1. A method to locate a robot using an omni-directional image, the method comprising: acquiring the omni-directional image from a robot; extracting a predetermined current line from the acquired omni-directional image; calculating a correlation coefficient between the extracted current line of the robot and each pre-stored landmark line of nodes corresponding to locations in a robot-locatable area using a Fast Fourier Transform (FFT); selecting M nodes at which the calculated correlation coefficient is equal to or higher than a predetermined value; modifying a current line of the robot such that same spatial objects are located at a same location on a basis of the landmark lines of the selected M nodes to create a wrapped current line; calculating a correlation coefficient between the wrapped current line of the robot and the landmark lines of the M nodes; selecting N nodes at which the calculated correlation coefficient is equal to or higher than a predetermined correlation coefficient such that N<M; and recognizing a location of the robot on a basis of the selected N nodes, wherein the pre-stored landmark lines of the nodes are lines pre-extracted from omni-directional images acquired when the robot is located at the nodes in the robot-locatable area.