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 Federal Highway Administration > Publications > Research Publications > Safety > 03065 > In-Vehicle Display Icons and Other Information Elements: Volume I
Publication Number: FHWA-RD-03-065
Date: September 2004

In-Vehicle Display Icons and Other Information Elements: Volume I

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CHAPTER 11: LIST OF EQUATIONS

Determining the Appropriate Luminance Uniformity within an Icon

 Perent Element (Luminance min) - (Luminance max) (1) = Nonuniformity (Luminance max) where Luminance max = the smaller luminance value Luminancemin = the greater luminance value

Determining the Appropriate Contrast within an Icon

 We define contrast as a ratio between maximum and minimum luminance values, or: (2) Contrast ratio =      Luminance max Luminance min where: Luminance max = luminance emitted by the area or element of greater intensity Luminance min = luminance emitted by the area or element of smaller intensity

Determining the Appropriate Size of Icon Components

If Known Use These Formulas for Calculating These Known Years
Visual Angle Symbol Height Distance

Distance and

Symbol Height

(3)

(4)

Distance and

Visual Angle

Distance x [Tangent (Visual Angle)]

(5)

Visual Angle and

Symbol Height

Symbol Height

Tangent (Visual Angle)

(6)

Symbol Height = the Height of the symbology

Distance = distance from viewer's eyepoint to the display

Visual Angle = angle in degrees

Height and Distance use the same unit of measure (e.g., meters, yards, etc.)

Determining The Effects of Icon Legibility

S=KOm

Perceived Urgency of Auditory Signals

 Example of Using Steven's Power Law for Producing Urgency Exponents (see references 2 and 3 for more detailed explanations and examples) S=kOm (8)