Exploring the Capacity of Sequential-free Box Discretization Network for Omnidirectional Scene Text Detection

Omnidirectional scene text detection has received increasing research attention. Previous methods directly predict words or text lines of quadrilateral shapes. However, most methods neglect the significance of consistent labeling, which is important to maintain a stable training process, especially when a large amount of data are included. For the first time, we solve the problem in this paper by proposing a novel method termed Sequential-free Box Discretization (SBD). The proposed SBD first discretizes the quadrilateral box into several key edges, which contains all potential horizontal and vertical positions. In order to decode accurate vertex positions, a simple yet effective matching procedure is proposed to reconstruct the quadrilateral bounding boxes. It departs from the learning ambiguity which has a significant influence during the learning process. Exhaustive ablation studies have been conducted to quantitatively validate the effectiveness of our proposed method. More importantly, built upon SBD, we provide a detailed analysis of the impact of a collection of refinements, in the hope to inspire others to build state-of-the-art networks. Combining both SBD and these useful refinements, we achieve state-of-the-art performance on various benchmarks, including ICDAR 2015, and MLT. Our method also wins the first place in text detection task of the recent ICDAR2019 Robust Reading Challenge on Reading Chinese Text on Signboard, further demonstrating its powerful generalization ability. Code is available at https://tinyurl.com/sbdnet.