Fig. 10

Normalized reflectance spectral responses with correlation values when illuminating the polymer reference with lamps B and D from Fig. 3 and captured with different sensors. Spectrometer measurements were performed with a fibre optic orthogonal to the polymer reference from a 5 cm distance. The hyperspectral camera captures a scene of the polymer at approximately 72.5 degrees and 40.5 cm distance and uses a region of interest of 25 × 25 pixels. Note that captures taken at 90^∘ and 0^∘ would mean pointing the camera to a vertical wall and to the floor, respectively. These responses from the HS cameras are the mean spectral signatures of the 25 × 25 pixel polymer pixels with their corresponding standard deviations, shown with shaded colours between their corresponding means. The spectrometer uses 2055 bands and covers the 350–925 nm range. The HS linescan VNIR camera covers the 400–1000 nm spectral range and uses 369 bands. Finally, the HS snapshot NIR camera spectra ranges from 660–950 nm and includes 25 bands. The Pearson correlation is presented after the measured bands of each sensor are compared with the polymer reference response. The visible (VIS) spectra is illustrated with rainbow shading in the 380–740 nm range.