Glare

Spatial–Spectral Evidence of Glare Influence on Hyperspectral Acquisitions

“…However, since our spectral range of interest is wider (400 nm to 1000 nm), we also acquired a second set RS (2) of reference reflectance spectra. These data were acquired using an Ocean Optics spectrophotometer (HR4000), with spectral sensitivity range from 200 nm to 1000 nm and average spectral resolution of 0.24 nm.…”

“…The acquisition angle was fixed at 45°and a Y-branched QR400-7-VIS-NIR optical fibre bundle was used for the acquisition. RS (2) curves for each gray level are plotted with a dotted line. Since the measures are acquired with a different instrument and with a different light source the measures present a mismatch visible in the figures of Section 3.1.…”

“…In (a,b) the solid lines represent the mean reflectance and raw acquired values respectively. In (a) the dashed lines represent the reference RS (1) in 400 nm to 700 nm and the dotted lines represent the reference RS (2) in 700 nm to 1000 nm.…”

“…where L * is the set of wavelengths on which the spectra a and b are defined (L for data acquired by the camera, L 1 for RS 1 , L 2 for RS 2 ). This way, it was possible to produce different plots combining the acquired data with the reference spectra (RS (1) , RS (2) ), in a defined spectral range, or for each wavelength. For example, Figure 9a represents GE values for the various CC patches in the full visible range from 400 nm to 700 nm where different columns with same color refers to different measured patch areas.…”

“…Glare, also referred to as flare, is often defined as a Human Visual System (HSV) condition which causes a reduced capability to see details, due to an unsuitable distribution of luminance in the scene [1,2]. Unfortunately, the term "glare" is used to refer both to the cause and to the effect of this phenomenon, as in the definition above which is a description of the effects, not of the cause.…”