An illustrative image descriptor generation system generates a descriptor listing that includes a plurality of image descriptors corresponding to different feature points included within an image. Based on the descriptor listing, the system generates a geometric map representing the plurality of image descriptors in accordance with respective geometric positions of the corresponding feature points of the image descriptors within the image. Based on the geometric map, the system determines a proximity listing for a primary image descriptor within the plurality of image descriptors. The proximity listing indicates a subset of image descriptors that are geometrically proximate to the primary image descriptor within the image. Based on the proximity listing, the system selects a secondary image descriptor from the subset of image descriptors and combines the primary and secondary image descriptors to form a composite image descriptor. Corresponding methods and systems are also disclosed.