In the sonar imaging, and more generally in the seafloor remote sensing, researches go forwards fusion systems. Nowadays, it is well-known that starting of the Sonar images, the Digital Elevation Maps (DEMs), can be generated exploiting either the amplitude or the phase of the acoustic signal. In this work, our interest is to generate a complete Digital Elevation Map (DEM)of the seafloor by fusion of two DEMs generation by two different techniques. We aim in this work to elaborate a general system of interpretation that coherently links works on data selection and fusion DEMs, in order to generate useful DEM and exploit it in the seafloor remote sensing application, particularly for the inhomogeneous scene with a variety terrain. In this paper only Shape from Shading and the Interferometry are considered. The first part, describes the generation of Digital Elevation Map (DEM) of the seafloor with Shape from Shading technique, in addition its main characteristics of our procedure implemented. In the second part, we validate our previous DEM generated of Shape from Shading over a test area using a reference DEM obtained by Interferometry processing. In this way it is possible to compare the performances of the two DEMs and to investigate their complementarity. In the last part, a new fusion operators are then defined in order to build DEM using for the seafloor remote sensing applications. We conclude this paper with the first results and online some further works.