ELSA GLoria-L, User Manual

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All About Graphics
ELSA GLoria-L, -L/MX, -XL, -XXL
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All About Graphics
3D Graphics Representation
The 3D Pipeline
What actually happens when a monitor displays a 3D object? The data describing the 3D
object are passed through what is known as the 3D pipeline, in which the mathematical
calculations for its representation in space and perspective on the monitor are carried
out. What happens in detail?
Start: The object data
The pipeline starts at the object. The object description is made up of the data (points).
Tesselation
In the first step, the object is broken down into a number of polygons or triangles. The
vertices of the triangles are described by coordinate points (x, y and z) with the 'z' value
containing the depth information. Depending on the representation, these vertices also
contain information concerning the material and texture. The volume of data to be pro-
cessed increases enormously because of this conversion of the image information.
Geometrical transformation
This part of the 3D pipeline is very processor-intensive, as all the calculations for the 3D
scene are carried out at this stage. Simplified, it comprises of the following steps:
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Illumination ––The illumination of the scene by different light sources is calcu-
lated.
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Transformation ––In transformation, the objects are aligned in perspective as seen
from the observer's point of view.
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Back face culling ––This process computes hidden surfaces resulting from the
observation perspective chosen. Any object having an invisible front surface is
omitted.
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3D clipping ––In this process, each polygon is checked to determine whether it is
partially or fully invisible. The invisible faces or parts of objects will be removed.
Object data Tesselation
Geometrical
transformation
Rendering
Display
on the monitor