1. An object-based 3-dimensional (3D) stereo information generation method, comprising: obtaining at least two 2-dimensional (2D) images from the same area at a first time point; extracting information of a plurality of first non-physical objects from the at least two 2D images, wherein each of the first non-physical objects is a group of pixels having a similar characteristic appearing in the images; establishing a correspondence between at least two of the first objects; verifying the correspondence, wherein the verifying step includes one or more of the following: checking the closeness of the gravity centers of the corresponding objects; checking whether the overlapping area of the corresponding objects is the largest; checking where the number of laterals of the corresponding objects is the closest; and combinations of one or more of the above; generating 3D information according to the at least two first objects with correspondence; and marking a first 3D non-physical object in the 3D information to give the first 3D non physical object an identity (ID) which does not change when a coordinate of the first 3D non-physical object changes.