Comparing Innerscene Virtual Sun with LED Panel artificial skylight panels

A number of companies offer artificial skylight that use a simple technology based on LED backlighting and a silk-screen transparent image as shown above.

This type of product goes by various different names, including:

• LED Sky Panel / LED Light Windows / LED Glass Windows
• LED Sky Ceiling
• Fake Window / Artificial Window / Virtual Window
• Fake Skylight / Artificial Skylight / Virtual Skylight
• Electric Skylight
• LED Glass Window / LED Panel Window
• Sky Roof Light / Box Skylight

These products are sold numerous companies including:

• Sky Factory (https://skyfactory.com)
• Artificial Sky (https://artificialsky.com)

Traditional sky LED panels combine a backlit light source with a silk-screen printed image to produce that same effect seen when looking at a lighted advertisement at a bus stop of a movie poster. While such products can look visually correct in a photograph limited to a single camera viewpoint, they do not provide a believable sky view in real life for reasons discussed below. Because the image being back-lit is 2 dimensional in nature, in real life our two eyes quickly perceive it for what it is - a flat backlit image on your ceiling. In more advanced versions of LED panel products, a LCD screen is used to allow for dynamic images - however this suffers the same problems of looking flat and having poor light quality. A few of the reasons these panels do not fool our brains into thinking we are looking outdoors into the real sky are listed below.

One of the most important things a window or skylight provides us with is views to the outdoors and a sense that we are not confined to a windowless room.

The LEED design standard for architects requires 75% of all regularly occupied floor area have “views that include at least two of the following: (1) flora, fauna, or sky; (2) movement; and (3) objects at least 25 feet from the exterior of the glazing”.

Traditional LED Panels do not support depth cues used by our eyes and brain to determine how far away something is from us.

Motion Parallax Cue

When we move our head left to right and forward and backward, objects that are located at infinity appear to move with us. Objects that are close to us will move in the opposite direction of our head. With the smallest of head movements, a casual observer would perceive an LED panel as a flat image located on the ceiling. In contrast, Virtual Sun provides perfect motion parallax cues - when you look at the sun and move your head, the sun will perfectly track your head movements as if it was a million miles away.

In the animation above, note that objects closer to the camera appear to move faster than objects in the background. Because the sun is millions of miles away, it stays fixed in the sky and appears to travel with us.

Stereopsis Cue

Our brains process images received from the left and right eye to estimate depth. Objects that are far away from us will be seen as the same image by both the left and right eye, objects that are close to us will have differences that allows the brain to calculate the distance between us and the object. You can try this by closing one eye at a time and seeing how near and far objects appear. When LED panel manufacturers advertise their products online, they are only presenting a single motion-less camera view of the product, so the lack of 3D isn’t as apparent. When LED panel manufacturers show the panels in videos, they typically use only tilt & zoom where the problem of Motion Parallax Cue can be hidden from you. In contrast, Virtual Sun presents the same image of the sun and sky to your left & right eye making it appear as if the sun & sky are millions of miles away.

Our left and right eyes see fairly different images as shown below. Our brain processes the differences between these images to determine how far objects are from us. When there are great differences for a point, it is perceived to be close to us. As an object approaches infinity, the left and right eyes will see exactly the same thing and our brain signals to us that the object is very far away. Virtual Sun shows an image of the sun that is the same to our left and right eyes using a unique new technology patented by Innerscene.

Accommodation Cue

Your brain controls muscles in your eye to change the focus when looking at close objects (<2m) and far objects. When looking at a Traditional LED panel from a distance of less than 2m (which is typical), our brain will adjust our eye focus to accommodate a nearby object which instantly tells us the object is not far away from us. In contrast, Virtual Sun is actually presenting the sun and sky at optical infinity so our brain will focus our eyes far away when looking “through” the fixture. Your mobile phone camera does the same thing. When taking a picture of the Virtual Sun, your camera will change it’s focus to accommodate distant objects no matter how close you are to a Virtual Sun unit.

For more depth cues that are used by your brain to determine how far away an object is from you, see:
http://www.hitl.washington.edu/projects/knowledge_base/virtual-worlds/EVE/III.A.1.c.DepthCues.html

CRI (Color Rendering Index)

Traditional LED Panels start with a high CRI LED light source, but when this light passes through the silk-screen various parts of the light spectrum are absorbed causing the resulting light emitted from the device to have a poor CRI (less than 90, often even lower than 80). Typically, in order to create a blue sky, these devices start with white light that passes through a silk-screen which absorbs most of the non-blue spectrum resulting in light that has very little red and green light. The result of low CRI is that the perceived colors in nearby objects will suffer, for example people’s faces will look unnatural and the colors of floor, wall, furniture, and decor will look “off”. Contrast this with Virtual Sun which combines light spectrum for a wide range of LEDs to achieve a CRI over 90 over a wide range of CCTs.

Light distribution

LED and LCD panels only produce diffuse light which sends light in all directions, but do not have any directional “collimated” light. A room light by natural light will typically have both components at various times of the day. Virtual Sun can be thought of as 2 light fixtures in 1; there is a diffuse sky component that emits light in a 180 degree beam similar to traditional LED panels, but what makes it special is the sunbeam which emits a 2.5 degree angle beam that will light up your floor or wall to further create the illusion of real sunlight coming into a room.

Dynamic CCT

Traditional LED panels can typically only emit one CCT, 6500K being the most common. However, there are many reasons why a color tunable product is preferred:

Light from the real sky changes constantly throughout the day. Virtual Sun’s Circadian Rhythm mode does exactly this. Rooms with static CCTs can feel monotonous and claustrophobic because there is no change all day long.

Research studies show that Circadian Rhythm Lighting can lead to:

• Faster cognitive processing
• Increased alertness in the morning
• Improved mood, productivity, and concentration
• Improved sleep
• Reduced hyperactivity
• Reduction in errors and accidents

For more information on this topic, see this article.

The image below shows the appearance of Virtual Sun at a few different times of day and night. The changes occur slowly over the course of a 24 hour period.