Building Detection from Satellite Imagery using Ensemble of Size-specific Detectors

In recent years, convolutional neural networks (CNNs) show remarkably high performance in building detection tasks. While much progress has been made, there are two aspects that have not been considered well in the past: how to address a wide variation in building size, and how to well incorporate with context information such as roads. To answer these questions, we propose a simple, but effective multi-task model. The model learns multiple detectors each of which is dedicated to a specific size of buildings. Moreover, the model implicitly utilizes context information by simultaneously training road extraction task along with building detection task. The road extractor is trained by distilling knowledge from another pre-trained CNN, requiring no labels for roads in its training. Our experiments show that the proposed model significantly improves the building detection accuracy.