Misleading Terms
This section will cover some brief notes on frequently misleading terms used to market various displays. Here are a few:
3D LED Displays and Forced Perspective
Holograms
It should be mentioned that none of the displays mentioned in other sections are in line with the definition of a hologram. A hologram is closer to a photographic medium as it captures an imprint of the light waves that bounce off an object. Most of the media headlines these days with the word “hologram” are typically talking about simple optical tricks or AR. Holograms have taken on a cultural meaning that differs from the scientific definition, similar to the cultural rebranding of “synesthesia” or “literally.” This article by Oliver Reylos has a concise summary of what is considered holographic and what isn’t. In his words:
When viewing close-by objects, there are six major depth cues that help us perceive three dimensions:
Perspective foreshortening: farther away objects appear smaller
Occlusion: nearer objects hide farther objects
Binocular parallax / stereopsis: left and right eyes see different views of the same objects
Monocular (motion) parallax: objects shift depending on how far away they are when head is moved
Convergence: eyes cross when focusing on close objects
Accommodation: eyes’ lenses change focus depending on objects’ distances
Almost all of the displays or techniques in this article have some holographic properties like parallax or multiple viewing angles, but are primarily in a class of their own. Would you call an oil painting a sculpture?
Autostereoscopic Displays/3D TV's
3D TV's are primarily a marketing term for something that is more accurately called an autostereoscopic display. These TV's aren't pushed as much in 2022 because they never really caught on for most of the public, primarily because they overpromised the 3D effect.
More on various types of 3D Televisions.
LED TV's
This term has been mixed up for a while and is more accurately known as an LED-Backlit TV.
LED's as a light source were an important development for backlit LCD's many years ago and allowed the creation of thinner and more energy efficient LCD displays of the traditional CCFL (Cold Cathode Flourescent Light) light source. Unfortunately the marketing term causes them to be mixed up with LED video displays which use a very different approach for creating light. There are more and more displays and TV's that are starting to use things like microLED technology that will eventually make this even more confusing, but for now you can usually assume that an LED TV or monitor is usually only referring to the backlight.
3D LED Displays and Forced Perspective
There have been more and more of these kinds of videos popping up on social media in the last few years. While this isn't necessarily a misleading term, the way they are presented in a video setting is misleading to how they are percieved in real life.
Light Field Labs has a breakdown where they explain this phenomenon fairly well:
There has been a great deal of hype in recent years around the use of various optical illusions such as forced perspective or anamorphosis that make content on large format displays appear three dimensional—in particular using installations that wrap around the building like that at 20 Times Square. The advantage of the wrap-around design is that content can be used to create the impression that the screen is a large cube that has been cut out of the building. Action can then take place on this “stage” area that appears to extend back into the structure. If the stage area is smaller than the screen, objects can be made to appear as though they are moving out of the display.
In the first example below, the far end of the digital display is darkened so it looks like part of the building. When the hand passes into this part of the screen it looks as if there is building frontage behind it, tricking the viewer into thinking it must have reached out beyond the dimensions of the display. The illusion is spectacular when viewed from the right angle, but breaks down when the viewer moves to a different vantage point.
And here is a video that kind of debunks what these displays look like when moving around them in an actual city setting:
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