Pattern Analysis and Applications | 2021
DroneRTEF:development of a novel adaptive framework for railroad track extraction in drone images
Abstract
Railroad track health monitoring is a challenging yet important task as it affects the safety of railroad systems. Railroad track extraction presents an immediate advantage during railroad inspections in an efficient and cost-effective manner. At present, human inspectors, inspection trains, and rail-mounted vehicles equipped with cameras are prevalent image acquisition systems(IAS) in the track extraction module. However, these IAS face various challenges such as high operability cost, railroad closed for normal traffic, and inaccessibility to certain geographical locations. In such scenarios, drones act as effective IAS. Therefore, this paper presents a novel and adaptive railroad track extraction framework for drone images (DI) captured under uneven illumination, at different drone flight heights, with varying rail line orientations, and in complex railroad environments. We termed this framework as DroneRTEF. This work primarily focuses on two aspects of drone-based railroad track images: image enhancement and image analysis. With regard to the first aspect, a global image enhancement algorithm named adaptive colour space-based masking (ACSM) is developed to enhance railroad track images and identify rail lines. The rail lines and background can be highlighted and homogenized, respectively, in DI captured under various sunlight intensity using ACSM due to its illuminance independence. With regard to the second aspect, the Hough parameter space analysis-based novel Hough transform-ground sample distance(HT-GSD) method is presented in this paper. The proposed HT-GSD method emphasizes on rail line detections at varying line orientations and different flight heights. The track extraction is then performed by a coordinate transformation technique. The approach has been successfully tested and validated on various DI. The efficacy of our framework for rail line detection is identified by comparing it with other line detection model. Performances of these methods are tested using metrics such as precision, recall and accuracies of the detections. Results obtained show that our method is superior to another model. Therefore, DroneRTEF is an efficient and feasible method for railroad track extraction in DI.