 load mri; D = squeeze(D);                                                   
 [x y z D] = subvolume(D, [nan nan nan nan nan 4]);                          
 p = patch(isosurface(x,y,z,D, 5), 'FaceColor', 'red', 'EdgeColor', 'none'); 
 p2 = patch(isocaps(x,y,z,D, 5), 'FaceColor', 'interp', 'EdgeColor', 'none');
 isonormals(x,y,z,D,p);                                                      
 view(3); axis tight;  daspect([1 1 .4])                                     
 colormap(gray(100))                                                         
 camva(6); box on                                                            
 camlight(40, 40); camlight(-20,-10); lighting gouraud 