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Here you will find some of the most used 3D terms explained to some degree.This section is especially meant to be used by novices to 3D.Note that many terms are missing from this list and will be added with time.Before you start reading this, make sure that you are aware of the following often, misused facts:
k = kilo = 1000
K = Kilo = 1024
a bit is the smollest data unit which can either be on or off
1 byte = 8 bits
1kb = kilobit = 1 000 bit
1kB = kiloByte = 1 000 byte
1Kb = Kilobit = 1 024 bit
1KB = KiloByte = 1 024 byte
1Mb = Megabit = 1 048 576 bit
1MB = MegaByte = 1 048 576 byte
2D
see Bitmap
3D
Three-dimensional
8 bit image
A digital image in which every pixel is able to show one out of 256 possible colors(2 to the power of 8).In this kind of image each pixel fills 8 bits of memeory.
16/24 bit image
The same as above.Every pixel in the 24 bit image is able to show one out of 16,7mill(2 to the power of 24 = 16 777 216 colors) of colors so every pixel fills 24 bit of memeory.
3DMF
3D metafile.Apple's native file format for Quick Draw 3D.
Any Quick Draw 3D compatible program can use objects stored
in this format(complete with textures).
3D Digitise
3D digitiser "scans" a physical object and import its
vital statistics to a raytracing package, where the model is
tidied up before texturs and other effects are added.
A
Algorithm
A step by step method of solving a mathematical
problem.For exemple the raytracing algorithm is able to calculate how light rays will behave on its way in a certain environment.
Aliasing
A digital phenomenon. In the realm of graphics,
when trying to display an image on a portion of the screen
where the resolution is too low to display its details
correctly, aliasing can occur. Edges look jagged instead of
smooth.
Alpha Channel
In a 32-bit image, the alpha channel is an extra 8-bits of
information that is sent to the screen in the RGB color
mode. 8-bits are used for storing
the red color information, 8 are used for the
green information and 8 are used for the blue
color information. The remaining 8 bits can be
used to store masking
information for compositing images together.It is
particularly useful in communicating transparency in
objects and it is commonly used as graphic layer which is layred over a
background or an animation or live video.
Ambient light
Light that exists everywhere without a particular
source. Ambient light does not cast shadows, but
fills in the shadowed areas of a scene.
Anti-aliasing
A graphics procedure designed to eliminate a
stair-stepping effect, known as jaggies(aliasing),that
appear when pixels of contrasting colors occur next to one another.
Anti aliasing works by blurring pixels at edges of lines
to make the difference between two color areas less
dramatic.
Aspect Ratio
Aspect Ratio - Is the resolution of the image also number of pixels(in both height and width) making up an image.
B
Bevel
(3D modeling operation)A bevel removes sharp edges from an extruded
object by adding additional material around the surrounding faces.
B-Spline
(spline surface) B-Spline is a spline surface curve which rarely
passes through its control points.
Bitmap
A 2D digital image. A bitmap exists in the computer's memory as an exact
representation of the image.A bitmap consists of series of bits and bytes that
form pixels.Every pixel expresses a level of color, whether it is one bit( 2
possible colors) or 16bit (2*16=65536 possible colors to be expressed by every
pixel)or 24bit(16,7millions of colors) and so on.All the final renders are bitmaps, most of the graphics you see in f.ex. a multimadia programs are bitmaps.
Booleans
(3D modeling operation) General referance to the ability
to "carve" the shape of one object out of another.
Bounding box
A simple representation of a 3D object as a hollow box.Very usefull in scenes with lots of polygons as as it speeds up the process of f.ex. changing Views.
Bump Mapping
A technique used to simulate rough
or bumpy texures with irregularites in shading.Bump maps
control the actual texture of the surface.Without a bump map
the surface of a sphere is treated like a sphere, but with one
the sphere could become a textured object like an orange or stone.
C
Color depth
The number of possible colors that can be shown in a particular image.F.ex. an 8 bit image can represent a total of 256 colors or a 16 bit image can represent a total of 65 536 colors.
Cross-section
The 2D outline that represents the basic shape of an 3D extrusion
D
Depth cueing
Depth cueing changes the color and hue of an object
in accordance with the object«s distance from the viewer.
Diffuse
Light that is evenly reflected from an object's surface
visible regardless of the angle from which it is viewed.
Dither
A process which enables a system to create the
illusion of displaying more colors than it can actually
generate, dithering is accomplished by placing dots of
different colors next to each other in a variety of
patterns. For instance, placing red and yellow dots next to
each other in a checkerboard pattern will create an
impression of the color orange.
DXF
The most common 3D model file format, inferior to 3DMF in that
it does not include mapping information or lightning and cameras.
DXF also does not support hierarchical linking or spline geometry.
E
Extruding
(3D modeling operation) Squeezing out a new 3D object of the
first drawn 2D extrusion profile.F.ex a cirkel will give you a cylinder when extruded.
F
Face(Facet)
Face(Facet) is a collection of 3 or more verteces which form a
small triangle(ploygon) surface. Most 3D programs use 3 sided faces, but
some support 4 sided ones too. A collection of faces is refered
to as a mesh. Each face also has a special entity tied to it called
a normal. The normal defines which side of the face is considered
to be the inside of an object, and which is the outside.Facets are clearly visible
in wireframes and flat shading rendering modes.
Flat shading
(rendering process)The flat shading algorithm calculates
one color for each polygon in the model, based on the texture used and
its position relative to light sources.The result gives a better
indication of how the light source will affect the final render.The flat shading
redering is one the fastest rendering algorithms.
Frame Rate
(animation) The number of frames per second(fps) in
an animation.
Frequency
(texture mapping) A measurement of the number of times certain
textural characteristics repeat themselvs within a fixed area.
G
Glow
A surface property that creates the illusion of light emanating from an object.
Gouraud Shading
(rendering process)Also known as smooth shading,
this is a method of shading polygons. In Gouraud shading, colors are
first calculated at each of the vertices in a polygon. Then
the surface of the polygon is shaded to give a smooth
transition between the different colors at each vertex.It can«t
handle texture maps, transparency, or shadows.
H
Hierarchical linking
Connecting parts of a model so that
they move in relation to each other.In a character model, the arms are
linked to the body.The movement of the child objects(here arms) depends,
in part, on movement of the parent(here the body).
I
Image mapping
A two-dimensional image applied to the surface of
an object. Image mapping is usefull for
placing pictures or text onto objects, for
example, a label on a model of a bottle.
Inverse Kinematics
(animation) Method of model animation that helps
in creating more natural movements.With IK, moving character's
hand will make the arm follow the hand in a natural matter.
J
K
Keyframe
(animation) Frame that defines the beginning or ending of
a motion or sequence.
L
Lathing
Lathing (3D modeling operation) creates a new object from a 2D profile
by rotating it around an axis.Very usefull for creating objects like glasses or vases.
Lofting
Lofting see skinning
M
Map(mapping)
Applaying an image onto the surface of an object.
Mesh
Mesh is a collection of faces (patches) which describe an object. The faces
are arranged in such a way that they form the outside surface
of that object.
Metaballs
(3D modeling operation) Metaballs simply uses spheres to create
organic models by indicating the amount of fusion between the various
spheres(by assigning colors to spheres).Very usefull for creating realistic looking animals.
Metamesh
Metamesh is the smooth surface of a metaball model.
MIP Mapping
When a texture is applied to an object, it often has to
be resized or stretched to fit.This process degrades the texture
image.Mip mapping creates three or more copies(called MIP levels)
of the texture, each of a different size, so that the best fitting copy
can be used.
Morphing
In 3D the changing of one shape to another.
Motion Capture
A process by which an object's motion
through 3D space is digitized. Sometimes mechanical systems
are used, but the most common capture method uses an array
of video cameras operating in infrared frequencies to
capture the motion of special markers (usually balls of
reflective tape) in 3D space. The object being captured (a
human making a pitching motion, for instance), has several
reflective balls attached at key points, like the head,
hands, joints, etc., and is then filmed by the cameras
The end result from motion
capture is basically the motion of the skeleton of the
thing captured, around which can be "wrapped" a 3D modeled
character, to generate extremely life-like animation.
Motion Path
(animation)A curved line or many linked lines drawn on screen which represents the motion path of an object.
MPEG
(Moving Pictures Experts Group) A standard for
compressing full-motion video, it enables far more video to
be stored in a given amount of space than when
uncompressed. Like JPEG, MPEG is "lossy" and MPEG
compressed video is of lower quality than standard VHS
video.
N
O
Object
An object can be a collection of points, splines and patches
(spline modelers) or a collection of polygons(polygonal modelers).
Both can be managed as a whole.
Object tree
A group of linked objects. A object tree can
contain any number of parent and child objects. A
model containing object trees is called a
hierarchical model.
P
Particle System
(animation) Particle systems work by defining states
and rules of behavior for each particle or group of particles.
A particle can usually be anything, from a point to an object.
Objects and particles can usually emit other particles.PS is particularly
good for simulating and animating differant phenomena,
such as rain, fire smoke or flocks of birds or explosions.For example
instead of exploding an object into ten large pices and creating
individual motion path for each piece, a particle system makes it
simple to blow it up into hundreds of smaller pieces, without having
to define individual motion path for each piece.Every piece can then emit
other particel(s) as smoke trails.
Patch
A patch is a closed figure(area) made of 3 or 4 splines
(3 or 4 connected points) that contains a patch entity.A surface
can be a colletion of patches.
Pixel
A pixel is the smollest element a dot that makes up the image.A pixel can only show one color value, depending upon how much storage space is allocated for it.For exemple an 24 bit image with the aspect ratio of 640*480 (640 pixels wide times 480 pixels high) consist of in total 307 200 pixels.Every pixel fills 24 bit in memeory so the entire image needs 307 200 times 24 = 7 372 800 bits = 921 600 bytes of memeory.
Perspective-correct texture mapping
Texture maps that continually
change to match the perspective of the viewer.
Phong Shading
(rendering process)A method of shading that
applies the phong lighting model not to every polygon, but to
every pixel of every polygon. Some phong shading algorithms
can make 3D models look indistinguishable from the real thing.
It's often bad at transparency and most phong based algorithms
can't produce shadows.
Polygon
A three or more sided 2D shape from which 3D
environments are created, and which can then be represented
on a 2D screen.Used to define the surface of a model.
Polygonal Modelers
A modeling application in which surfaces are
defined as a collection of tiny squares or triangles(polygons).
Polygonal modelers are best for objects that don't change shape,
like ships, buildings, but are not good at organic shapes.
Prmitive
A basic geometric form, such as a cube or sphere,
used as a basis for constructing compound 3D objects such
as buildings, ships, snowman.
Q
Quick Draw 3D
Quick Draw 3D is the first PowerPC RISC chip specific
API from Apple.It consists of three extensions:QuickDraw 3D,
QuickDraw 3D Accelerator and QuickDraw 3D Viewer.As standard,
QuickDraw 3D includes Gouraud shading, then objects stored in 3DMF
can be moved, rotated and resized in real time.
R
Raster image
- see Bitmapp
Raytracing
(rendering process)A way of rendering a 3D image
which follows the path of every ray of light.The light beam may be
absorbed, reflected, or otherwise affected to some degree by every
object it strikes.This produces the best image quality af all
rendering algorithms.
Reflectivity
The degree to which an object bounces light back
from its surfaces.
Refraction
As a light wave passes from air through another medium
such as water or thick glass, it seems to bend or turn to a certain
degree.This phenomenon is known as refraction.
Render
When the computer creates a graphic representation
( 2D bitmapped image) from all the information contained
in 3D wireframe scene.
Resolution
A measure of the density of pixels on a screen,
measured by two numbers, which represent the number of
pixels available across and down the screen (e.g. 640x480).
Many computers can generate video output at a variety
of resolutions.
Rotoscoping
A way of creating animation by tracing the
movements of human actors from film or video. Previous to
the advent of motion capture, this was the best way of
getting smooth, humanlike animation
S
Scene
The 2D screen projection of your 3D environment: models,
cameras, lights... .
Skinning
(3D modeling operation) Streching a surface(skin) over
interior cross section(for instance 2D ribs).Also called lofting.
Specular
The "highlight" of any object with a shiny surface;
light that reflects nonuniformly in specific directions dependind
on the surface roughness.
Spline
An editable curve used to define the shape of a model.
Also called curve or spline patch.
Spline Modelers
(surface modeler) A modeling application in which surfaces are defined as splines and points.In general, spline based modellers produce smoother, rounder shapes than polygonal based modellers.This make them more suitable for making organic forms and animating liquids.
Sweeping
(3D modeling operation) Combines lathing and extruding
to create, for instance, springs or spirals.
T
Texture Map
A special kind of bit-map, texture-maps are
laid over or wrapped around polygons in 3D.Values from the
texture can determine or affect any surface characteristic,
including color, reflectivity, transparency or bumpiness.
Transparency
The measure of an object's ability to transmit
light through its surfaces.Also refferd to as Transmitivity.
Transmitivity
The measure of an object's ability to transmit light
through its surfaces.Also refferd to as Transparency.
U
V
Vertex
A specific point in 3D space.Vertex implies a corner point,
where plane polygons join.
Voxel
Beyond the polygonal texture-mapped world lies the
voxel. A voxel is a 3D pixel, and can be compared to a world made of tiny
little lego blocks. Voxel technology requires processing
power far beyond that of the next-generation systems.
W
Wireframe
(rendering process) A mesh representation of a 3D object.
Displayes only the splines or polygons that make up the model.
X
Y
Z
