Super-Resolution Mapping With a Fraction Error Eliminating CNN Model

Super-resolution mapping (SRM) is an effective way to alleviate the mixed pixel problem of remotely sensed imagery by transforming the coarse-resolution fraction image originating from spectral unmixing into a fine-resolution land cover map. Deep learning has been widely used in SRM since it has a powerful ability to represent the complex heterogeneous spatial distribution patterns of land cover patches; however, the accuracy of existing deep learning-based SRM models is compromised by the fact that the fraction images used in SRM always contain errors. In this article, we propose an end-to-end convolutional neural network (CNN)-based fraction error eliminating SRM (DeepNESRM) method to overcome the negative effect of fraction errors in SRM. In DeepNESRM, to better learn the complex nonlinear relationship between the actual coarse-resolution fraction image and the fine-resolution land cover map by the CNN, a practical error simulation method that considers the characteristics of fraction errors is introduced to produce training samples. In addition, a multilevel feature fusion CNN is adopted to eliminate fraction errors and simultaneously implement SRM. Experiments using Sentinel-2 and Landsat 8 images were conducted to test the performance of the proposed method. Two conventional SRM methods, namely the pixel swapping method and the spatial dependence and L2 norm combined SRM (L2_SRM) method, and also a stacked very deep CNN-based SRM (VDSRM) method, were used as the comparison methods. The results show that DeepNESRM can deal with fraction errors, preserve the spatial detail information, and achieve higher average overall accuracies than the other methods.