A frequency-sweeping technique is proposed to measure the shape of objects with discontinuous height steps and/or spatially separated surfaces, which have been impossible to measure with conventional shadow moire´ topography. By controlling the rotation angle of the grating, spatiotemporal moire´ patterns are produced with different contour intervals. The Fourier-transform technique has been applied to analyze these patterns and obtain the temporal carrier frequency, to which the height distribution of the object is related. Experimental results show the validity of this method. © 2001 Society of Photo-Optical Instrumentation Engineers.