Phase coded method with four patterns based on Inverse cosine
2022-01-0317
03/29/2022
- Event
- Content
- Fringe projection profilometry has developed into a technology that widely measures the 3D shape of objects. It can obtain the three-dimensional contour of the object via phase information. As the phase obtained by phase demodulation methods is wrapped within the (−π, π) interval, phase unwrapping becomes one of the critical steps of 3D shape measurements. Most phase-unwrapping algorithms can be classified into two categories: temporal phase unwrapping and spatial phase unwrapping. The temporal phase unwrapping algorithm is more attractive than the spatial phase unwrapping algorithm to measure the discontinuous and spatial isolation shape. However, the temporal phase unwrapping algorithm needs to project and capture many fringe patterns. Nowadays, Cai et al. encode a specific codewords’ sequence to get the fringe order by 3 adjacent codewords, which increases the fringe order. In the paper, we proposed a phase-coded method with four patterns based on Inverse cosine. We project and capture a set of three-step phase-shift sinusoidal fringe patterns and a cosine pattern encoding stair phase, and then we compute the wrapped phase, modulation, and background components from the sinusoidal fringe patterns, normalized cosine pattern can be estimated via the cosine pattern, modulation and background components, inverse cosine calculation is applied to obtain the stair phase, then the fringe order is determined from the stair phase. a semi-periodic fringe order correction algorithm based on dilation is proposed to ensure the accuracy of fringe order. The continuous phase is obtained from the wrapped phase and the fringe order. Experiments are then carried out to verify the performance of the proposed method using a face model and hollow foam board as specimens. The results show that our algorithm can achieve accurate three-dimensional(3D) measurement with only four patterns.
- Citation
- ding, y., "Phase coded method with four patterns based on Inverse cosine," SAE Technical Paper 2022-01-0317, 2022, .