A method of aligning a component within a turbine casing, the turbine casing including an upper casing and a lower casing configured to collectively surround a rotor, the rotor having a rotor axis, the method comprising: for at least one primary axial location along the rotor axis and at one or both sides of the turbine casing at each primary axial location: with the upper casing coupled to the lower casing in a top-on position, measuring: a first location of a first reference point at a first optical target coupled to an outer surface of a horizontal joint flange of the lower casing, and a second location of a second reference point at a second optical target coupled to the outer surface of the HJ flange of the lower casing and vertically spaced from the first optical target; with at least the upper casing removed from the lower casing in a top-off position, measuring: a third location of the first reference point at the first optical target, a fourth location of the second reference point at the second optical target, a fifth location of a third reference point on an upper surface of the horizontal joint flange of the lower casing, the third reference point having a known spatial relation to a component support position of the component in the lower casing at the respective primary axial location, and a sixth location of a fourth reference point on the upper surface of the HJ flange of the lower casing, the fourth reference point spaced from the third reference point on the upper surface of the HJ flange of the lower casing; calculating a prediction offset value for the component support position in the top-on position based on at least the first, second, third, fourth, fifth and sixth locations (L1-L6) and an inner radius of the lower casing; and adjusting the component support position in the turbine casing by the prediction offset value, wherein an alignment of the component positioned at the component support position is improved relative to the rotor axis upon replacing the upper casing to the top-on position. a first location of a first reference point at a first optical target coupled to an outer surface of a horizontal joint flange of the lower casing, and a second location of a second reference point at a second optical target coupled to the outer surface of the HJ flange of the lower casing and vertically spaced from the first optical target; with at least the upper casing removed from the lower casing in a top-off position, measuring: a third location of the first reference point at the first optical target, a fourth location of the second reference point at the second optical target, a fifth location of a third reference point on an upper surface of the horizontal joint flange of the lower casing, the third reference point having a known spatial relation to a component support position of the component in the lower casing at the respective primary axial location, and a sixth location of a fourth reference point on the upper surface of the HJ flange of the lower casing, the fourth reference point spaced from the third reference point on the upper surface of the HJ flange of the lower casing; calculating a prediction offset value for the component support position in the top-on position based on at least the first, second, third, fourth, fifth and sixth locations (L1-L6) and an inner radius of the lower casing; and adjusting the component support position in the turbine casing by the prediction offset value, wherein an alignment of the component positioned at the component support position is improved relative to the rotor axis upon replacing the upper casing to the top-on position. a third location of the first reference point at the first optical target, a fourth location of the second reference point at the second optical target, a fifth location of a third reference point on an upper surface of the horizontal joint flange of the lower casing, the third reference point having a known spatial relation to a component support position of the component in the lower casing at the respective primary axial location, and a sixth location of a fourth reference point on the upper surface of the HJ flange of the lower casing, the fourth reference point spaced from the third reference point on the upper surface of the HJ flange of the lower casing; calculating a prediction offset value for the component support position in the top-on position based on at least the first, second, third, fourth, fifth and sixth locations (L1-L6) and an inner radius of the lower casing; and adjusting the component support position in the turbine casing by the prediction offset value, wherein an alignment of the component positioned at the component support position is improved relative to the rotor axis upon replacing the upper casing to the top-on position.