PLS 2016: Pedestrian vision at night
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Pedestrian Vision at Night Navaz Davoudian & Peter Raynham
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Transcript of PLS 2016: Pedestrian vision at night
Pedestrian Vision at Night
Navaz Davoudian & Peter Raynham
Assumed Pedestrian Needs Caminada and van Bommel classified the requirements for lighting in residential roads into four sections:
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•Detection of obstacles •Identification of persons
• Visual orientation •Pleasantness and comfort
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Avoiding obstacles
Visual orientation
Facial Recognition
• Alerts pedestrian to take evasive or defensive
action.
• 4m to 10m being suggested as the ideal distance
for face recognition.
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Pleasantness and comfort
• Freedom from glare – 2 metrics in use:– Luminous Intensity Classes– Glare Index Classes
• Concept of “pleasantness”
Metrics are not a good way to control discomfort glare with is largely a function of source luminance
EN13201-2:2015:P Classes
BS5489-1 White Light Mesopic Vision
derived from ILP PLG03
PLG03 – Table1
PLG03 - Assumptions
• All visual activity on the road• Road has q0 of 0.07• Average illuminance not minimum considered
Are these assumptions sensible?
Davoudian & Raynham (2012)What do pedestrians look at at night?
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What do people Look at at night?
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• Eye Tracking Study on the Importance of Different Visual Tasks for the Pedestrians at Night
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What do people Look at at night?
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What do people Look at at night?• S1• 15 lx
Lighting Class
• 3.5-5.2 mPavement
width
• LowObstacle
level
• S3• 7.5 lx
Lighting Class
• 2 mPavement
width
• ModerateObstacle
level
• S4• 5 lx
Lighting Class
• 2 mPavement
width
• HighObstacle
level
What do people Look at at night?
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What do people Look at at night?
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40-50 %At the ground
What do people Look at at night?
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40-50 %At the ground
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What do people Look at at night?
What do people look at at night?
Where do people look at at night?
Detailed Image Analysis
Extract individual image from videoSample every 100 ms
Process image to make it lighter
Locate point of fixation
Assign direction of travel
Assign nominal horizon
Calculate coordinates in street frame of reference
Calculate coordinates in street frame of reference
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Where people look at at day time
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Where people look at at night
Results:• We know where people are looking:
– Can measure luminance and hence adaption– Which surface need lighting
• Reduced field of view– Objects with reduced visual saliency– Low luminance of objects
• Vertical illuminance very important
What next
• Luminance measurement• Assess threshold for visual saliency• Re-assess photometric distribution of lanterns
Questions
[email protected]@ucl.ac.uk
UCL Institute for Environmental Design and EngineeringCentral House, 14 Upper Woburn PlaceLondon WC1H 0NN
