Multi-modal Alignment and Attention Based Person Search via Natural Language Description

Visual Internet of Things (VIoT) has been widely deployed in the field of social security. However, how to enable it to be intelligent is an urgent yet challenging task. In this article, we address the task of searching persons with natural language description query in a public safety surveillance system, which is a practical and demanding technique in VIoT. It is a fine-grained many-to-many cross-modal problem and more challenging than those with the image and the attribute as queries. The existing attempts are still weak in bridging the semantic gap between visual modality from different camera sensors and text modality from natural language descriptions. We propose a deep person search approach with a natural language description query by employing the attention mechanism (AM) and multimodal alignment (MA) method to supervise the cross-modal mapping. Particularly, the AM consists of two self-attention modules and one cross-attention module, where the former aims at learning discriminative representations and the latter supervises each other with their own information to offer accurate guidance to a common space. The MA approach contains three alignment processes with a novel cross-ranking loss function to make different matching pairs separable in a common space. Extensive experiments on large-scale CUHK-PEDES demonstrate the superiority of the proposed approach.