This command warps a matrix map to a graticule mesh, which itself is projected according to the map axes property MapProjection. The fineness, or resolution of this grid determines the quality of the projection and the speed of plotting it. There is no hard and fast rule for sufficient graticule resolution, but in general, cylindrical projections need very few graticules points in the longitudinal direction, while complex curve-generating projections require more. h = surfm(map) projects the matrix map map on a graticule grid the size of map between the latitude and longitude limits of the current map axes. The handle h of the displayed surface can be returned. h = surfm(map,npts) results in a graticule grid defined by npts, which is a two element vector of the form [latitude-points longitude-points]. h = surfm(lat,lon,map) allows three other methods of defining the graticule grid. If lat and lon are matrices, they represent the actual graticule vertices as might be returned by meshgrat. If vectors, they are the representative coordinates of the rows and columns, respectively, of such a grid. If they are two-element vectors, they are treated as latitude and longitude limits, and a graticule mesh of size(map) is calculated. h = surfm(lat,lon,map,alt) sets the z-axis altitude of the graticule mesh. alt must be the same size as lat. If no alt is supplied, the mesh is plotted at z=0, unless lat is the same size as map, in which case zdata=map, and a 3-D topological map results. Since the default graticule is the size of map, the default condition for surfm is to create the topographic map. h = surfm(lat,lon,map,PropertyName,PropertyValue,…) allows the input of property/value pairs to control the surface object properties. Any property supported by the standard MATLAB command surface except XData, YData, and ZData can be altered in this manner. See Also meshgrat Construct map graticule grid meshm Regular matrix map warped to projected graticule mesh pcolorm Projected matrix map in the z = 0 plane surfacem Matrix map warped to projected graticule mesh Source.