Triplet-Watershed for Hyperspectral Image Classification

Abstract

Hyperspectral images (HSIs) consist of rich spatial and spectral information, which can potentially be used for several applications. However, noise, band correlations, and high dimensionality restrict the applicability of such data. This is recently addressed using creative deep learning network architectures, such as ResNet, spectral-spatial residual network (SSRN), and attention-based adaptive spectral-spatial kernel residual networks (A2S2K). However, the last layer, i.e., the classification layer, remains unchanged and is taken to be the softmax classifier. In this article, we propose to use a watershed classifier. Watershed classifier extends the watershed operator from Mathematical Morphology for classification. In its vanilla form, the watershed classifier does not have any trainable parameters. In this article, we propose a novel approach to train deep learning networks to obtain representations suitable for the watershed classifier. The watershed classifier exploits the connectivity patterns, a characteristic of HSI datasets, for better inference. We show that exploiting such characteristics allows the Triplet-Watershed to achieve state-of-art results in supervised and semi-supervised contexts. These results are validated on Indian Pines (IP), University of Pavia (UP), Kennedy Space Center (KSC), and University of Houston (UH) datasets, relying on simple convnet architecture using a quarter of parameters compared to previous state-of-the-art networks. The source code for reproducing the experiments and supplementary material (high-resolution images) is available at https://github.com/ac20/TripletWatershed_Code .