It depends whether your data is gridded or scattered. Follow the below code to get what you want. Let A be your m*2 array.
x = A(:,1) ; y = A(:,2) ;
%%structured
xi = unique(x) ; yi = unique(y) ;
[X,Y] = meshgrid(xi,yi) ;
figure
plot(X,Y,'.r')
%%unstructured
dt = delaunayTriangulation(x,y) ;
tri = dt.ConnectivityList ;
figure
trimesh(tri,x,y)
