Deep learning based vehicle detection in aerial imagery

Detecting vehicles in aerial images is an important task for many applications like traffic monitoring or search and rescue work. In recent years, several deep learning based frameworks have been proposed for object detection. However, these detection frameworks were developed and optimized for datasets that exhibit considerably differing characteristics compared to aerial images, e.g. size of objects to detect. In this report, we demonstrate the potential of Faster R-CNN, which is one of the state-of-the-art detection frameworks, for vehicle detection in aerial images. Therefore, we systematically investigate the impact of adapting relevant parameters. Due to the small size of vehicles in aerial images, the most improvement in performance is achieved by using features of shallower layers to localize vehicles. However, these features offer less semantic and contextual information compared to features of deeper layers. This results in more false alarms due to objects with similar shapes as vehicles. To account for that, we further propose a deconvolutional module that up-samples features of deeper layers and combines these features with features of shallower layers.