Contrast and colorimetry measurements versus viewing angle for microdisplays

Moreau, O.; Curt, Jean-Noel; Leroux, Thierry

doi:10.1117/12.411767

Cited by 2 publications

(1 citation statement)

References 24 publications

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“…Illustration of the principles of Fourier's optics device used in the experiment. Adapted from (Moreau et al, 2000) and Eldim's SA technical manuals (www.eldim.fr). Each colored ray corresponds to a specific reflection direction.…”

Section: Representativeness Of Measurementsmentioning

confidence: 99%

Wheat leaf bidirectional reflectance measurements: Description and quantification of the volume, specular and hot-spot scattering features

Comar

Baret²,

Viénot

et al. 2012

Remote Sensing of Environment

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This study focuses on the directionality of wheat leaf reflectance as a function of leaf surface characteristics. Wheat leaf BRF measurements were completed under 45°zenith illumination angle in three visible broad spectral bands with a conoscope that provides very high angular resolution data over a large portion of the whole hemisphere, including around the illumination direction. The measurements show a clear anisotropy with a specular lobe in the forward scattering direction and a small but significant hotspot feature in the backward scattering direction. The BRF directional features further depend on the illumination orientation because of the leaf roughness created by longitudinal veins: the specular lobe was more pronounced when the illumination was perpendicular to the veins, while specular reflection was more spread over azimuths for longitudinal illumination. Moreover, a sharp hotspot feature was observed for transversal illumination where the apparent roughness is the largest. The scattering was tentatively decomposed into specular, hotspot and isotropic components. Results showed that the hotspot contribution to the directional hemispherical reflectance factor (DHRF) was marginal conversely to that of the specular component that ranges between 0.036 and 0.050 (absolute DHRF value). The specular component was almost the same in the three visible bands considered. The isotropic component originating from volume scattering was contributing the most to the DHRF and was depending on wavelength, ranging between 0.055 and 0.097 in absolute DHRF value. A simple model was proposed to estimate the volume scattering from the isotropic and the surface components. Consequences of these findings were drawn on the ability to estimate leaf biochemical composition independently from leaf surface scattering, as well as on the interpretation of remote sensing at the canopy level.

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Section: Representativeness Of Measurementsmentioning

confidence: 99%

Wheat leaf bidirectional reflectance measurements: Description and quantification of the volume, specular and hot-spot scattering features

Comar

Baret²,

Viénot

et al. 2012

Remote Sensing of Environment

View full text Add to dashboard Cite

show abstract

Recognizing real materials from their glossy appearance

et al. 2010

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In everyday life, the visual system is remarkably good at recognizing materials across a wide range of viewing conditions. This paper addresses the problem of identifying real samples of materials from appearance. Here, we consider gloss as an appearance attribute that could reveal certain information about object properties. We prepared twelve samples of glass and PMMA and eroded these using different agents. The gloss and haze of the samples were measured at 60 degrees via a gloss meter. For all samples, the surface roughness properties were measured. Microfacet distributions were derived from measured BRDFs using an inverted microfacet model. We conducted a visual ranking experiment using the pair comparison method. The psychophysical gloss ratings correlate well with the 60 degrees gloss index. Principal component analysis of the psychophysical results revealed a somewhat more complicated picture in which three components seem to play a role. We conclude that observers can apprehend the physical nature of the surface of real objects from features that are included in the BRDF and available in the gloss appearance.

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Contrast and colorimetry measurements versus viewing angle for microdisplays

Cited by 2 publications

References 24 publications

Wheat leaf bidirectional reflectance measurements: Description and quantification of the volume, specular and hot-spot scattering features

Wheat leaf bidirectional reflectance measurements: Description and quantification of the volume, specular and hot-spot scattering features

Recognizing real materials from their glossy appearance

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