1. A system for performing and visualizing a measurement of an object viewed in an image computed from image data, the system comprising: an image unit for visualizing the image data in the image for displaying in a display; a deployment unit for deploying a caliper in an image data space based on the location of the object in the image data space; a caliper unit for visualizing the caliper in the image; and a manipulation unit for manipulating the caliper in the image data space, wherein the manipulating is in response to a user input, and wherein the manipulating comprises at least one of scaling, translating, and rotating the caliper in the image; and further wherein the scaling may be isotropic, anisotropic, or directional; wherein the caliper comprises a first planar surface and a second planar surface substantially parallel to the first planar surface, wherein the deployment unit further comprises the first and second planar surfaces which are rotatable in three-dimensional space about a selected axis, wherein the measurement of the object is determined based on the distance between the planes of the first and second planar surface, and wherein the caliper unit visualizes the caliper by computing an image of the caliper using data from at least the deployment unit or the manipulation unit.