A single shearing interferogram is not sufficient to describe a wavefront. Two interferograms sheared in orthogonal directions must be used to reconstruct the wavefront of any arbitrary shape. Two types of two dimensional lateral shearing interferometers have been studied: orthogonal shearing prism and crossed grating. A method is described that uses data obtained from the interferograms to reconstruct the wavefront. It was used in processing the interferograms obtained in our experiment.