Many kinds of 3 D profilometry share the drawbacks of not having enough measuring range (especially, when a big object to be tested) and existing shadow problems. A new approach is purposed, which can fit the measurement of big objects and small ones with complicated shape. The theory of spatial coordinate transformation into the 3 D profilometry is presented and the method to transform the phase information into the height of objects and to combine the results from different systems is described.