from the laser scanning confocal microscopy. The outcome of this comparison has depicted that the methodology involving this new low-cost ferrography system exhibits very high accuracy for the 3D surface feature extraction of wear particles.