Game Development Reference
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Figure 3.11 Two parallelepipeds and not a group of lines on a plane sheet!
Information of depth
Static cues
Parallax caused by movement
Light and shadows
Texture gradient
Variation of visibility
Figure 3.12 Cues that help in perceiving depth in the three-dimensional space
When the optical axes converge on an object, the brain obtains ghost images of
other objects distant from this object. What does the brain do with these ghost images?
In practice, it takes no mental note of these images. Mainly, even when you look into
the distance, you always see two blurred images of your nose but you do not pay
attention to these images…except now…it will disturb you if you did so! In case of
natural vision, the eyes do not accommodate ghost images (the corresponding objects
are too far or too close). But it is not the same in case of a screen where all images
are clear and are at a same distance. We will discuss this problem when we talk about
creating 3D images. Normally, the convergence of visual axes is ordered by the brain,
but we can physically make these axes diverge and see that images get split: Look at
this text and press your finger on one eye to turn it. The images will be split; merging
them will no longer be possible.
Let's analyse our natural visionmore geometrically and optically using Figure 3.14.
Here, an observer looks at point F . The (horizontal) disparity quantifies the notion of
difference between images by measuring the distances. Figure 3.14 illustrates retinal
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