1. An apparatus for calculating spatial coordinates of a user's eyes, comprising: a feature point extractor configured to extract feature points from a single input image of an object; an image generator that is a single camera module configured to generate the input image by photographing the object; a direction vector calculator configured to calculate, by a processor, an object direction vector based on the single input image, and a feature direction vector based on position of the feature points in the single input image; and a spatial coordinate calculator configured to calculate, by a processor, spatial coordinates of a feature point based on a pre-established reference distance, the feature direction vector, and the object direction vector, wherein the spatial coordinate calculator is further configured to output the spatial coordinates to an auto-stereoscopic display, wherein the pre-established reference distance is associated with a distance between the eyes of a reference human or a calibrated value based on a user setting, wherein the extracted feature points comprise the eyes of the user, wherein the feature direction vector is a vector between the center point of the single camera module and the respective feature point, wherein the feature direction vector is further calculated based on input camera parameters and pixel position information of the respective feature point, wherein the input camera parameters comprise a horizontal field of view of the input image, a vertical field of view of the input image, a horizontal pixel resolution of the input image, and a vertical pixel resolution of the input image, and wherein the pixel position information of the respective feature point comprises a horizontal pixel position and a vertical pixel position.