Sources & Surfaces Evaluating Spectral Distribution Interactions Using Roadway Signage IESNA Roadway Lighting Committee April 2003 David M. Keith, FIES.

Sources & Surfaces Evaluating Spectral Distribution Interactions Using Roadway Signage IESNA Roadway Lighting Committee April 2003 David M. Keith, FIES & Jefferey F. Knox

Sources & Surfaces: Overview Our world is not all shades of gray, but... “Lumen” is spectrally ignorant by definition Therefore, since we use color to communicate especially important information such as should we evaluate visibility using full spectral information that describes color?

Sources & Surfaces: Background Luminous reflectance: Any of the geometric aspects of reflectance in which both the incident and the reflected flux are weighted by the spectral luminous efficiency of radiant flux V(λ). Note: Unless otherwise qualified, the term “reflectance” means luminous reflectance. Sources: “GLOSSARY OF LIGHTING TERMINOLOGY” IESNA Lighting Handbook, 9th edition & IENSA RP-16-1996

Sources & Surfaces: Background Reflectance = Lumens off  Lumens on This means that “reflectance” is specific to each source’s spectral power distribution’s interaction with the surface’s spectral reflectance distribution Contrast is calculated using reflectance

Sources & Surfaces: Background Reflectance for surfaces is typically reported with no mention of the source being used in the evaluation, e.g. Figure 1-36, IESNA Lighting Handbook, 9th edition ANSI/IESNA RP-8-00 luminance calculation procedures (Annex A & IESNA Handbook, Figure 22-1)

Sources & Surfaces: Background Reflectance for many (most?) exterior surfaces is only marginally dependent on source SPD, because most natural surfaces are approximately “gray” Colored surfaces may be dependent on SPD interactions - how to find out? Roadway signage is familiar, available & important example for such investigation

Sources & Surfaces: Procedure Collect spectral data for exterior light sources and signage surfaces Combine using spectrally informed procedures to establish reflectances Combine into appropriate pairs for calculating contrast values Repeat with CIE LAB procedures for color difference evaluations

Sources Used in this Work Equal Energy constant radiation across the entire spectrum D65 a ‘daylight’ source of 6500 K from CIE Illuminant A an incandescent source of 2850 K from CIE HPS SPDs of four High Pressure Sodium wattages MH SPDs for Metal Halide Sources 250 or 400 watt, universal or horizontal Fluorescents four different CCT’s: 30, 35, 41 & 65

Sources Used in this Work SourceAbbr. x yCCTCRI Equal EnergyEqE0.330.33545595* CIE D65C_D0.310.336502100 CIE Illuminant AC_A0.450.412856100 HPS 100WH100.520.42206016 HPS 150WH150.510.42217421 HPS 250WH250.520.41200121 HPS 400WH400.520.42211616 MH 250W HorizM2h0.390.40400264* MH 250W UnivM2u0.380.40406153* MH 400W HorizM4h0.370.39431968* MH 400W UnivM4u0.400.40377658* Fluorescent 3000KF300.440.41291985 Fluorescent 3500KF350.420.40332687 Fluorescent 4100KF410.390.38381387 Fluorescent 6500KF650.320.34608887

Surfaces Used in this Work Roadway signage films manufactured materials, not paints Three different series from 3M Engineer Grade (ENG) High Intensity Flexible Workzone Sheeting (HIS) Visual Impact Sheeting (VIS) a.k.a. Scotch Lite Diamond Grade

Surfaces Used in this Work each series has multiple colors white yellow red green blue two series (HIS & EG) also have brown orange

Surfaces Used in this Work All meet FHWA Specifications CIE D65 CIE Illuminant A x y x y WhiteENG 0.320.34 0.450.41 HIS 0.310.33 0.440.41 VIP 0.310.33 0.440.41 BlueENG 0.140.11 0.160.18 HIS 0.140.13 0.150.22 VIP 0.150.13 0.160.24 GreenENG 0.140.42 0.180.51 HIS 0.140.44 0.170.53 VIP 0.130.42 0.170.51 YellowENG 0.500.48 0.550.44 HIS 0.520.47 0.570.43 VIP 0.530.47 0.570.43 OrangeENG 0.580.40 0.610.39 HIS 0.540.40 0.600.39 RedENG 0.660.33 0.680.32 HIS 0.660.32 0.680.32 VIP 0.660.32 0.680.32 BrownENG 0.520.40 0.590.39 HIS 0.500.40 0.580.39

Procedure: Reflectance Lumens on Lumens on = K*  [S( )*v( )] Lumens off Lumens off typical = ρ average * {K*  [S( )*v( )]} Lumens off revised = K *  [ S( ) * v( ) * ρ ( ) ]

Reflectances EqE C_D C_A H10 H15 H25 H40 M2h M2u M4h M4u F30 F35 F41 F65 White ENG 45 45 4545 45 45 4545 45 45 4545 45 45 45 HIS 33 33 3333 33 33 3333 33 33 3333 33 33 33 VIP 41 42 4141 41 41 4141 41 41 4141 41 41 42 Blue ENG 2.4 2.6 1.50.7 0.8 0.8 0.81.8 1.5 1.9 1.61.1 1.3 1.5 2.1 HIS 3.3 3.5 2.20.8 0.9 0.8 0.92.4 2.2 2.6 2.21.8 2.1 2.3 3.1 VIP 1.9 2.1 1.30.5 0.6 0.5 0.61.5 1.4 1.6 1.31.2 1.4 1.5 1.9 Green ENG 5.5 5.9 4.11.6 1.7 1.6 1.64.4 4.0 4.7 4.03.8 4.1 4.5 5.5 HIS 6.2 6.6 4.61.5 1.7 1.6 1.64.9 4.4 5.2 4.44.5 4.9 5.3 6.5 VIP 5.6 6.0 4.21.6 1.7 1.6 1.64.5 4.0 4.8 4.03.8 4.2 4.5 5.6 Yellow ENG 37 35 4148 48 48 4840 42 40 4142 41 40 37 HIS 18 17 2125 25 25 2520 21 20 2121 20 20 18 VIP 26 25 3037 37 37 3730 31 29 3130 29 28 26 Orange ENG 25 23 3144 43 44 4430 31 29 3128 26 25 20 HIS 17 16 2026 25 26 2619 19 18 2020 19 18 16 Red ENG 6.1 5.4 8.57.8 7.4 8.3 7.55.1 4.5 5.0 5.18.4 7.7 7.1 5.5 HIS 4.2 3.7 5.85.7 5.4 6.1 5.53.7 3.3 3.6 3.75.7 5.3 4.8 3.7 VIP 6.7 5.9 9.58.8 8.4 9.5 8.55.5 4.8 5.4 5.59.8 9.0 8.3 6.3 Brown ENG 5.8 5.5 6.97.5 7.3 7.6 7.46.0 5.9 5.9 6.17.2 6.9 6.6 5.9 HIS 4.5 4.3 5.36.3 6.1 6.3 6.24.9 5.0 4.8 5.05.0 4.8 4.7 4.2

Reflectances: HPS vs MH High Pressure SodiumMetal Halide AvgStDevAvgStDev HPS/MH White ENG450.0450.01.0 HIS33 0.0330.01.0 VIP410.1410.01.0 Blue ENG0.80.11.70.20.5 HIS0.80.12.40.20.4 VIP0.50.11.50.10.4 Green ENG1.60.04.30.30.4 HIS1.60.14.70.40.3 VIP1.60.04.30.40.4 Yellow ENG480.1 411.01.2 HIS 250.2200.51.2 VIP370.2300.81.2 Orange ENG440.7301.01.5 HIS260.4190.51.4 Red ENG7.80.44.90.31.6 HIS5.7 0.33.60.21.6 VIP8.80.55.30.31.7 Brown ENG7.50.16.00.11.2 HIS6.20.14.90.11.3

Procedure: Contrast C = (L max - L min ) / (L max ) C mod = (L max - L min ) / (L max + L min ) For a perfectly diffuse reflector (or surfaces with similar reflectance geometric properties) Luminance = Exitance   Exitance = Lumens on * Reflectance C = (ρ max - ρ min ) / (ρ max ) C mod = (ρ max - ρ min ) / (ρ max + ρ min ) Still calculated in lumens (more accurately determined)

Procedure: Contrasts Color pairs determined by common sign combinations white - red(Stop, Yield, One-way) black - orange(work/construction, detour) black - yellow(caution, warning, advisory) white - green(information, direction, exit) Combinations evaluated using sign films in the same series e.g. ENG red & ENG white, HIS red & HIS white, VIP red & VIP white

Procedure: Color Difference Color Difference Threshold The difference in chromaticity or luminance between two colors that makes them just perceptibly different. The difference may be in hue, saturation, brightness (lightness for surface colors) or a combination of the three. This model more accurately reflects foveal vision which does not see in black & white - for example observe the horizontal line above - as it shades from black to white, it remains visible against the colored background (or does it?)

Procedure: CIE L*a*b* First, the illuminant in the local context can be specified, also in terms of the R, G and B cone outputs, as a reference white. The model treats all colors as a combination of surface color and illuminant color, which allows the model to be applied across a wider range of viewing conditions. Second, the trichromatic XYZ "primaries" are transformed mathematically to represent the Y/B and R/G opponent dimensions (along with a lightness or white/black dimension), which allows the models to reproduce the basic structure of color experience.

Procedure: CIE L*a*b* Finally, CIELAB is based on a set of imaginary “primary” lights that have been chosen specifically to make the color space perceptually uniform (at least, to the degree possible in a three dimensional model). That is, a difference of 10 units on the lightness dimension has the same perceptual impact as a 10 unit difference on the Y/B or R/G dimensions -- either separately or in combination. delLAB (ΔLAB) is the Euclidean distance between two color loci in the CIE L*a*b* space ΔLAB = {(ΔL) 2 + (Δa) 2 + (Δb) 2 } 1/2

C & delLAB: white - red ENG Series HIS Series VIP Series Source C Cmod dLAB C Cmod dLAB C Cmod dLAB EqE 0.86 0.76 82 0.87 0.77 64 0.84 0.72 87 C_D 0.88 0.78 82 0.80 0.80 74 0.86 0.75 87 C_A 0.81 0.68 85 0.82 0.70 77 0.77 0.62 92 H10 0.83 0.70 68 0.83 0.70 63 0.78 0.64 74 H15 0.83 0.72 69 0.83 0.72 64 0.79 0.66 75 H25 0.81 0.69 70 0.81 0.69 64 0.77 0.62 76 H40 0.83 0.71 68 0.83 0.71 63 0.79 0.66 74 M2h 0.89 0.80 74 0.89 0.80 65 0.87 0.76 78 M2u 0.90 0.82 70 0.90 0.82 63 0.88 0.79 73 M4h 0.89 0.80 74 0.89 0.80 67 0.87 0.77 78 M4u 0.89 0.80 71 0.89 0.80 64 0.87 0.76 74 F30 0.81 0.68 81 0.83 0.70 73 0.76 0.62 89 F35 0.83 0.71 81 0.84 0.72 74 0.78 0.64 89 F41 0.84 0.73 81 0.85 0.75 74 0.80 0.67 89 F65 0.88 0.78 81 0.89 0.80 73 0.85 0.74 86

C & delLAB: black - orange ENG Series HIS Series Source C Cmod dLAB C Cmod dLAB EqE 0.92 0.85 102 0.88 0.79 73 C_D 0.91 0.84 101 0.88 0.78 71 C_A 0.94 0.88 112 0.90 0.82 81 H10 0.95 0.91 120 0.92 0.86 85 H15 0.95 0.91 118 0.92 0.85 83 H25 0.95 0.91 119 0.92 0.86 85 H40 0.95 0.91 119 0.92 0.86 85 M2h 0.93 0.87 108 0.89 0.81 75 M2u 0.93 0.88 107 0.90 0.82 72 M4h 0.93 0.87 107 0.89 0.80 74 M4u 0.94 0.88 108 0.90 0.81 75 F30 0.93 0.87 110 0.90 0.82 80 F35 0.92 0.86 109 0.90 0.81 78 F41 0.92 0.85 106 0.89 0.80 78 F65 0.90 0.82 100 0.87 0.77 72

C & delLAB: black - yellow ENG Series HIS Series VIP Series Source C Cmod dLAB C Cmod dLAB C Cmod dLAB EqE 0.95 0.90 111 0.89 0.80 91 0.92 0.86 106 C_D 0.94 0.89 108 0.89 0.79 89 0.92 0.85 105 C_A 0.95 0.91 112 0.90 0.82 94 0.93 0.88 110 H10 0.96 0.92 121 0.92 0.85 101 0.95 0.90 117 H15 0.96 0.92 120 0.92 0.85 100 0.95 0.90 116 H25 0.96 0.92 121 0.92 0.85 101 0.95 0.90 118 H40 0.96 0.92 121 0.92 0.85 101 0.95 0.90 118 M2h 0.95 0.91 114 0.90 0.82 94 0.93 0.87 110 M2u 0.95 0.91 117 0.90 0.82 95 0.93 0.88 111 M4h 0.95 0.90 113 0.90 0.82 94 0.93 0.87 109 M4u 0.95 0.91 116 0.90 0.82 96 0.93 0.88 111 F30 0.95 0.91 114 0.91 0.83 95 0.93 0.88 109 F35 0.95 0.91 114 0.90 0.82 95 0.93 0.87 110 F41 0.95 0.91 114 0.90 0.82 94 0.93 0.87 108 F65 0.95 0.90 111 0.89 0.80 90 0.92 0.86 104

C & delLAB: white - green ENG Series HIS Series VIP Series Source C Cmod dLAB C Cmod dLAB C Cmod dLAB EqE 0.88 0.78 72 0.81 0.68 71 0.87 0.76 72 C_D 0.87 0.77 71 0.80 0.67 69 0.86 0.75 72 C_A 0.91 0.83 74 0.86 0.75 71 0.90 0.81 73 H10 0.96 0.93 73 0.95 0.91 65 0.96 0.92 69 H15 0.96 0.93 72 0.95 0.90 65 0.96 0.92 68 H25 0.96 0.93 73 0.95 0.91 65 0.96 0.92 68 H40 0.96 0.93 73 0.95 0.91 65 0.96 0.92 69 M2h 0.90 0.82 71 0.85 0.74 68 0.89 0.80 69 M2u 0.91 0.84 68 0.87 0.76 64 0.90 0.82 67 M4h 0.90 0.81 71 0.84 0.73 69 0.88 0.79 70 M4u 0.91 0.84 69 0.87 0.76 66 0.90 0.82 68 F30 0.91 0.84 68 0.86 0.76 65 0.91 0.83 66 F35 0.91 0.83 67 0.85 0.74 65 0.90 0.81 66 F41 0.90 0.82 68 0.84 0.72 65 0.89 0.80 67 F65 0.88 0.78 67 0.80 0.67 65 0.87 0.76 69

“How to use these results” If signs are “iconic” - the image is what matters, not the information within - then reflectance of the surface should be maximised contrast and delLAB values are not as important Stop signs’ highest reflectance from C_A and HPS If signs are “informational” (read text) then reflectance is not as important contrast and delLAB should be maximized work, caution and “direction/exit” colors have highest values from HPS (nearly as high for C_A)

Future Work Investigate additional colors and surfaces Incorporation of appropriate mesopic spectral luminous efficiency function(s) for foveal vision Application of a model for evaluating age effects Further investigate appropriate color difference models (such as CIE LAB)

Summary Keep the spectral information in the calculation procedure Spectral effects of illuminants cannot be evaluated without considering the spectral reflectance of the lighted surfaces All this is evaluated as single bounce applications (no inter-reflections!)

Sources & Surfaces This work was solely supported by Luminous Design, Inc & Marshall Design, Inc who gratefully acknowledge the assistance of: 3M for data on signage reflectance Philips Lighting for lamp SPD’s email: keithd@resodance.com

Sources & Surfaces Evaluating Spectral Distribution Interactions Using Roadway Signage IESNA Roadway Lighting Committee April 2003 David M. Keith, FIES & Jefferey F. Knox

Sources & Surfaces Evaluating Spectral Distribution Interactions Using Roadway Signage IESNA Roadway Lighting Committee April 2003 David M. Keith, FIES.

Similar presentations

Presentation on theme: "Sources & Surfaces Evaluating Spectral Distribution Interactions Using Roadway Signage IESNA Roadway Lighting Committee April 2003 David M. Keith, FIES."— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Sources & Surfaces Evaluating Spectral Distribution Interactions Using Roadway Signage IESNA Roadway Lighting Committee April 2003 David M. Keith, FIES.

Similar presentations

Presentation on theme: "Sources & Surfaces Evaluating Spectral Distribution Interactions Using Roadway Signage IESNA Roadway Lighting Committee April 2003 David M. Keith, FIES."— Presentation transcript:

Similar presentations

About project

Feedback