Multispectral Change Detection With Bilinear Convolutional Neural Networks

Recently, deep learning has been demonstrated to be an effective tool to detect changes in bitemporal remote sensing images. However, most existing methods based on deep learning obtain the ultimate change map by analyzing the difference image (DI) or the stacked feature vectors of input images, which cannot sufficiently capture the relationship between the two input images to obtain the change information. In this letter, a new method named bilinear convolutional neural networks (BCNNs) is proposed to detect changes in bitemporal multispectral images. The model can be trained end to end with two symmetric convolutional neural networks (CNNs), which are capable of learning the feature representation from bitemporal images and utilizing the relations between the two input images by a linear outer product operation in an effective way. Specifically, two sets of patches obtained from two multispectral images of different times are first input into two CNNs to extract deep features, respectively. Then, the matrix outer product is applied on the output feature maps to obtain the combined bilinear features. Finally, the ultimate change detected result can be produced by applying the softmax classifier on the combined features. Experimental results on real multispectral data sets demonstrate the superiority of the proposed method over several well-known change-detection approaches.