Under the Lambertian reflectance model, uncalibrated photometric stereo with unknown light sources is inherently ambiguous. In this paper, we consider the use of a more general reflectance model, namely the Torrance and Sparrow model, in uncalibrated photometric stereo. We demonstrate that this can not only resolve the ambiguity when the light sources are unknown, but can also result in more ac...

Article history: Received 2 August 2016 Accepted 18 October 2016 Available online 21 October 2016 Editor: N. Lambert

Article history: Received 24 November 2016 Received in revised form 17 February 2017 Accepted 19 February 2017 Available online 28 February 2017 Editor: N. Lambert

The commonly made assumption of Lambertian behaviour of fluorescence emission has been studied in solid amorphous material. A goniofluorometer capable of measurements in measurement geometries from 0 : 10 to 0 : 85 has been used for this purpose. The measurements indicate that the fluorescence emission from solid amorphous material is clearly non-Lambertian.

The bidirectional reflectance characteristics of vegetation canopies vary with time of day and through the growing season. In this study the effects of sun and view angles on bidirectional reflectance factors from corn (Zea mays L.) canopies ranging in development from the six leaf stage to harvest maturity were examined. For nadir-acquired reflectance factors there was a strong solar angle dep...

Reflectance values for image-based relighting are often estimated from grouped pixels with similar reflectance, but such groupings are difficult to compute with certainty for sparse image data. To address this problem, we propose an iterative method that aggregates BRDF data in a single image with known geometry and lighting by soft grouping, where pixels contribute to one another’s estimate ac...

PURPOSE To characterize the normal values of acoustic energy reflectance obtained with pure-tone stimulation in neonates prior to hospital discharge. METHODS Seventy-seven infants (37 girls and 40 boys) were evaluated by measuring acoustic reflectance using pure-tone stimuli, transient-evoked otoacoustic emissions, and tympanometric probe frequencies of 226 Hz and 1 kHz. RESULTS At low freq...

In the present study, discrete trial familiarization/novelty techniques were used to study lightness constancy in 4-month-old infants. The test stimuli were real objects (paper smiley faces) of two different reflectances, dark gray (17% reflectance) and light gray (54% reflectance). In Experiment 1, the test stimuli were viewed against a white (90% reflectance) surround, and in Experiment 2, ag...

In this paper we present a method that, given the tristimulus values under a known illuminant, make it possible to compute a reflectance function that is in the range between 0 and 1 of physically admissible values without altering the corresponding tristimulus values. We represent the unknown reflectance function with a three-dimensional linear model. 1. INTRODUCTION A common problem in spectr...

The reflectance factors of transparent fibers, free delustering agent, are predicted by geometric as well as Kubelka-Munk models. Transparent fibers are simulated by a net of glass capillary tubes containing different solutions of dyestuffs. Based on the results, prediction of the reflectance factor of capillary net by geometric model is relatively better than those obtained from Kubelka-Munk...