surface_to_grid3d: Interpolate grid(df) to 3D grid
In marcianito/hygra: Processing of HydroGravimetry data

interpolate DEM to necessary grid of corresponding layer

1	surface_to_grid3d(surface_grid, grid_discr, depth_split, Bd_x, Bd_y)

`grid_discr`	vector of discretization of new grid in (x,y,z).
`Bd_x, y`	Vector, containing min and max coordinates of buildings x and y coordinates. They only need to be supplied, if no surface grid is given as input.
`grid_cords`	coordinates of the original hydrus mesh.
`data_input`	data to be interpolated. in fomat of the hydrus mesh.