怎么用matlab画地球曲线

cla reset;
load topo;
[x y z] = sphere(45);
s = surface(x,y,z,'facecolor','texturemap','cdata',topo);
set(s,'edgecolor','none','facealpha','texture','alphadata',topo);
set(s,'backfacelighting','unlit');
colormap(topomap1);
alpha('direct');
alphamap([.1;1])
axis off vis3d;
campos([2 13 10]);
camlight;
lighting gouraud;