Hi Anis, what method are you using for creating the surfaces?

Was that done by creating completely separate surfaces for each quadrant?

Creating surfaces separately like that will rarely give you a nice smooth result between the individual pieces, you need to create the surfaces in larger sheets to make them smooth.

Please see this previous post for an example:
http://moi3d.com/forum/index.php?webtag=MOI&msg=1398.19


If you have something that is close to the shape you want though, you could try trimming back some space between the pieces and putting in surface blends to connect them up.

But the best way to get a nice shape at the pole is to use Revolve or rail revolve.

- Michael