An Unsupervised Convolutional Feature Fusion Network for Deep Representation of Remote Sensing Images

Unsupervised learning of a convolutional neural network (CNN) is a feasible method to represent and classify remote sensing images, where labeling the observed data to prepare training samples is a highly expensive and time-consuming task. In this letter, we propose an unsupervised convolutional feature fusion network to formulate an easy-to-train but effective CNN representation of remote sensing images. The efficiency and effectiveness are derived from the following two aspects. First, the proposed method trains a deep CNN through unsupervised learning of each CNN layer in a greedy layer-wise manner, which makes the training relatively easy and efficient. Second, the feature fusion strategy in the proposed network can effectively use both the information from individual layers and the important interactions between different layers. As a result, the proposed network requires only several layers to obtain comparable or even better results than very deep networks. The experiments on unsupervised deep representations and the classification of remote sensing images demonstrate the efficiency and effectiveness of the proposed method.