Hitachi demos 3D real-world object projector

I believe the writeup is misrepresenting how this works. It states that the system projects "on to" the object, however given that their example is an egg, which has a Lambertian (matte) surface, you would not be able to present different projections to viewers at different angles.

From the diagram, it looks like they're projecting onto a glass screen in front of the object, and it appears to be superimposed on the object using the same approach as the Pepper's ghost box [1].

Of course I may be mistaken. This is just an educated guess.

And regardless, this sounds like a really cool technology.

[1] http://en.wikipedia.org/wiki/Peppers_ghost

EDIT: From the Google Translate of the Japanese press-release, this looks correct, they are using a half-silvered mirror so you can see the egg-through the mirror and also the projection reflected on the mirror

" Hitachi, respond to these needs, aiming to represent the object close to the actual images from nature, using a half mirror for combining multiple lenses and translucent, the image information captured in real-space projection of 24 units has enabled it to be displayed".

This isn't the same as holographic 3D like the article claims. It is true that it will look different from different angles, but that isn't all that impressive. You could say that a television is sort of like a painting that moves. If you were to take a painting and then wrap it into a cylindrical shape, that wouldn't make it 3D, it would just make it differently shaped.

Likewise, this technology just projects onto on oddly shaped object. It doesn't magically add any of the depth feeling that you get from, for example, watching a movie with 3D glasses.

The reason this is so difficult is that when you view a real object, it reflects light in all directions so that your eyes actually see two different images when you look at it from two different angles (your two eyes, or any other arbitrary viewing angle).

Imagine that you were trying to make a projector that no human would be able to distinguish from a real window. Imagine that you had the requirement that the user would have to be able to look in different directions out the window and get different views just like a normal window would. What you would have to do is create pixels that can project different colors in different directions and maintain complete control over which color was projected in each direction. In short, you must create a pixel that will look different depending on which direction you view it from.

If you think of it this way, you basically would have to control each pixel as a series of subpixels, each subpixel pointing in a specific direction. To make it realistic, you would probably need thousands of subpixels for each pixel, increasing the requirement for number of pixels by thousands of times and decreasing the required minimum size by thousands of times. Also, you have to make the subpixels point in only one direction.

And that, my friends, is almost impossible.