Abstract
The aim of this study was to evaluate the impact of image fusion techniques on vegetation classification accuracies in a complex wetland system. Fusion of panchromatic (PAN) and multispectral (MS) Quickbird satellite imagery was undertaken using four image fusion techniques: Brovey, hue-saturation-value (HSV), principal components (PC), and Gram–Schmidt (GS) spectral sharpening. These four fusion techniques were compared in terms of their mapping accuracy to a normal MS image using maximum-likelihood classification (MLC) and support vector machine (SVM) methods. Gram–Schmidt fusion technique yielded the highest overall accuracy and kappa value with both MLC (67.5% and 0.63, respectively) and SVM methods (73.3% and 0.68, respectively). This compared favorably with the accuracies achieved using the MS image. Overall, improvements of 4.1%, 3.6%, 5.8%, 5.4%, and 7.2% in overall accuracies were obtained in case of SVM over MLC for Brovey, HSV, GS, PC, and MS images, respectively. Visual and statistical analyses of the fused images showed that the Gram–Schmidt spectral sharpening technique preserved spectral quality much better than the principal component, Brovey, and HSV fused images. Other factors, such as the growth stage of species and the presence of extensive background water in many parts of the study area, had an impact on classification accuracies.
Highlights
Wetlands cover about 9% of the surface of the Earth and contain around 35% of global terrestrial carbon
Pan-sharpened images with enhanced spatial and spectral characteristics were produced with the aim of distinguishing saltmarsh vegetation communities and identifying brackish water marshes
The classification results indicated the usefulness of infrared bands in saltmarsh vegetation discrimination as fused images that included the infrared band consistently produced higher accuracies as compared to images containing noninfrared bands
Summary
Wetlands cover about 9% of the surface of the Earth and contain around 35% of global terrestrial carbon. Wetlands help to improve water quality by filtering pollutants, trapping sediments, and absorbing nutrients that would otherwise result in poor water quality downstream They provide habitats for wildlife as well as many valuable ecosystem services.[1] Coastal wetlands, such as saltmarsh and mangroves, are likely to have the highest rates of greenhouse gas sequestration, and the drainage of melaleuca and mangrove forest wetlands in Australia would turn them from carbon sinks into carbon sources.[2] Saltmarsh can bury an average of 1.51 tons of organic carbon per hectare per year.[2,3] This rate is several times higher than the rate of carbon sink calculated for the Amazonian forests, an important global carbon sink, and highlights the importance of protecting wetlands to mitigate the impacts of climate change. They provide an important buffer between land and reef, as they filter land runoff and improve the quality of water.[4,5]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
