A system to navigate a procedure relative to a subject, comprising: a display device to display a first image having a first segmented portion and a second segmented portion, wherein the first segmented portion in the first image corresponds to a first vertebra of the subject and the second segmented portion in the first image corresponds to a second vertebra of the subject; a first tracking system defining a first tracking space with a first coordinate system; a second tracking system defining a second tracking space with a second coordinate system; a reference point tracking system having (i) a first tracking device trackable in the first coordinate system and (ii) a second tracking device trackable in the second coordinate system; a third tracking device trackable in the second coordinate system, wherein the third tracking device is associated with the first segmented portion in a data of the first image; a fourth tracking device trackable in the second coordinate system, wherein the fourth tracking device is associated with the second segmented portion in the data of the first image; and a navigation processor system operable to: register a first image data coordinate system of the data of the first image to the first tracking space based on the reference point tracking system; correlate the first coordinate system and the second coordinate system due at least to the reference point tracking system; and identify a first end plate (170, 616) of the first vertebra and a second end plate (174, 618) of the second vertebra in the first image, identify lines (610, 612) or planes (178, 182) of the identified respective first end plate and second end plate (170, 174), update the first image, including changing a position of the first segmented portion or the second segmented portion (166i") and determining and illustrating an angle (210, 630) between the identified lines (610, 612) or the identified planes (178, 182) after the change of position, based upon tracking the third tracking device and tracking the fourth tracking device, wherein the updated image is based on the correlation of the first coordinate system and the second coordinate system, and generate the updated first image for display with the display device. a display device to display a first image having a first segmented portion and a second segmented portion, wherein the first segmented portion in the first image corresponds to a first vertebra of the subject and the second segmented portion in the first image corresponds to a second vertebra of the subject; a first tracking system defining a first tracking space with a first coordinate system; a second tracking system defining a second tracking space with a second coordinate system; a reference point tracking system having (i) a first tracking device trackable in the first coordinate system and (ii) a second tracking device trackable in the second coordinate system; a third tracking device trackable in the second coordinate system, wherein the third tracking device is associated with the first segmented portion in a data of the first image; a fourth tracking device trackable in the second coordinate system, wherein the fourth tracking device is associated with the second segmented portion in the data of the first image; and a navigation processor system operable to: register a first image data coordinate system of the data of the first image to the first tracking space based on the reference point tracking system; correlate the first coordinate system and the second coordinate system due at least to the reference point tracking system; and identify a first end plate (170, 616) of the first vertebra and a second end plate (174, 618) of the second vertebra in the first image, identify lines (610, 612) or planes (178, 182) of the identified respective first end plate and second end plate (170, 174), update the first image, including changing a position of the first segmented portion or the second segmented portion (166i") and determining and illustrating an angle (210, 630) between the identified lines (610, 612) or the identified planes (178, 182) after the change of position, based upon tracking the third tracking device and tracking the fourth tracking device, wherein the updated image is based on the correlation of the first coordinate system and the second coordinate system, and generate the updated first image for display with the display device. register a first image data coordinate system of the data of the first image to the first tracking space based on the reference point tracking system; correlate the first coordinate system and the second coordinate system due at least to the reference point tracking system; and identify a first end plate (170, 616) of the first vertebra and a second end plate (174, 618) of the second vertebra in the first image, identify lines (610, 612) or planes (178, 182) of the identified respective first end plate and second end plate (170, 174), update the first image, including changing a position of the first segmented portion or the second segmented portion (166i") and determining and illustrating an angle (210, 630) between the identified lines (610, 612) or the identified planes (178, 182) after the change of position, based upon tracking the third tracking device and tracking the fourth tracking device, wherein the updated image is based on the correlation of the first coordinate system and the second coordinate system, and generate the updated first image for display with the display device.