5. Diffuse Illumination: The Silence of the Universal

2021 ◽  
pp. 139-169
Keyword(s):  
Diffuse Illumination

Method for site characterization of anisotropic diffuse illumination of photovoltaic systems

2012 ◽  
Author(s):  
Juan M. Russo ◽  
Deming Zhang ◽  
Shelby Vorndran ◽  
Michael Gordon ◽  
Jose Castillo ◽  
...  
Keyword(s):  
Site Characterization ◽  
Photovoltaic Systems ◽  
Diffuse Illumination

Microphotometry of Underwater Shadowing by a Moss from a Niagara Escarpment Waterfall

2010 ◽  
Vol 17 (1) ◽  
pp. 125-131
Author(s):  
Howard J. Swatland
Keyword(s):  
Point Source ◽  
Single Cells ◽  
Incident Light ◽  
Polarized Light ◽  
Specular Reflectance ◽  
Light Spectra ◽  
Niagara Escarpment ◽  
Single Leaf ◽  
Diffuse Illumination ◽  
Air Water Interface

AbstractMicroscope and fiber-optic spectrophotometry of transmittance and backscattering both showed moss leaves to be capable of casting strong shadows, with a single leaf blocking approximately 90% of incident light from a point source. In leaves with only one layer of cells, the transmittance through the cytoplasm of single cells was similar to that for whole leaves. Analysis of cell wall birefringence by polarized-light interferometry indicated that cell walls might normally scatter rather than transmit light. Spectra transmitted through, or backscattered from, the upper green layers of moss were dominated by selective absorbance from chlorophyll, but there was also evidence of wavelength-dependent scattering, as detected in the lower layers of brown, dead moss. Specular reflectance from moss leaves was detected by polarimetry and may have contributed to the relatively high macroscopic transmittance of stationary moss in water. Shadowing by moss leaves was confirmed by dynamic measurements of mosses in turbulent water without bubbles. Flicker patterns from leaves were superimposed on the underwater flicker pattern created at the air-water interface, thus flecks of light were reduced in intensity, increased in frequency, and decreased in duration. This was detected with both point source and diffuse illumination of samples.

scholarly journals Image Classification for Automated Image Cross-Correlation Applications in the Geosciences

2019 ◽  
Vol 9 (11) ◽  
pp. 2357 ◽  
Author(s):  
Niccolò Dematteis ◽  
Daniele Giordan ◽  
Paolo Allasia
Keyword(s):  
Cross Correlation ◽  
Earth Science ◽  
Operative Procedure ◽  
Support Vector ◽  
Diffuse Illumination ◽  
Monitoring Applications ◽  
Correlation Processing ◽  
Classification Of Images ◽  
Active Processes

In Earth Science, image cross-correlation (ICC) can be used to identify the evolution of active processes. However, this technology can be ineffective, because it is sometimes difficult to visualize certain phenomena, and surface roughness can cause shadows. In such instances, manual image selection is required to select images that are suitably illuminated, and in which visibility is adequate. This impedes the development of an autonomous system applied to ICC in monitoring applications. In this paper, the uncertainty introduced by the presence of shadows is quantitatively analysed, and a method suitable for ICC applications is proposed: The method automatically selects images, and is based on a supervised classification of images using the support vector machine. According to visual and illumination conditions, the images are divided into three classes: (i) No visibility, (ii) direct illumination and (iii) diffuse illumination. Images belonging to the diffuse illumination class are used in cross-correlation processing. Finally, an operative procedure is presented for applying the automated ICC processing chain in geoscience monitoring applications.

scholarly journals Embodied lenses for collaborative visual queries on tabletop displays

2012 ◽  
Vol 11 (4) ◽  
pp. 319-338 ◽  
Author(s):  
KyungTae Kim ◽  
Niklas Elmqvist
Keyword(s):  
Formative Evaluation ◽  
User Study ◽  
Conceptual Models ◽  
Virtual Space ◽  
Multidimensional Data ◽  
Physical Interaction ◽  
Tabletop Displays ◽  
Multidimensional Data Visualization ◽  
Diffuse Illumination ◽  
Free Interaction

We introduce embodied lenses for visual queries on tabletop surfaces using physical interaction. The lenses are simply thin sheets of paper or transparent foil decorated with fiducial markers, allowing them to be tracked by a diffuse illumination tabletop display. The physical affordance of these embodied lenses allow them to be overlapped, causing composition in the underlying virtual space. We perform a formative evaluation to study users’ conceptual models for overlapping physical lenses. This is followed by a quantitative user study comparing performance for embodied versus purely virtual lenses. Results show that embodied lenses are as efficient as purely virtual lenses, and also support tactile and eyes-free interaction. We then present several examples of the technique, including image layers, map layers, image manipulation, and multidimensional data visualization. The technique is simple, cheap, and can be integrated into many existing tabletop displays.

Spatial and temporal response properties of residual vision in a case of hemianopia

1994 ◽  
Vol 343 (1304) ◽  
pp. 157-166 ◽  
Keyword(s):  
Striate Cortex ◽  
Light Flux ◽  
Spatial Summation ◽  
Light Scatter ◽  
Temporal Response ◽  
Rapid Loss ◽  
Residual Vision ◽  
Spatial Frequencies ◽  
Diffuse Illumination ◽  
Peak Sensitivity

Residual vision in subjects with damage of the primary visual cortex (striate cortex) has been demonstrated in many previous studies and is taken to reflect the properties of known subcortical and extrastriate visual pathways. In this report we describe psychophysical experiments carried out on a subject clinically blind in half of his visual field (i.e. homonymous hemianopia) caused by striate cortex dam age. They reveal the existence of two distinct channels mediating such vision. One channel responds to spatial structure and the other to light flux changes. The spatially tuned channel has a peak response at about 1.2 cycles per degree and shows rapid loss of sensitivity at both high and low spatial frequencies. This channel does not respond to diffuse illumination. The light flux channel, however, responds only to sudden increments in light flux levels on the retina and shows extensive spatial summation. Both channels require transient inputs, with a peak sensitivity at about 10 cycles per second and show virtually complete attenuation at temporal frequencies below 2 cycles per second. The spatiotemporal characteristics of these two channels account for much of the reported limits of visual performance attributed to subcortical or extrastriate pathways in some patients, and especially for their relatively good sensitivity for the detection of abrupt, transient stimuli or fast-moving targets. A new method is also applied to the m easurement of the amount of light scatter in the eye. The measurements show that light scatter into the sighted hemifield could not account for the results obtained with the stimuli used to characterize the residual vision of this subject.

scholarly journals Sun and sky: Does human vision assume a mixture of point and diffuse illumination when interpreting shape-from-shading?

2011 ◽  
Vol 51 (21-22) ◽  
pp. 2317-2330 ◽  
Author(s):  
Andrew J. Schofield ◽  
Paul B. Rock ◽  
Mark A. Georgeson
Keyword(s):  
Shape From Shading ◽  
Human Vision ◽  
Diffuse Illumination

Design of folded holographic spectrum-splitting photovoltaic system for direct and diffuse illumination conditions

2014 ◽  
Author(s):  
Yuechen Wu ◽  
Shelby D. Vorndran ◽  
Juan M. Russo ◽  
Silvana Ayala ◽  
Raymond K. Kostuk
Keyword(s):  
Photovoltaic System ◽  
Spectrum Splitting ◽  
Diffuse Illumination

Atmospheric ozone concentration and the colour vision of insect pollinators

1999 ◽  
Vol 47 (5) ◽  
pp. 529 ◽  
Author(s):  
Adrian G. Dyer ◽  
Adrian G. Dyer
Keyword(s):  
Theoretical Model ◽  
Ozone Concentration ◽  
Colour Vision ◽  
Atmospheric Ozone ◽  
Large Reduction ◽  
Minimal Effect ◽  
Colour Space ◽  
Diffuse Illumination ◽  
Insect Pollinators

Using a theoretical model of honeybee colour vision, and considering direct and diffuse illumination conditions, it is shown that a large reduction in atmospheric ozone concentration would have a minimal effect on bee colour vision over the whole of their colour space.

Sign in / Sign up

Export Citation Format

Share Document