Differences between Stereoscopic 3D, Holographic 3D, and Hologram

If you usually visit this blog you may have wondered about the difference between 3D and other screen technologies. Here we’ll tell you the differences between them.

First of all clarify that this terms are not official (sometimes neither the manufacturers themselves are able to explain clearly what kind of image their products offer). But by publishing news and reading press releases and articles we have observed that the market has come naturally to this terms. So we can properly classify each product according to the type of image they produce.

Traditional 3D

First of all you have to understand how a traditional 3D screen works; 3D displays form the image from only two images, one for the left eye and one for the right eye. Regardless of the format in which it is recorded and the type of screen (active, passive, glasses-free, etc.) traditional 3D screens always display the same image angle regardless of the viewer’s position, if a viewer changes position he/she will still see the same angle of the image (or will lose 3D on glasses-free screens without eye tracking). As much as we deviate from the center the image will seem to stretch and deform to continue offering the same image angle. Also the amount of depth both inward and outward is proportional to the distance of the screen, by placing yourself farther away from the screen you are stretching the image, and if you move closer to the screen you are crushing it. This is because the brain receives the same information at both distances.

We can explain it with an example if we watch Beowulf‘s memorable scene in which the hero points the sword at our eyes. If we watch this scene close to the screen the brain will not have much trouble detecting the edge of the sword very close to the eyes, if we go very far from the screen the brain still sees that this sword is at the same distance from the eyes (that distance was fixed when recording the two points of view for each eye). Consequently, if in the image we see that the head of the protagonist is slightly inside the screen this will continue to be fulfilled whether we are near or far from the screen. If we are one meter (three feet) from the screen the sword and the arm will seem very short, however if we move several meters away from the screen the arm and the sword will seem excessively long.

Thanks to eye tracking you don’t lose 3D when you move, but the angle of the image remains the same and the image stretches or crushes while you move, just like with 3D with glasses (the animation does not accurately represent the perceived effect)

All this becomes much more complicated if we take into account the separation recorded for each scene and how this distance increases or decreases according to the size of the screen, then that is related to the fact that the eyes converge at different distances from the 3D image while in reality they are always focusing on the distance to the screen. All these factors combined can produce dizziness and discomfort if there is a lot of difference between focus and convergence, and depending on the size of the screen and our distance to it, and on top of that this varies for each scene. For these reasons, and besides differences in vision of each person, people can have different experiences with the 3D of the same film even being in the same cinema. If you are one of those who gets dizzy or uncomfortable with 3D while others enjoy it may be that according to the characteristics of your sight you are sitting too far or too close from the screen. And this has been a problem with 3D, which for some has seemed spectacular to others has been awful and even annoying.

If you are one of those who gets dizzy or uncomfortable with 3D while others enjoy it may be that according to the characteristics of your sight you are sitting too far or too close from the screen

3D devices examples (content recorded from a single point of view):


Holographic 3D screens

The main difference compared to a 3D screen is that as you change position you can see different angles of the image, as in reality. So it’s a more natural image and closer to seeing a real object in front of you, you can see the real volume of objects without any distortion even if you’re not in the center, and also allows people with spatial vision problems to appreciate depth of objects when moving. This solves all the criticisms from 3D detractors.

If you move or tilt the device you can see different angles of the image

Holographic 3D is a huge leap over normal 3D, since it doesn’t have the problems of traditional 3D.

Holographic 3D screens differ in the number of viewpoints they can display. The Red Hydrogen One Holographic 3D smartphone have 4 viewpoints (which can be generated from 5 virtual cameras). On the other hand, The Looking Glass holographic screen features an impressive number of 44 points of view (45 images), making it much more lifelike since you don’t notice jumps between one point of view and the next. It is not a written rule, but it seems that the market tends to name Holographic 3D to the screens with few points of view, and Holographic (but still not Hologram) to those that have such a quantity of points of view that when moving you don’t notice jumps between them. But even with few views the Holographic 3D devices are a big leap when compared to regular 3D, since it does not have the problems of traditional 3D.

Thanks to the calculation of depth maps all current 3D content can be viewed in Holographic 3D with different angles of image

There are 3D screens that, thanks to the combination of appropriate software and an infrared camera (limiting their use to a single person), become in fact Holographic 3D screens. Eye tracking alone does not automatically create a holographic display, specialized software is required that calculates at any time the perspective of the objects on the screen to modify the stereoscopic image as you move. Otherwise, eye tracking just deviates the center of the 3D image as the viewer moves, to keep the 3D effect. A New Nintendo 3DS is not 3D Holographic because the perspective is the same even if we move, but could easily become 3D Holographic if Nintendo designs the appropriate software, downloading a mere update there would be a revulsive so they could dramatically increase the sales of the console and particularly the games, because without the need to adapt them they would take on a new dimension – as graphics are rendered by the graphics card it can calculate the other points of view. An example of a 3D screen turned into a holographic screen thanks to the dedicated software was the Takee 1 smartphone, as it generated in real time a different image angle depending on the position of your eyes.

A New Nintendo 3DS could easily become 3D Holographic if Nintendo designs the appropriate software, downloading a mere update there would be a revulsive so they could dramatically increase the sales of the console and particularly the games, because without the need to adapt them they would take on a new dimension

3D Holographic screen examples:


Holograms

In previous articles we have emphasized that the dictionary definition of a Hologram are those 3D images that you can see from different angles on some postcards, on authenticity labels, and on some banknotes. However, despite repeating it many times we are aware that when you talk to someone about Holograms the first thing that comes to mind are the holograms from the movies. Holograms that are floating in the air without any screen. It’s so difficult to change that concept that it can be assumed dictionaries will have to change their definition sooner or later.

However, people are completely unrealistic and when we talk about holographic screens like the ones explained in the previous point they forget that holographic is not the same as hologram and they ignore the word “screen”, and instead of thinking about a screen they imagine things floating in the air. This is as absurd and unrealistic as if before the first films with stereophonic sound we wanted surround sound and above that, to be wireless. To achieve great innovations it is necessary to go through the intermediate steps, and if those intermediate steps are successful there is a greater chance that those great innovations will arrive sooner, but we cannot demand right now Holograms floating in the air without any type of screen or carry any device. To get there, not only does technology have to evolve, but content creators have to get used to work in 3 dimensions. If people obviate 3D and Virtual Reality, and on top of all the content is consumed in 2d, it is difficult to make a big jump from 2d to Holograms.

People are completely unrealistic and when we talk about holographic screens like the ones explained in the previous point they forget that holographic is not the same as hologram and they ignore the word “screen”, and instead of thinking about a screen they imagine things floating in the air

Today Holograms are possible… But with expensive glasses. And they will remain that way for a lot of years.

Fortunately there is a way to use Holograms today, but it would not be feasible without glasses as an intermediary. Just as sound could not be wireless since its invention, to see Holograms floating in the air without needing glasses will require more than a decade, at least. Holograms (or rather the glasses that generate them) also need to recognize the environment, something that still needs to be greatly improved, and generate computer content realistically in the real world. At the moment it is difficult to generate recorded content. If for Virtual Reality it is possible to record from a center everything that happens around with volumetric video, with Holograms it is necessary to record a central subject but from all possible angles, so that the spectators can move and see the objects from any angle. It is therefore better for the device to dynamically generate the content (or use CGI).

Many will say that instead of Holograms with glasses they should be called Augmented Reality glasses, but Augmented Reality was born crushed in 2d screens, in which it is necessary to use the hands to point the mobile to a place, with few possibilities of a comfortable interaction. That 2d interaction while holding the device is light years behind what can be done now with Magic Leap and HoloLens, in which you can interact effectively with the hands as you would with a hologram from the movies, therefore, to all intents and purposes, both in interaction and visualization, are Holograms.

There are also Hologram cubes, but besides being as expensive as glasses, the interaction capabilities and the size of their devices limit their potential uses.

We can use Holograms today thanks to Magic Leap and HoloLens (of which the second generation was just unveiled at MWC 2019). However, its implementation and content is still limited because, as we have said, we are mostly in a 2d world and it is a very big paradigm shift to generate 3D content while allowing total freedom in visualization (we are not even talking about adding interaction from any angle). One of the reasons for the slow adoption of Holograms is because there are few sources of 3D creators, and the main one is Virtual Reality, which does not have the massive success expected (which we expected due to those helmets that force you to isolate yourself from the world and need a preparation/verification of the environment before putting on the helmet).

If Holographic screens are successful – they are already cheaper and more user friendly than Holograms – more creators will be able to work faster by looking at their designs in real time as they create them and make more content and develop more practical applications in less time, without the investment that has to be made to use Holograms.

Although they are exciting the price is too high, a transition from 3D Holographic screens would lower the cost and also ensure its success as there will be many creators and developers.

In addition there is the fact that currently most creators design those contents on their 2d screens…. So they have to spend even more time working with perspectives and constantly rotating their designs to envision how it will look in 3D before testing the result. Fortunately,
If Holographic screens are successful – they are already cheaper and more user friendly than Holograms – more creators will be able to work faster by looking at their designs in real time as they create them and make more content and develop more practical applications in less time, without the investment that has to be made to use Holograms. In addition, with consumers in mind, Holographic screens can be used on a massive scale right now, whereas Holograms cannot be used until the technology is much less cumbersome, which means there is a lot of potential market for Holographic screens before Holograms are massive, and that content and experience will benefit when Holograms will become mainstream.

That’s why both Red Hydrogen One and The Looking Glass have targeted the creators community rather than the mass market. Thanks to these devices creators can start making holographic content for these screens, and as they gain experience and discover what works and what doesn’t, the Holographic 3D screen market can succeed and prepare both consumers and creators for a future in which Holograms can be mainstream.

Hologram product examples:

HoloLens and Magic Leap

Cubes with pyramidal screen

Ooh!

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