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Hologram, which technology to choose ?


The hologram makes you dream and when it appears, the wow effect is guaranteed. This is why we are seeing more and more use of holograms in the field of art, but also in marketing, communication, conferences, etc.


As we have seen in our previous articles, there are different processes and devices to create an extremely realistic hologram. It is useful to specify here that it is indeed holographic simulation which we are speaking of, and not of real holograms, as the technology to do so is not yet mastered. (check out our article about this).



Here is a detailed summary of the available processes, with the advantages and disadvantages of each, as well as the types of uses for which they are most suitable.



Holographic helixes


Principle


Hundreds of LEDs are placed on the branches of a propeller, the rotation of the propeller and the color changes of the LEDs create an image. The speed of rotation of the propeller makes it invisible to the human eye, so it looks like the image is floating in the air. (more about how the holigraphic helixes work).



Advantages

  • Light logistics: the propellers are light and easy to transport, they are fixed on a vertical wall or a wall with standard screws. Some models can be parked simply when they are in their protective case, indeed for some models the acrylic protective case is square and can be put down on the floor directly, on a table or any shelf.

Helipix D100 in its square protective case that can be placed on the floor
  • Brightness: the helices are directly the emitting source of the image, it is thus very sharp and can thus they can be used in almost all the conditions of luminosity, contrary to the projective processes where the images are more faded because projected on a surface.


Disadvantages

  • Size of the hologram: the largest propeller model is 1 meter in diameter and of course the images must fit into a circle of the diameter of the propeller. It is therefore not possible, for example, to make a person appear on the same level in real size.


  • Noise: the rotation speed generates a certain amount of noise which is estimated at more or less 30 db depending on the model. This noise level will have absolutely no impact in a noisy environment such as a trade show, but can be a little more disturbing in a quiet environment. However, it should be noted that when a propeller is placed in its protective shell, the noise level is much lower and equal to 0 db at 5 meters from the propeller.


  • Safety: the device itself is not dangerous, but in an environment where there is a public, it is essential to make sure that people do not try to touch the propeller while it is working. The process is always amazing to the uninitiated, and people may be tempted to try to put their hand through the image to see what is going on. The curious will get away with a sore hand at most, but the device itself may be seriously damaged. The propeller must therefore be secured or fitted with its protective shell, which is mainly intended for this purpose.



Ideal for


Holographic helixes are ideal for the following uses:


  • In-store signage.

  • Display animations.

  • Attracting and surprising at a trade show.

  • Create an avant-garde design in bars, clubs, restaurants.



A wall of combined propellers


Principle


It is the synchronization of several holographic helixes placed side by side to form a much larger image. The process is exactly the same as for LED tiles that are assembled together to form a giant screen of the size and shape you want. The helices connected in this way are recognized and the interface then considers them as a single device to which it will adapt in terms of size and resolution.



Wall of 9 helixes X65 synchronized to form a holographic image of 155*155 cm

Technical diagram of the assembly of a 9 Helipix X65 wall

We note on the diagram that the helices overlap to create a continuous image without "holes". Indeed, since they are circles, it is not possible to simply put them side by side like square LED tiles. The spacing is very precise, as is the height difference so that the helixes do not touch each other while rotating, while maintaining a solid image. The supplied bracket already has all the slots, so all you have to do is attach the propellers to it. The brackets are made to measure according to the number of propellers required. However, it is possible to do without them simply by scrupulously respecting the assembly diagram.



Advantages

  • Size: this process allows you to have no size limit for your holographic image. The size will only depend on the number of helices you synchronize together.

Here a synchronization of 4 helipix D65H propellers


  • Brightness: As well as the propellers alone, the wall is the source of the image


  • Spectacular effect: from a certain number of helices synchronized between them the effect becomes really impressive. We find ourselves in front of a giant hologram that we have the impression of being able to walk through (something to be avoided of course :))

Here is a wall of 40 synchronized Helipix D65H propellers



Disadvantages


  • Price: depending on the size you want, the budget can become significant, so it must be considered at the beginning of the project. This is often the starting point to project a given size for your propeller wall.


  • Heavier logistics: when you buy a holographic helix there is very little to do to put it into operation. For a wall it is more complex, first you have to mount the propellers and then fix them to the support, manage the power cables etc. The larger the installation, the more likely it is that a technician will be needed. In the case of a rental, it is of course not possible to send the wall by carrier, it is thus necessary that a person comes to assemble it on the site of the event, which generates a logistic overcost.


  • Noise: it must be taken into account, the combined rotation of all the propellers generates a noise. It will be quite acceptable in a noisy environment such as a living room but not in a place that would require silence.


  • Safety: in this configuration, protective cases are not possible because they would prevent the overlapping of the propellers. It is therefore essential to prevent access to the wall and to provide a safety zone in front of it.




Ideal for


A holographic helix wall is ideal for the following uses:


  • Large display animations.

  • Attract and surprise at a trade show if you have a large booth.

  • Create an avant-garde design and convey information in establishments such as bars, clubs, restaurants.



Holographic displays


Principle


A screen hidden in the top of the display projects an image onto the sloping walls of the display. Because of the studied inclination and the coating of the walls of the display, the reflection of the image appears in a very clear way in the center of this one and gives the perfect illusion to float in the middle of the display. There are several types of displays that can be classified according to the viewing angle they offer, namely 180° (one side); 270° (3 sides) and 360° (4 sides). (Learn more about how holographic displays work). Each type of display comes in different sizes to be chosen according to the use for which it is intended. (View all existing sizes)

From left to right: holopix display 180°; holopix display 270°; holopix display 360

The holographic display can be used to create an animation around a physical object or to make an object appear in hologram in a completely virtual way.



Advantages

  • The classy side: the finishes of the holographic displays and the materials used (glass and metal) make it a premium object that indisputably enhances the product that is inside, whether it is really present in the display or only in the form of a hologram. Moreover, the interaction between a physical object and a holographic animation brings a real plus that really makes the difference.


  • Lightweight logistics for small models: up to 32" holographic displays are easy to move and can be placed on suitable furniture or any other suitable place at eye level.


  • Easy to use: Just plug a USB key containing your video file into the back of the display, turn it on and off you go, the animation starts. No complex settings are required, a simple remote control allows you to manage the basic functions.



Disadvantages

  • Size: the holographic image created by the displays is relatively small. The displays are therefore well adapted to the enhancement of products with high added value, a logo for example will be much less effective than on a propeller and the range will also be less important.


  • Heavy logistics for large models: if you want to obtain a larger image or enhance a relatively large product such as a magnum of champagne, for example, you will have to opt for a large holographic display, i.e. from 42" (see the dimensions of the displays according to the size in inches). In this case the logistics become heavier, these displays can not be handled by one person and the transport becomes delicate because the glass walls give them a certain fragility against shocks.



Ideal for


Holographic displays are ideal for the following uses:

  • Showcasing premium products (jewelry, watches, high tech, perfumes ...).

  • Display animations.

  • Animating your booth at a trade show if you present products that can be highlighted with holographic displays.

  • The presentation of some of your products at the point of sale.


Rear projection on holographic film


Principle


It is a question of retro-projecting an image on a transparent surface covered with a holographic film. This holographic film is also quasi transparent. It will have been applied beforehand to the back of the surface (retail outlet for example) and a video projector will send its beam directly on the film, it must thus also be placed behind the display. The diagram of the process is as follows:

The video projector can be placed on the floor, on the ceiling or horizontally in relation to the projection surface. It is however necessary to take care not to dazzle the spectator with its beam and to pay attention to the residual images which cross the surface. The image thus obtained remains transparent and gives the illusion of the hologram. It is however important to work correctly the file beforehand to optimize the result. (view an example of the application of this process).



Avdantages


  • Light logistics: the holographic film is easily placed on any transparent flat surface (glass, Plexiglas). It is then enough to place the video projector at the good distance to have a very impactful result. Here the hologram effect is essentially due to the transparency of the image. (see the technique to install holographic film). For an event application one can for example very easily implant a plate of Plexiglas of 200*100 cm and a projector to create a character with human size almost anywhere.


  • Size: due to the range of professional video projectors available on the market, it is possible to obtain relatively large images. We can then easily imagine human-sized characters moving on a space like a stage for example.

It should be noted here that the size of the image requires two synchronous projectors and significant work to produce the video file.



Disadvantages


  • Brightness: the surface on which the image appears is not the source of the image, and its transparency, which is essential for generating the hologram effect, causes significant loss of brightness. It is thus necessary to be attentive to the external conditions of the installation. If there is too much ambient light, the image may be too blurred and not very visible. A nocturnal or dark environment is ideal for the use of this process.


  • Residual image and technical constraints: As seen in the video above, a residual image appears on the sidewalk in front of the dealership. Here the projectors are fixed to the ceiling, we can see the two luminous points of the beams. the residual image is not disturbing in itself if it is well managed. an installation of the projectors on the ground would have made it disappear but would have prevented to have elements in the display because they would have cut the beam. There are therefore technical constraints to be considered before setting up a project, which requires a precise study. In the case of an event installation it will be necessary to consider the necessary distance between the projector and the plate (approximately 3 meters for a hologram with human size) and to secure the zone located between the projector and the surface of projection so that nobody comes to cut the beam.



Ideal for


Overhead projection on holographic film is ideal for the following uses:


  • Animations of large displays.

  • The creation of a human-sized hologram, especially for events or for permanent installation.

  • The animation of conferences.

  • The creation of holograms for shows.



The Pepper ghost



Principle


The Pepper ghost is an old technique invented in the 19th century by Henri Pepper and which was used in the theater to create the effect of a ghost. It consists of using the reflection of an actor placed against the stage, in a tilted glass. The image thus obtained seems to be offset from the glass. The principle is similar to that of the holographic displays. Here is an illustration of the Pepper ghost as it was used at the time.

Of course today the processes have evolved enormously and the "actor" no longer needs to be present, a projector diffuses an image on a mirror placed on the ground and it is this image that is reflected by the surface. This is how it is possible to make deceased artists "come back to life" or to make a person appear in two different places at the same time.

Tupac concert in hologram thanks to the Pepper ghost process


Advantages


  • Size: the Pepper ghost allows you to create very large holograms or holograms that can move on a large surface such as a festival stage for example. You just have to adapt the reflective surface and the mirror, as well as the number of projectors, and there is actually no limit to the possible projection surface.


  • Interactivity: as we can see on the diagram above with Tupac and Snoop Dog, the inclination of the surface allows a person or physical elements to be present on stage at the same time as the hologram, it is thus possible to create an interactivity between the real and the virtual for an even more impressive effect.


  • No residual image: since the projection is made on a mirror that is reflected in turn on the surface of the Pepper ghost, there is no residual image. Moreover, if the lighting conditions are worked in an adequate way, the Pepper ghost becomes totally invisible to the eye of the spectator, contrary to the rear projection technique where the projection surface always remains slightly apparent and where the residual image is present. The effect becomes really bluffing and the spectator who does not know the technique cannot guess the functioning of the process.



Disadvantages


  • Heavy logistics: the logistics are complex, first of all you have to consider the reflective surface, even if it exists in the form of a film that can be stretched, easier to handle than a rigid surface, it is nevertheless necessary to foresee all that is necessary to fix it without it being able to relax, to work carefully on the general lighting so that it remains as invisible as possible and to secure it so that eventual physical interveners or even the public do not come into contact with it. Then you have to take into account the mirror which has to cover the whole surface, so depending on how big and heavy it is, you also have to make sure that it is invisible to the public, so you have to set it up in particular stage conditions, with a sill for example. Finally, you need powerful projectors, therefore heavy and expensive, and you need to be able to synchronize them. As you can see, this process cannot be improvised and there are companies specialized in its installation.



Ideal for


The Pepper ghost technique is ideal for the following uses:


  • Performing arts



Holo-gauze.


Principle


The holo-gauze or holographic fabric is a flexible reflecting surface which is in the form of a veil covered with a very reflecting metallic coating. It captures the images diffused by a video projector in direct or rear projection. The transparency of the holo-gauze is such that, under the right lighting conditions, it becomes almost invisible to the human eye and the image it reflects seems to float in the air. Moreover this image keeps a transparent aspect which gives much more power to the hologram effect. The process is very close to that of the overhead projection on holographic film but it can be in certain cases easier to set up.

What holo gauze looks like

The different layout possibilities with the holo-gauze

Want to know more about holo-gauze? We have written a very detailed article on the subject from which this latest diagram is derived, read it here.


Advantages


  • Easy handling and installation: here there is no need for a heavy rigid surface to carry, the holo-gauze folds and unfolds like a tarpaulin, so it is very light and easy to carry. To install it, all you need is a suitable frame in terms of size to which you can attach it with its eyelets. Its leather surround ensures its integrity.


  • Size: the holo-gauze can be manufactured in one piece for a surface of 15*30 m, it is thus possible to create a disproportionate hologram, it is besides what made Eric Prydz at the time of his show HOLO with the largest hologram ever created on a scene (20*5m). attention however in this case the projectors used were ultra powerful and the show in itself required an impressive logistics

  • Projection direction: unlike rear projection on holographic film, the holo-gauze is able to reflect an image in an optimal way whether it is projected from the front or from the back, which gives more options, particularly as regards the management of the residual image.



Disadvantages


  • Brightness: holo-gauze requires a high power projector (7000 lumens minimum) for an effective result and a rather low ambient light level. For example, the projectors used for the Eric Prydz show have a power of 30,000 lumens and the room is plunged into darkness.


  • Fragility: the holo-gauze is made of very small honeycomb meshes that allow it to remain very transparent, but this makes it fragile, so it is essential to avoid people touching it, otherwise it will tear. It should also be stored carefully.

  • Residual image: as with rear projection, the surface of the holo-gauze, because of its transparency, captures the image of the projector but also lets a good part of it pass through. As a result, a residual image appears behind it and it will be necessary to study the implantation carefully so that it does not distort the hologram effect.


Ideal for


The holo-gauze projection is ideal for the following uses:

  • Performing arts.

  • Event animation.



Conclusion


All holographic simulation techniques have their advantages and disadvantages, but you will always find the most suitable for the creation of your hologram in the particular context that is yours. The list of the techniques available to date is exhaustive but will certainly be likely to evolve quickly because holography is a young technology and in full evolution and the fast progress which is currently made in the field of the image (appearance of the flexible screens in 2018 for example) let foresee many innovations very soon.


Here, we have presented the ideal situations in which these various techniques should be used in order to help you choose the best one for your project but you can of course imagine any other use that would not have been mentioned here and adapt any of these techniques if the environment allows it. At Holopix we are listening to you, don't hesitate to present us your project and your desires and we will advise you the best way to implement them.



Benoit DEROT



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