1. An information processing method applied to an information processing device in which a 3D map and a spatial topological structure management-based feature library created in advance for a certain environment is contained, and different users in the certain environment are able to determine their location in accordance with images taken by themselves and the feature library, the method comprising: acquiring a first image taken by a first user; extracting one or more first feature points in the first image to obtain first feature descriptors for characterizing the first feature points; obtaining 3D locations of the first feature points based on a 3D location of the first user, the first image, and the feature library; determining feature descriptors to be updated based on the 3D location of the first user, the 3D locations of the first feature points, the first feature descriptors corresponding to the first feature points, and existing feature descriptors in the feature library; and updating the feature library based on the feature descriptors to be updated, wherein the step of determining feature descriptors to be updated comprises: selecting one of the first feature points in the first image; determining a minimum spatial node crossed by a line between the selected first feature point and the location of the first user; judging whether any feature descriptors of the feature library are contained within the minimum spatial node; and determining all of the feature descriptors contained within the minimum spatial node as feature descriptors to be deleted if the judgement is positive, wherein the minimum spatial node is a space resolution in the certain space environment, and the certain space environment is divided by the minimum spatial node, wherein the step of determining feature descriptors to be updated further comprises: determining respective first feature descriptors in the first image as feature descriptors to be added; acquiring a plurality of strength information of the feature descriptors to be added; and among the feature descriptors to be added, removing feature descriptors of which the plurality of strength information are less than a first threshold; and wherein the step of determining feature descriptors to be updated further comprises: determining respective first feature descriptors in the first image as feature descriptors to be added; calculating a similarity degree between the feature descriptors to be added and the feature descriptors in the feature library at the corresponding minimum spatial node, wherein they are considered to be similar if the similarity degree greater than a second threshold; and among the feature descriptors to be added, removing feature descriptors which are considered similar to the feature descriptors in the feature library.