  This paper describes our approach to the DIUx xView 2018 Detection Challenge
[1]. This challenge focuses on a new satellite imagery dataset. The dataset
contains 60 object classes that are highly imbalanced. Due to the imbalanced
nature of the dataset, the training process becomes significantly more
challenging. To address this problem, we introduce a novel Reduced Focal Loss
function, which brought us 1st place in the DIUx xView 2018 Detection
Challenge.
