### 3-D Smooth Surface Plots

I want to plot a smooth 3D surface plot using a matrix of integer numbers.
Presently my 3d plot consist of 12X12 matrix but the plot output is jagged and less appealing. Therefore I would like to smoothen the plot using interpolation/extrapolation or cubic splines method or any other method so that I get a smooth surface plot

Which functions in SAGE can be used for smoothening the surface plots?