Game Development Reference
In-Depth Information
as separate as possible. Let's see what the current options are for achieving such sepa‐
ration.
Types of Display
As just explained, 3D display technology depends on providing two distinct images,
one to each eye. In the next sections we'll discuss the common techniques used today.
Complementary-Color Anaglyphs
Anyone who saw a 3D movie in the 80s remembers the cheap red and blue glasses one
had to wear to get the effect. These were complementary-color anaglyphs . An anaglyph
is the technique of encoding the separate images in a single photograph or video frame
using color filters. The method calls for two horizontally shifted images to be viewed
simultaneously. The images will contain the two images tinted in opposite colors of the
scheme. While there are many color combinations that can be used, the most common
today are red and cyan. These colors are chosen because the cyan and red filters are the
most exclusive. Red and green filters were used earlier, but the green filter allows too
much red light to leak through. This can cause what is called binocular rivalry , where
your brain has a hard time figuring out which depth map to use. One way to illustrate
this is via the simple drawing of a transparent cube, as shown in Figure 24-6 .
Figure 24-6. Cube demonstrating binocular rivalry
If you focus on the cube in Figure 24-6 , your brain may start to flip between interpreting
the upper face as forward of the lower face, and the lower face being forward. While
this is caused by incomplete depth cues, the same uneasy feeling can be caused when
your brain receives leaks across the two channels in a stereoscopic display. As you can
imagine, this would be pretty annoying during a video game.
As the glasses don't require any electronics to do this, it is an example of passive 3D
technology. The major drawback of this method is that the red component of the images
is muted to the viewer. There are many improvements that can be made to the system
 
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