An effective method for mapping out-of-plane displacements of deformed bodies using moiré interferometry is proposed. By applying the spatial filtering technique two plane reference beam interferograms of the composite diffraction orders are obtained with the spatial carrier of opposite sign. Spatial superimposition of the interferograms results in moiré fringes depicting out-of-plane displacements with half a wavelength sensitivity. Either the uniform field or finite fringe detection mode can be used. Simulation experiments are presented to verify the principles.