We propose a new method of form parameterization. Our methodological exploration led us to begin to apply this method in the field of metrology. This parameterization comes from a discrete modal decomposition (DMD). It is to decompose a signal (for us a part measurement) in a set of discrete functions. This set results from a mechanical vibration computing. Modal metrology of surfaces MemoSurf allows us to expand the writing of surface geometric variations by means of a mathematical language used by all actors in the product life cycle.