  The key to accurate 3D shape measurement in Fringe Projection Profilometry
(FPP) is the proper calibration of the measurement system. Current calibration
techniques rely on phase-coordinate mapping (PCM) or back-projection
stereo-vision (SV) methods. PCM methods are cumbersome to implement as they
require precise positioning of the calibration target relative to the FPP
system but produce highly accurate measurements within the calibration volume.
SV methods generally do not achieve the same accuracy level. However, the
calibration is more flexible in that the calibration target can be arbitrarily
positioned. In this work, we propose a hybrid calibration method that leverages
the SV calibration approach using a PCM method to achieve higher accuracy. The
method has the flexibility of SV methods, is robust to lens distortions, and
has a simple relation between the recovered phase and the metric coordinates.
Experimental results show that the proposed Hybrid method outperforms the SV
method in terms of accuracy and reconstruction time due to its low
computational complexity.
