Publicaties
Snapshot and linescan hyperspectral imaging for visual appearance measurements KU Leuven
Hyperspectral imaging techniques offer interesting new methods of measuring visual appearance. In this paper, two different types of hyperspectral cameras (snapshot vs. linescan) are compared on a theoretical and practical basis, and it is tested if they could be used for visual appearance measurements. The cameras are first characterized and calibrated. A GretagMacbeth ColorChecker® is then used to compare and evaluate the quality of the ...
Soft metrology of transmission haze: an exploratory study KU Leuven
This study assesses optical measurement methods for the characterization of transmission haze in correlation with its visual perception. For this, seven silica-filled amorphous polymer test samples were selected from a developed sample set. Commercial haze meters and alternative measuring techniques were used to quantify the haze of the test sample set optically. Visual scales were derived using the maximum likelihood difference scaling ...
The UGR correction factor: a case study KU Leuven
The Unified Glare Rating (UGR) quantifies the level of discomfort glare of indoor light sources and luminaires. UGR values are calculated based on both the luminous intensity distribution and physical dimensions of the light emitting surface of a light source. While a luminous intensity distribution is strictly defined, a light emitting surface is not and can be quite ambiguous to determine, especially with modern LED based luminaires. In this ...
Effect of surface curvature on specular gloss evaluations KU Leuven
Conventional gloss meters are generally used to measure specular gloss, also for curved surfaces despite their suitability for flat artefacts only. In this study, three curved sample sets of a different gloss level (glossy, satin and matt) were developed, consisting a total of 27 samples. Of each sample the specular gloss was determined with three different devices: a commercial handheld apparatus, a reduced beam-size instrument and an ...
Road marking BRDF model applicable for a wide range of incident illumination conditions KU Leuven
To drive safely and comfortably, an adequate contrast between the road surface and road markings is needed. This contrast can be improved by using optimized road illumination designs and luminaires with dedicated luminous intensity distributions, taking advantage of the (retro)reflective characteristics of the road surface and road markings. Since little is known about road markings' (retro)reflective characteristics for the incident and viewing ...
Optical characterization of the psychophysical surface gloss space in the presence of surface haze KU Leuven
An unanimous framework for surface gloss perception does not exist yet, although an orthogonal two-dimensional gloss space (distinctness-of-image and contrast gloss) has already been proposed. Haze, a rarely studied attribute of glossiness, is considered in this study and introduced into this existing space. A set of samples with surface haziness is psychophysically and optically characterized. The perceived glossiness correlates with the visual ...