Pepper's ghost is a fun illusion that allows you to create a ghostly image in the middle of a room that you can see the room around, or in this case, on top of a smartphone as if the phone were projecting a hologram. A video of it in action along with step-by-step instructions for making one to fit your phone is below.
As is illustrated below, the image is displayed on the smartphone and is reflected by a transparent screen to whomever is looking at the screen. But when you look at the screen with the smartphone oriented horizontally it looks like an image floating above the smartphone.
Note that Pepper's ghost is often called a hologram. In the strict scientific definition of a hologram it's not a hologram. However, it's become common usage to refer to it as a hologram.
There is a case where this is more like a hologram and that's when you use it to create a pyramid hologram as you can see I've done for the Princess Leia hologram.
The screen is plastic that I cut and folded to the needed shape and taped onto the phone. The plastic came from a roll I bought from an art store but you can also use plastic from packaging, transparencies from photocopying stores, clear covers for school reports, or whatever you can find.
Pepper's ghost Star Wars AT-ATs
Here I've made 3D models and animated the Star Wars AT-AT or Imperial Walkers from The Empire Strikes Back. It seemed appropriate since we had snow outside at the time and in the movie, the AT-ATs battle it out on an ice planet. I took the phone outdoors just as the sun was setting so that the animations would appear brightly.
As you can see, a problem was that the Pepper's ghost screen had to be close to the camera but the background was far away. In the necessary low light the foreground is in focus but the background is out of focus. In person, looking at it with the human eye the problem isn't as great.
I've uploaded the completed animation video to my YouTube channel and it's available here.
I created 3D models and animations in Blender 2.71 as shown below.
The blender file is available for download here and I place no
restrictions on its use:
Pepper's ghost ghosts
In this one I filmed myself in two different poses against a green screen and filtered me to look like ghosts using a video editor, Sony Vegas Movie Studio in my case but many others will do.
I've uploaded the completed video to my YouTube channel and it's available here.
Video - Pepper's Ghost on Smartphone
Here's a video of it in action along with step-by-step instructions for making one that will fit your phone.