Processed NIR-HSI and self-organizing map dataset for microplastic classification on sandy substrates

Processed supporting dataset for the manuscript 'Hyperspectral imaging and self-organizing map approach for non-destructive monitoring of microplastic contamination in sandy substrates.' The collection contains processed reference spectra for PET, PE, PP, PS, and sand; trained self-organizing map inputs and outputs; percent-based expansion tolerance colormaps; and representative projection and classification structures used for polymer mapping and surface-coverage estimation. It is not a complete archive of all raw hyperspectral cubes or every intermediate variable.