The Mirror command allows you to create a duplicate of a mesh that is reflected across an invisible mirror plane. You can then position this plane manually to customize and tweak the resulting geometry. Use the following options to set what happens when you select Mesh > Mirror.
Determines whether or not faces that break the cut plane are removed from the mesh.
Specifies the type of mesh Maya generates when the Mirror command is used. Default is Copy.
Specifies the plane of symmetry on which to mirror the selected polygon object. Default is World.
Specifies the axis on which to mirror the selected polygon object, centered at the Mirror Axis Position. Default value is X.
Specifies which direction to mirror the selected polygon object in the Mirror Axis. Default is positive.
Combines the original object and the mirrored object into a single mesh. Subsequent changes that you make to the original object are not updated on the mirrored object as a result. Default is on.
Specifies how to handle joining mirrored components to the original polygon mesh. Default is Merge border vertices.
Specifies the method in which vertices are merged when Border is set to Merge border vertices. Default is Automatic.
Edges on the line of symmetry between the original and copy whose bordering faces form an angle less than or equal to the Smoothing Angle are softened. Otherwise they are left hard. Default is 30.
Flips the UV copy or selected object's UV shell, depending on the current Geometry Type, in the specified Direction. Default is off.
Specifies the direction in UV space to flip the UV shell when Flip UVs is turned on. Default is Local U.