The optical geometry of the Fourier transform profilometry (FTP) which do not have coplanar and parallel limitations is analyzed through two different reference planes,and a fictitious exit pupil of the projector is introduced. The corresponding phase-height mapping is given based on ray tracing,a method to estimate the parallelism is proposed. The camera coordinate system is applied to fulfill the calibration of the height and the lateral coordinates. Experiment results show the effectiveness and feasiblity of the proposed method.