A fringe analysis technique is proposed to automatically measure 3-D object shape. A grating pattern is projected onto an object, and the grating pattern deforms in accordance with the 3-D object. This deformed grating image is analyzed by means of the subfringe integration algorithm (SIA), in which the phase is retrieved using N bucket integration. Only one frame of the image is sufficient to obtain the phase distribution and the object shape at every pixel on measured object. Theoretical analysis, experimental results, and simulation calculations are presented.