RAID: A Relation-Augmented Image Descriptor.

As humans, we regularly interpret scenes based on how objects are related, rather than based on the objects themselves. For example, we see a person riding an object X or a plank bridging two objects. Current methods provide limited support to search for content based on such relations. We present raid, a relation-augmented image descriptor that supports queries based on inter-region relations. The key idea of our descriptor is to encode region-to-region relations as the spatial distribution of point-to-region relationships between two image regions. raid allows sketch-based retrieval and requires minimal training data, thus making it suited even for querying uncommon relations. We evaluate the proposed descriptor by querying into large image databases and successfully extract non-trivial images demonstrating complex inter-region relations, which are easily missed or erroneously classified by existing methods. We assess the robustness of raid on multiple datasets even when the region segmentation is computed automatically or very noisy.