[Invited Paper] Spatial Verification via Pairwise Geometric Constraints and 3D View-Directional Voting

Abstract

Existing instance search methods based on spatial verification still suffer from limited efficiency and large 3D viewpoint changes. To address these issues, we newly incorporate two spatial verification methods in local feature-based instance search. The first method, called ensemble of weak geometric relations, imposes multiple pairwise geometric constraints on pairs of feature correspondences. It leverages the coherence of the spatial neighborhood to reduce its complexity from quadratic time to linear time in terms of the number of correspondences. The second method, which is called angle-free object information retrieval, converts each image into a set of affine-transformed images to augment the information used for search and to neutralize the viewpoint changes between two images. Extensive experiments conducted on two TRECVID instance search datasets show the superiority of our methods, which provide high robustness as regards large 3D viewpoint changes, small instances and occlusions.