1. A method for identifying and positioning a building using a mountain-based outline region restraint, comprising the steps of: (1) obtaining a real-time image, detecting a mountain-based outline of said real-time image, and extending said mountain-based outline, wherein obtaining a mountain-based outline restraint region; (2) conducting morphological enhancement and background suppression on said image in said mountain-based outline restraint region; (3) conducting recursive segmentation in said mountain-based outline restraint region, wherein transforming an image obtained in step (2) into a binary image; (4) extracting local regions of interest of a target building in said mountain-based outline restraint region according to said binary image; and (5) directly identifying and positioning said target building in said local regions of interest.