# Pepper's Ghost / Projection surface ?



## afvda

I've seen a few posts on this forum proposing variations to Pepper's Ghost, I am hoping someone might have some advice for me.

I'm looking to implement the technique in an art installation, the space I have to work with is about 4 x 3 m and has a curved/dome like walls & ceiling,
I plan to adapt the construction of an enclosed structure to best accommodate the particularities of the space (namely its curve) the positioning of the various elements required for the technique, and to minimize the size of the angled 'glass' surface that captures the reflection that the viewer sees.

I have scoured the net for all info I can find regarding this angled 'glass' surface, the various solutions people have used ranging from a low-budget plexi-glass solution, to Eyeliner's patented setup & holo-foil,
Budget-wise I would be happy on settling for something inbetween these two , my own tests with plexi-glass haven't given very effective results - with the audience at close proximity, effectively 'hiding' the edges of plexiglass does not seem very possible.
A very thin surface seems more desirable so I have been trying to find out what the "Eyeliner foil" actually is, since it is patented it is only ever referred to as that. Certain clues in their patent led me to Beam splitter coatings and this company that mentions Pepper's Ghost in relation to their product : Thin Metal Films LTD - Beam Splitter Coatings
I am currently waiting to hear back from them, but I have a feeling the price for a 1 x 1.5 m glass will be out of my budget.

I have seen talk of :
- window film (which to me does not seem like it could work because of the tinting ?) Are there any other products, domestic or otherwise that have the same properties as a Beam splitter coating (being transparent and anti-reflective) ?
- teleprompter glass / half-silvered mirror - I'm not sure how this could work ?

The best projecter position to me seems to be the setup Eyeliner uses, so I'm considering this arrangement : *Google Image Result for http://cdn.uproxx.com/wp-content/uploads/2012/04/tupac-hologram-diagram.jpg*
As well as the traditional "L" shaped spatial configuration : *http://tinyurl.com/bl48rtp*
I have considered rear-projecting, but hot-spots seem unavoidable (am i wrong?) and all the 'transparent' rear projection screens I have seen (sometimes advertised as 'holo-screen') are not actually transparent, but a very light grey colour.

Any leads are welcome !


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## Curator

Hi... I'm a curator and currently trying to do the same thing in an art installation in San Francisco. I did find this company that has similar foil systems to Musion Eyeliner in New Orleans. They are license free and don't charge each time it is used. Of course, I don't know the cost.

Arena3D Industrial Illusion Holographic Projection - Arena3D Industrial Illusion Holographic Projection

If you find an alternative solution, please post it. Thanks and good luck with your art installation.


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## afvda

Curator said:


> Hi... I'm a curator and currently trying to do the same thing in an art installation in San Francisco. I did find this company that has similar foil systems to Musion Eyeliner in New Orleans. They are license free and don't charge each time it is used. Of course, I don't know the cost.
> 
> Arena3D Industrial Illusion Holographic Projection - Arena3D Industrial Illusion Holographic Projection
> 
> If you find an alternative solution, please post it. Thanks and good luck with your art installation.




Hi there,

Thanks for posting, it’s nice to come across someone on the same path,
I cannot yet confirm an alternate solution, I am still in the process of gathering samples of different products to test, 
I have also asked someone I know who has an honors degree in chemistry to take a look at the patent, I will post what I discover.

Here are the commercial products I have found so far, that seemed promising enough to get hold of a sample: 

In a speciality plastics shop in Paris (WEBER Metaux et Plastiques) I found sheets of “polycarbonate”, it is ultra-transparent and has a 1mm thickness. From what I can see so far it yields a much crisper reflection than acrylic and is similarly inexpensive (I was quoted around 50EU for a 2 x 1.5 m sheet) I suppose it does not have any anti-reflection coating, but its thinness and at the same time rigidity (that would aid in minimizing image distortion) I find appealing at this stage.

This company have sent me a free sample of their “Glassless mirror”, product code #4651 0225 (Giant Mirror - Showtex NV)
I was quoted around 125EU for 1m x 1m. It is a thin, transparent, flexible, film, they also sell tension frames. The technical properties of “100% PES” seems to be derivative of polycarbonate, with flame-retardant properties (Polysulfone - Wikipedia, the free encyclopedia). In the company’s list of projects it looks like this product has been used to produce a Pepper’s Ghost type illusion, but again I’m not yet sure of its anti-reflection properties.

This company (Thin Metal Films LTD - Products) are sending me a sample of their ‘beam-splitter glass’ (30EU to cover the postage from the UK to France). This seems to have the same technical properties as Musion’s film – but unfortunately they only manufacture it as a glass. I was quoted around 525EU for 1m x 1m.

I did come across Arena3D, it does seem promising - but I remember seeing a pricelist (afraid I can’t remember where) and thinking it was over my budget. If it’s not over yours, they might be worth contacting at least for a quote ? I have a vague recollection of around 2,000EU for the film, this may or may not be grossly inaccurate.

I am curious to hear more about your installation, however l understand if you do not wish to share this publicly,

Best wishes,


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## Curator

Hi...

Thanks for your reply.

Based on your research, it seems like the polycarbonate sheets are the most economical. I too question their anti-reflective properties. And, I would like to avoid using glass, if at all possible.

I think I'm going to contact Arena3D and get a quote on the film. If your estimate is correct, then it will be too costly for the installation.

I have to believe that there is an alternate solution. I'm going to keep researching other options.

Regarding the art installation I am working on, in an effort to protect the integrity of the artist's work, I do not wish to share in a public forum. I see that you understand.

I'll post any findings I come across. 

Best wishes,


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## ruinexplorer

When I was speaking with Jake Pinholster at Arizona State University, he had mentioned that they used several different materials to achieve this effect that were more economical. I will drop him a line and see if he has any more specifics (or see if I can convince him to come here to discuss it himself).


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## afvda

Curator said:


> I have to believe that there is an alternate solution. I'm going to keep researching other options.



I totally agree that an alternative must exist, I do not plan on giving up any time soon either
It seems to me that the key to finding this alternative may be located in the patent, if one could only understand the language ... 

Thanks for your input *ruinexplorer *- it would be really great if you could get hold of Jake, any information or advice will be appreciated.

In the meantime, on a related note - I am considering buying the Optoma EW762 to use in implementing the technique, would anyone have any strong objections to this projector ? or want to suggest an alternative ?
Have you decided upon which projector you will be using *Curator *?

Best wishes,


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## jakepin

afvda said:


> I totally agree that an alternative must exist, I do not plan on giving up any time soon either
> It seems to me that the key to finding this alternative may be located in the patent, if one could only understand the language ...
> 
> Thanks for your input *ruinexplorer *- it would be really great if you could get hold of Jake, any information or advice will be appreciated.



Hi, all. I'm Jake. 

We have had success with a number of different materials for this effect. For the installations being discussed here, I would recommend a commercial window glazing film. Preferably, either a transparent "UV Block" version (completely transparent to the visible spectrum) or a slightly silvered variety (like the 70 Slate option at this link). We buy ours from the company at the link (AZ Solar Control), but there may be closer sources to you. The material comes in widths of up to 6-10ft, depending on manufacturer and variety. The anti-reflective properties are good, but it is still imperative to make sure that the audience side of the film is darker than the image and the stage side - Pepper's Ghost will work with any glass/transparent material if this can be achieved perfectly. It is less than 1mm thick and flexible, but relatively easy to hold taut without deformation (which is really the core of the Eyeliner product, not the film itself: holding a sheet of transparent film perfectly taut over a long distance without deformation). Last time we purchased, it was around US$20 per linear foot for a 6ft roll.

A few other responses:

- afvda, regarding your potential setups: remember that the illusion depends on the projected surface not being visible to the viewer, so unless you have the ability to create a recess in the floor or a "corral" to surround the horizontal screen, then the Tupac version probably won't work in the room you are describing, as far as I understand it. The "L-shape" setup is probably more feasible.

- Also, regarding Optoma projectors: stay away. Optomas, in my experience, have poor color rendering, a tendency to over heat, develop green lines and white edges frequently, and in general have a short life span. If you are looking for an economical projector in a similar range with similar properties, try an InFocus instead.


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## metti

I would also look at NEC units in that spec/price bracket. I have had a lot of success with NECs in pretty demanding applications and I know of smaller NEC projectors that are out on major tours.


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## afvda

Thanks for the tips Matthew & Jake, I'll have a look into NEC & Infocus projectors,
I realize it varies alot between models/brands, and that it might not be possible to reccommend without knowing the particularities of the environment this installation will be in - but in your experience is there a minimum contrast ratio & lumen count that you would not reccommend going beneath ? in the context of Pepper's ghost.

Jake, just a question about your projection setup suggestions - I have a configuration in mind for my setup that would allow the projection source & projected surface (the floor) in a Musion-type-setup to be hidden from the viewer's line of sight, it seems to work in theory but in the event that it doesn't in practice I will fall back to the L-shape,
In your experience with the L-shape setup (or any other setup you have used) - have you projected directly onto this window film ? Or have you bounced off a mirror or another surface first ?

Thanks in advance


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## ruinexplorer

Since the stage is often elevated as would be the exhibit, what about a more classic approach? If the projector were directly below the surface with an angled screen, it might be possible to use less space in front and be less likely to be seen by the audience. Similar to the photo below, but instead of the performer, replace with the screen.


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## jakepin

ruinexplorer said:


> Since the stage is often elevated as would be the exhibit, what about a more classic approach? If the projector were directly below the surface with an angled screen, it might be possible to use less space in front and be less likely to be seen by the audience. Similar to the photo below, but instead of the performer, replace with the screen.



For Pepper's Ghost to work, the angle of incidence of the audience sightline must be roughly equal to the angle between projected surface and reflection surface/film. _You cannot project onto the surface of the film/glass/mirror itself. _ The principle is akin to being lit in a room at night and trying to look out the window, where the interior lit objects and the streetlights (or whatever) beyond are "composited" into one image: the brighter object/projected image is reflected in the transparent window, with the lit objects behind the glass also showing through. 

In the "L" setup, you must project (rear or front) on a surface just offstage.

You could use the projector-under-the-stage setup, but you would need a mirror in order to get the image flat on the floor. 

(Incredibly rough) sketch of some of these ideas:


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## ruinexplorer

I guess what I was thinking (which would require a bit of experimentation) is that the floor projection surface would actually be angled, which would of course affect the angle of the film (more vertical) to properly reflect towards the audience. The question for me is if there is an angle of the film where the effect is lost due to glare or something else?


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## jakepin

ruinexplorer said:


> The question for me is if there is an angle of the film where the effect is lost due to glare or something else?



Some films or surfaces might have optical qualities where extreme angles result in different chromatic or spectral effects (some thicknesses and refractive indexes may cause light to bounce off both the first surface and the second surface, creating rainbow edges or blurry images), but the main problem is making sure angle of incidence (position of the image relative to the surface) equals angle of reflection (line of sight to the audience). You could tilt the surface forward and the image back to maintain this angle, but then you get to a point where you need a huge chasm underneath the stage.


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## rodrigo

Hi all, I am in search of technology as some of you and I found it interesting the Anti Vandal Window Film from any company for its performance and stiffness to slack and eliminate distortions in the image. These materials generally have a glue on the inside but I'm to eliminate it with solvents that do not affect the projection area. the union of these cloths or any polymer is made by welding methods to achieve higher hypersonic sizes. From Argentina. Rodrigo H.
Greetings to all


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## micrem73

Hi @afvda ,
What did you choose at the end? I'm in search of a pepper ghost cheap film too and wish to know which result your recent search gave you.
regards

michele


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## Rodrigo Hernandez

My dear colleagues, the name of the polymer is Mylar, invented it in 1950 Dupont, is the same as used Musion, just look at the micron, I think they are 100. Greetings and success for everyone from Argentina the most beautiful country of Latin America


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