Colourwash Floodlighting of Lighthouses By Malcolm Nicholson, - - PowerPoint PPT Presentation

Colourwash Floodlighting of Lighthouses

By Malcolm Nicholson, Principal Development Engineer, AFRIN

Royal Institute of Navigation NAV10 2nd December 2010

Introduction

Use of modern Radionavigation Technology Growth in Coastal Background Lighting The GLA’s require a method to provide a quick visual confirmation One method is to colour-wash or floodlight the existing structure In order to –

Determine the most effective colour Determine the most effective geometry Determine the required illumination

Methods - Colour

• Initial feasibility studies indicated

that colour contrast was the dominant factor

• Six 200W RGB LED Floodlights

were used

Floodlight Software setting to achieve colours (%) Colour R G B Blue 100 Orange 50 100 Green 100 Cyan 100 100 Magenta 100 100 Yellow 100 50 White 100 100 100 Red 100

Methods - Geometry

• Three down lighters angled at

50o at 1.5m

• Three up lighters angled at

45o at 3m

Method - Illumination Three trials First trial ¼ intensity Second trial ½ intensity Third trial full intensity

• Intensities controlled by software

Observations

• Four experienced observers
• On board THV Alert at a distance
• f 2M
• 72 observations were made

Light 1 Excellent Very Good Good Acceptable Poor Very Poor Unacceptable Colour Brightness Conspcuity Confidence Comments

Results and Interpretation – 1st Trial

Confidence Conspcuity Brightness Colour

BB3 BT3 BA6 OB3 OT3 OA6 GB3 GT3 GA6 CB3 CT3 CA6 MB3 MT3 MA6 YB3 YT3 YA6 WB3 WT3 WA6 RB3 RT3 RA6

Unacceptable Excellent Acceptable Observers Score Floodlight Colours

Results and Interpretation – 2nd Trial

Confidence Conspcuity Brightness Colour

BB3 BT3 BA6 OB3 OT3 OA6 GB3 GT3 GA6 CB3 CT3 CA6 MB3 MT3 MA6 YB3 YT3 YA6 WB3 WT3 WA6 RB3 RT3 RA6

Unacceptable Excellent Acceptable Observers Score Floodlight Colours

Results and Interpretation – 3rd Trial

Confidence Conspcuity Brightness Colour

BB3 BT3 BA6 OB3 OT3 OA6 GB3 GT3 GA6 CB3 CT3 CA6 MB3 MT3 MA6 YB3 YT3 YA6 WB3 WT3 WA6 RB3 RT3 RA6

Unacceptable Excellent Acceptable Observers Score Floodlight Colours

Measurements and Calculations

• Intensity measurements were

carried on the R&RNAV light range facility in Harwich

γ

3 2 cos

D I Ep =

π ρ E L =

m^2 0.78 Downlit Beam Area m 1.60 Downlit Beam Height 0.89 Cos A * Cos B m 0.49 Downlit Beam Width 0.91 Cos B m^2 2.91 Uplit beam area 0.98 Cos A m 3.10 Uplit Beam Height 25 B m 0.94 Uplit Beam width 12 A Floodlight Beam Area

Analysis

Pulsar Chromahood 200 Cyan Intensity (cd) Geometry (Degrees) Distance (m) Reflection Factor Illum (Lux) Lumin (Cd/m^2) Surface Area (m^2) Intensity (cd) Illum at the Observer (Lux)

Angular Subtense at 2M (minutes of arc) Up Lighters

4.8

Down Lighters

1.4

Combined

6.2

Full Power Uplit Downlit Combined 10489 10489 20978 45 50 3 1.50 0.75 0.75 812 3248 4060 194 775 969 2.91 0.78 3.70 1694.55 1823.65 3518.20 1.24E-04 1.33E-04 2.56E-04

Conclusions

• It can be seen from the results that the floodlighting of lighthouses can be effective

as a short range AtoN to give the mariner a quick, recognisable fixed point of reference.

• In this trial, cyan was the most recognisable colour, appeared to be the brightest,

was the most conspicuous and instilled the most confidence as an AtoN.

• The green and red colours used in the trial, although effective may be confusing to

mariners because of the lateral significance associated with these colours.

• The blue colour used in the trial, although effective as a colour does not lend itself to
• utlining of shapes because of the perceived blurring effect.
• Similarly magenta although effective as a colour does not lend itself to floodlighting

because of atmospheric scattering.

• The colours orange, yellow and white used were not perceived as suitable colours in

this trial because they did not provide enough colour contrast with the adjacent street lighting.

• The shape of the floodlit structure should subtend a minimum angle of 3 minutes of

arc at the eye of the observer, at the maximum distance of recognition, in order for the observer to recognise shape.

• Between 60 and 120 microlux illuminance at the eye of the observer was required

for the acceptable recognition of the lighthouse tower in this trial.

Thank you for you attention

Malcolm.nicholson@gla-rrnav.org