Mirror?

When I apply the mirror modifier the object that is mirroring the other object is very far away from the original. This has me very confused.:confused:

The center of the mirroring is the origin/model center.

You need to have this origin/model center to be placed correctly.
By example i have this half sphere that i moved :
http://i.imgur.com/0y5uk.jpg

Notice the “brown/orange” point , it’s the origin/model center, in this situation if i use a mirror now, i will not be able to get the half sphere becoming a sphere because the origin that is the center of the mirroring symetry is far from my half sphere .

http://i.imgur.com/WjO56.jpg

to fix that, in Edit Mode, i need to select those vertices that are located where i would want the axe of symetry to be :
http://i.imgur.com/S4Nlf.jpg

Theni click on Mesh -> Snap -> Cursor to Selected.
http://i.imgur.com/GklSm.jpg
That will move the 3D cursor where i need

Then, in Object Mode, click on the “Origin” button in the Object Tool panel to the right of your screen
http://i.imgur.com/VZlRI.jpg
and select “Origin to 3D Cursor”
It will move the Origin to the 3D cursor location, it will then be where i really need for the mirror to work the correct symetry i need
http://i.imgur.com/3dHhH.jpg

Using the mirror modifier will now give me the correct mirrored half sphere i need to complete the sphere.

Okay thank you.