The registration process forms an important step in the integration of Digital Elevation Models (DEMs) of resolution. DEM registration invariably involves what is effectively an 'image matching' process utilising similarity number of prospective image matching approaches, Mutual Information (MI) offers potential for application to has proven to be a robust and accurate method of image registration, especially in the field of medical imaging. variation within the terrain models potentially limits the utility of MI for the matching of multi-resolution investigates the potential of MI for DEM registration, and proposes an improved Gradient-based MI (GMI) in applied to raster DEMs where the elevation value at each grid point is replaced by the surface gradient magnitude Experimental results demonstrate that MI-based methods can outperform the often employed Cross Correlation Furthermore, the GMI approach has been found to produce a more accurate and robust registration than MI.