CIDA Spring 2021 Seminar (reschedule)- Bill Philpot: Two-dimensional Normalized Difference metrics: Distinguishing soil and partial vegetation cover
From Gabriela Cestero
Cornell Institute for Digital Agriculture - Fall 2021 Seminar: Digital Agriculture for Sustainable Farming
Two-dimensional Normalized Difference metrics: Distinguishing soil and partial vegetation cover
Bill Philpot, Professor, Civil & Environmental Engineering, College of Engineering
Identification of materials based on spectral reflectance is confounded by variations in reflectance magnitude that are independent of the spectral shape. In particular, this complicates the quantification of partial vegetation cover. Local variations such as the viewing/illumination angles, multiscale soil surface roughness, soil moisture content, even differences in leaf angle can all drive changes in magnitude that are distinct from the spectral variations of interest, and complicate detection, identification and modeling of targets based on spectral features. Normalization metrics that remove magnitude variations can greatly clarify the nature of spectral differences, allowing for more effective interpretation of reflectance features in spectral imagery. The 2-dimensional normalized difference space, described in this presentation, allows for improved discrimination among bare soils and emergent vegetation when there are multiple soil types in the scene. Normalized difference indices are used because of the simplicity of the computation, the convenient scaling, and the ease with which the normalized difference procedure can be extended to multiple dimensions.
Bill Philpot is a Professor in Civil & Environmental Engineering at Cornell University with a focus on spectral remote sensing. His research emphasizes understanding the interaction of light with materials on the earth's surface and deriving tools for extracting useful spectral information from the reflected light.