Method for constructing a continuous design space for generating a physical property model in a faulted subsurface medium. The matching relationship of the fault traces on the two sides of each fault is used in a systematic way to determine the location of the fault traces in the design space. The location of any other point in the design space may then be determined by interpolation of the locations of fault traces. The fault traces are thus used as control points for the mapping. The method involves: (a) identifying the control points and determining their location in both physical and design space and (b) using selected control points, mapping any point from physical space to design space, preferably using the moving least squares method.