Superresolution Land Cover Mapping With Multiscale Information by Fusing Local Smoothness Prior and Downscaled Coarse Fractions

Superresolution mapping (SRM) is a technique for translating original coarse-resolution fractions into a fine-resolution land cover map by dividing a coarse-resolution pixel into a few finer resolution pixels and determining their class labels. SRM can be solved by considering it a maximum a posteriori principle-based classification problem and by assigning each fine pixel as the class with the highest probability. Fine-pixel class membership probabilities (CMPs) can be calculated at two different scales: at the fine scale, in which the target fine pixel is compared with other fine pixels, and at the coarse scale, in which coarse fractions are downscaled into fine-pixel probabilities. The fine-scale CMP is suitable for representing local land cover features but not for maintaining global features. The coarse-scale CMP is the opposite of the fine-scale CMP. This paper proposes a novel multiscale approach to overcome this shortcoming by fusing the CMP calculated at both fine and coarse scales with the tau model. With the fused CMP, a simulated-annealing algorithm is applied to produce a fine-resolution land cover map. The land cover maps generated from QuickBird and IKONOS images and the National Land Cover Database were used to validate the effectiveness of the proposed SRM algorithms. The proposed SRM algorithms were evaluated visually and quantitatively by comparing them with several existing SRM algorithms. The results indicate that the accuracy of land cover maps at fine spatial resolution increased significantly compared with that obtained from all existing SRM algorithms.