ELSA Erazor II - Manual (Page 39)

Glossary
ELSA ERAZOR II and ELSA VICTORY Erazor LT
33
average colors for inserted pixels). Horizontal
interpolation is relatively easy to perform, since
the pixels are drawn to the screen in lines.
Vertical interpolation is more difficult and
requires a complete pixel line to be buffered.
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MIP mapping – In MIP mapping a number of
textures are assigned to an object depending
on distance. The representation of the object
becomes more detailed as the observer
approaches the object.
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Multifrequency/Multisync monitor – A
monitor that can be operated at various hori-
zontal scan frequencies, or that automatically
adapts itself to different video signals (resolu-
tions).
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OpenGL – 3D software interface (3D API).
E.g. implemented in Windows NT and avail-
able for Windows 95. Based on Iris GL from Sil-
icon Graphics and licensed from Microsoft.
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Page Flipping – The image generated in the
➞back buffer is displayed
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PCI bus – Abbreviation of Peripheral Compo-
nent Interconnect Bus. An advanced bus sys-
tem, i.e. a system of parallel data lines to
transfer information between individual system
components, especially to expansion boards.
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Phong shading – ➞ 'Shading'.
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Pixel – Picture element. Dot in the image.
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Pixel frequency – Pixel clock frequency
(number of pixels drawn per second in MHz).
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Primitive – Simple, polygonal geometrical
object, such as a triangle. 3D landscapes are
generally broken down into triangles.
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RAM – Abbreviation of Random Access Mem-
ory. Chip memory of a computer or expansion
board that can be read from and written to
(unlike ROM = Read Only Memory).
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RAMDAC – The RAMDAC converts the digital
signals to analog signals on a graphics board.
VGA monitors are only capable of processing
analog signals.
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RealColor – RealColor normally designates a
15-bpp or 16-bpp (bits per pixel) graphics mode,
i.e. 32,768 or 65,536 colors).
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Refresh rate – or image refresh frequency (in
Hz) indicates how many times per second an
image on the monitor is refreshed.
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Rendering – Process for calculating the repre-
sentation of a 3D scene, in which the position
and color of each point in space is determined.
The depth information is held in the ➞Z buffer,
the color and size information is held in the
➞frame buffer.
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Resolution – The number of pixels in horizon-
tal and vertical direction on the screen, for
example 640 horizontal by 480 vertical pixels
(640 x 480).
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RGB – Color information is saved in the Red/
Green/Blue color format.
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ROM – Abbreviation of Read Only Memory.
Semiconductor memory that can only be read
and not written to.
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Shading – Shading or rendering is a way to
define the colors on curved surfaces in order to
give an object a natural appearance. To
achieve this, the surfaces are subdivided into
many small triangles. The three most impor-
tant 3D shading methods differ in the algorithm
used to apply colors to these triangles:
Flat shading: the triangles are uniformly col-
ored.
Gouraud shading: The color shades on a trian-
gle are calculated by interpolating the vertex
colors, resulting in a smooth appearance of the
surface.
Phong shading: the color shades on a triangle