Visibility of Displayed Information

Carlson, Curtis R.; Cohen, Roger W.

doi:10.21236/ada063009

Cited by 14 publications

(3 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As particles are added to the atmosphere, at some point the observer will notice a change in the clarity of the scene. This level is one JND (Carlson and Cohen 1978). As particles continue to be added, a level will be reached at which another change is just noticeable.…”

Section: Interpretation Of the Vitmentioning

confidence: 99%

Guidelines for evaluating air pollution impacts on class I wilderness areas in California

Peterson¹,

Schmoldt²,

Eilers³

et al. 1992

View full text Add to dashboard Cite

Section: Interpretation Of the Vitmentioning

confidence: 99%

Guidelines for evaluating air pollution impacts on class I wilderness areas in California

Peterson¹,

Schmoldt²,

Eilers³

et al. 1992

View full text Add to dashboard Cite

“…In this earlier article, a percent change in b ext was recommended as a metric for progress toward the national goal of no manmade visibility impairment. Pitchford et al 4 take the derivation one step further by introducing the parameter X, which is the ratio of the sight path length r to the visual range VR X = r/VR (10) and making use of the Koschmieder relation for the visual range -lnε = VR b ext (11) where ε is the liminal (threshold) contrast. For example, if the liminal contrast is 2%, -lnε is equal to 3.91.…”

Section: A2 Interpretation By Pitchford Et Almentioning

confidence: 99%

Use of the Deciview Haze Index as an Indicator for Regional Haze

Richards

1999

Journal of the Air & Waste Management Association

View full text Add to dashboard Cite

The U.S. Environmental Protection Agency (EPA) Notice of Proposed Rulemaking (NPR) for regional haze uses the deciview haze index (dv) as the indicator for visibility impairment and proposes a change of 1 dv as "a small but noticeable change in haziness under most circumstances." All previous visibility rules have specified human perception as the indicator for visibility impairment. This article examines the technical basis cited in the NPR for this new indicator for visibility impairment and for the perception threshold of approximately 1 dv. Derivations based on the assumptions and approximations cited in the NPR show that the deciview haze index does not have the correct functional form to relate changes in haze within federal Class I areas to the visual perception of those changes. The just-noticeable change in light extinction is, in most cases, inversely proportional to the sight path length instead of proportional to the light-extinction coefficient. These derivations also indicate that a 1-dv change in haziness is typically too small to be perceived in most Class I areas.

show abstract

“…3 The improvement in viewable contrast beyond that by simply applying increased brightness diminishes rapidly. With this in mind it is no wonder that the push in the industry is toward brighter projectors.…”

Section: Screenmentioning

confidence: 99%

<title>Projection system design: display device and system performance trade offs</title>

Salsman

1997

SPIE Proceedings

View full text Add to dashboard Cite

Since the advent ofradar in the 1940's there has been an increasing number of systems requiring the display of information to various levels of the military command structure. However, display technology has been a limiting factor in designing military systems. Cathode ray tubes (CRTs) are sensitive to vibration, are affected by the earth's magnetic field, require high voltage, emit RF signals, and are bulky and heavy. The military has been the foremost funding sources of display technology development here in the US. With the development of flat panel display technologies the military has fmally been able to incorporate displays in field portable equipment, however these displays have limitations in brightness, ruggedness, and other factors that are problems in several key applications. One ofthese issues is the size limitation of flat panel displays. One of the compensating approaches taking a leap forward in application is the use of flat panel displays in projection systems. This paper will review the tradeoffs in these projectors, the interaction between sub-system component groups, design issues affecting ruggedness, and the performance ofthe final projector. In addition, a discussion is included on the impact of ambient light on the applicability of front and rear projection systems. WHY PROJECTION?C31, traffic control, asset analysis, briefmg, training, and many other applications require the use of display technology capable ofpresenting information to groups ofpeople. In most ofthese cases the environment has at least moderate lighting control. CRTs provide a good high resolution image, but in large formats they become unwieldy and are very limited in ruggedness. In projection mode the CRT has size, weight and alignment stability issues. An alternative to the CRT are large format flat panel displays, which suffer from weight, mechanical stability, and fragility. It is easy to imagine what would happen to a 40 inch diagonal flat panel display, composed of 60 mil glass, inside a command center that was air dropped into position, or mounted in a command vehicle that is moving rapidly over rough terrain. Large format direct view displays which need electrical connection over their entire surface, must be made from rigid brittle material and are therefore extremely fragile.Projection systems provide a method to present information to a group ofpeople in a small rugged package. The external system components for front projection consist of a computer or video system, that is militarized by their manufacturer, and a screen which can be anything from a white wall to a sheet of material with reflective gain and polarity control. The large sized components of a projection system are typically a sheet ofplastic or other extremely stable material. In rear projection systems the projection path is usually folded so the external components from the image generator consist ofa plastic screen and mirrors, the later which can be made from stretched silvered milar. This approach also utilizes inert large format component...

show abstract

Visibility of Displayed Information

Cited by 14 publications

References 17 publications

Guidelines for evaluating air pollution impacts on class I wilderness areas in California

Guidelines for evaluating air pollution impacts on class I wilderness areas in California

Use of the Deciview Haze Index as an Indicator for Regional Haze

<title>Projection system design: display device and system performance trade offs</title>

Contact Info

Product

Resources

About