How linear visual aids restore nighttime depth perception
At night, everyone loses their depth perception.
with point source visual aids, since one often cannot tell which light is beside or in front of another, point source visual aids often Cause confusion at night.
Therefore, They provide a minimum of confusing flight information to pilots.
Linear visual aids restore pilots' nighttime depth perception. from a distance at night, the liniarity provides lit angles which the brain interprets and provides depth and dimension to the helipad.
Depth perception and dimension, allow pilots to gauge KEY VECTORS like;
distance;
closing speed;
height;
ANGLE OF APPROACH;
Orientation
Drift
and other key vectors,
all are used by pilots in daylight so are important for improving nighttime helipad safety.
to illustrate; BELOW ARE IDENTICAL PHOTOGRAPHS. ALL THAT HAS CHANGED IS THAT THEY HAVE BEEN DARKENED TO MAKE THE HELIPADS MORE DIFFICULT TO SEE. representing the point source lights at night are the darkened photos illustrating how everyone loses their depth perception at night.
NOTE: what is Important for good visibility, is having a good contrast between what one is trying to see and its background.
As the pictures below and these colored letters try to illustrate when one loses contrast AND DEPTH PERCEPTION, everything becomes more difficult to see OR UNDERSTAND, especially from a distance.
Again, below are Identical Pictures, But One Has Been Darkened to Represent Lost Nighttime Depth Perception.
The picture below is taken right next to a fully compliant FAA / ICAO helipad, with all its point source lights lit.
Because the picture has been darkened, there are no visual references other than the point sources. Because everyone loses their depth perception at night, and point source lights all look the same no matter the viewing angle (one cannot tell which light is next to or behind another), all one sees is a confusing pattern of point source lights. Despite being right next to the helipad, it is even difficult here to make out where the lit helipad is located.
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Fully Compliant FAA / ICAO Helipad Lighting;
which is difficult to see or understand even when the above picture is taken right next to the helipad!
The Same Fully Compliant FAA / ICAO Helipad Lighting with more ambient light. The point source lights are still somewhat confusing, however, their pattern can be more easily made out because of the concrete pad and its painted markings.
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With more ambient light on the subject and BETTER CONTRAST, it is easier to see the light pattern and tell what they mean. Especially when the concrete pad, its painted markings, the grass and other colours all become visible. However, even here, with much more ambient light and standing right next to the helipad, the point sources are still somewhat confusing. This confusion disappears with linear sources.
Below are pictures of a joint FAA and Port Authority of New York and New Jersey (PANYNJ) of a Linear Visual Aid Research project January 1999, at The Downtown Manhattan Helipad. (Video by PANYNJ).
This research was detailed and published by the FAA at The FAA Heliport Vertiport Lighting Conference Proceedings,
Nov 1999 (DOT/FAA/ ND 99/1) .
(Note: The helipad below meets all FAA regulations, yet, at night, standing close to the helipad, the pattern of lights is very confusing. For pilots from a distance, if they were approaching the helipad at low angles, these point source visual aids would be even more confusing and their pattern even more difficult to make out.)
At Night, Everyone Loses Their Depth Perception with point sources, Unless One Is Above Or Looking PARALLEL Along Them As One Can Not Tell Which Light Is Next To or Behind Another. THIS Causes Confusion!
Below is the PANYNJ Downtown Manhattan helipad, with point sources.
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The same picture with both point sources and linear visual aids.
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The same picture now without the point sources having just the linear visual aids.
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Even though all the pictures remain very dark, this early extruded linear LEDline®, although much less bright than today's linear LEDline®clearly demonstrates that: • Because of the linearity, linear visual aids provide for immediate recognition of the helipad’s area/dimension. There is no
doubt, hesitation, or confusion once there are no point source points of light. • Therefore, since there is no confusion, linear visual aids provide for a much better nighttime definition / dimension of
any helipad.
• Linear visual aids, because their aspect changes with the viewing angle, restore lost nighttime depth perception and
viewers never have any doubt as to what they are looking at or where the helipad is. (Note: Even when viewed at shallow
angles, the linearity still provide viewers with much improved depth and dimension.
Further Evidence: Below are a series of blue point source lights from the same helipad, which, when viewed from a distance, are difficult to see what they represent. Indeed, it is clear that these blue point source lamps, provide NO depth perception for viewers, yet the linear visual aids outlining the helipad allow pilots to fully judge all their daytime flying vectors like closing speed; height; approach angle; rate of drift; orientation etc.
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Here is the same picture, but with more ambient light. The blue lights turn out to be standard FAA taxiway edge lights running at step 5, the brightest they can go. Despite this, the linear lights are still better! Both of these pictures were taken from the enclosed video.
Video: PANYNJ and FAA Linear Visual Aids Research, at the Downtown Manhattan Helipad
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At Night, With Linear Sources, Because Their Aspect Ratio Changes With Any Angle One Looks At Them, Their Linearity Effectively Restores One’s Lost Nighttime Depth Perception.
LEDline® safety and guidance at the Golden jubilee Hospital, 2012 Clydebank Glasgow, UK
The picture below is by Peter Simpson of
PSNK Aeronautical Services
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Video of LEDline® safety guidance lighting at the Golden Jubilee Hospital Helipad, Glasgow, Clydebank, UK
Linear visual aids provide much better visual cues for pilots at night, so improve nighttime helipad landing safety.
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USA helipad Copyright Bruce Lomesky
LEDline® Safety and Guidance Lighting at Kilmore Hospital Helipad, Australia:
Copyright Peter Simpson PSNK Aeronautical Services
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LEDline® Safety Guidance lighting at the Leongatha Hospital Helipad, Australia.
Copyright Peter Simpson PSNK Aeronautical Services
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VISUAL AID LINEARITY IS IMPORTANT ON AIRFIELDS since point source visual aids are confusing.
What are the lights below telling you?
With more light comes meaning. Note: The warning lights at the end of the picture, they are there to prevent people from driving ahead. Yet, with no pattern, context, depth or dimension to the point sources, drivers could easily think that they were still lining the road and could easily continue driving ahead and had an accident.
Again, with pictures that have been seen before; below are point source and linear source helipads at night and in daylight. With no visual cues, the point source helipad at night is highly confusing to everyone, including approaching pilots, unless they are looking down on the point sources. The helipad with linear visual aids is always from any viewing angle, crystal clear and there is no viewing confusion. In fact, with linear visual aids, one can not create nighttime visual aid confusion since no matter the viewing angle, the linear visual aids aspect changes and viewers automatically see the pattern, depth and dimension of the helipad.
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Therefore, at night, to be recognized and provide a meaningful dimension and depth to viewers, point source visual aids need to provide a pattern; without it, because of everyone's lost nighttime depth perception, the lights are confusing and have no meaning.
Linear visual aids always provide nighttime meaning, pattern, depth and dimension.