Characterizing the Gradient of the Spectral Curve for Object-Based
Random Forest Image Classification Using Airborne Hyperspectral Datasets
Abstract
There have always been some challenges within the remote sensing
community related to the processing of contiguous spectral bands
contained in hyperspectral datasets. Most approaches would resort to
using averaged spectral information over wide bandwidths resulting in
loss of crucial information available in those contiguous bands. The
loss of information could mean a drop in the discriminative power when
it comes to land cover classes with comparable spectral responses, as in
the case of cultivated fields versus fallow lands. In this study, we
proposed and tested three optimized novel algorithms based on Moment
Distance Index (MDI) that characterizes the whole shape of the spectral
curve. The image classification tests conducted on two publicly
available hyperspectral data sets (AVIRIS 1992 Indian Pine and HYDICE
Washington DC Mall images) showed the robustness of the optimized MDI
algorithms in terms of classification accuracy. We achieved an overall
accuracy of 98% and 99% for AVIRIS and HYDICE, respectively using the
optimized MDI algorithms. The optimized indices were also time efficient
as it avoided the process of band dimension reduction, such as those
implemented by several well-known classifiers. Our results showed the
potential of the optimized shape indices to discriminate between
grass/pasture and grass/trees, tree and grass, and between types of
tillage (corn-min and corn-notill) under object-based random forest
approach. The results highlight the importance of MDI that completely
utilizes the contiguous spectral bands to define the gradient of the
curve and improve image classification accuracy.