EXPLANATION OF 3D:
3D computer graphics are distinct from 2D computer graphics which are computer-based generations of digital images-mostly from two-dimensional models (such as 2D geometric models, text, and digital images) and by techniques specific to them. 3D computer graphics may stand for the branch of computer science that comprises such techniques, or for the models themselves. 3D is a three-dimensional virtual representation of objects stored in the
computer for the purposes of performing calculations and rendering images. In
general, the art of 3D graphics is akin to sculpting or photography, while the
art of 2D graphics is analogous to painting.
MODELING:
The modelling stage could be described as shaping individual objects that are
later used in the scene. There exist a number of modelling techniques:
Constructive
solid geometry (CSG) is a branch of solid modelling that deals with
representations of a solid object as a combination of simpler solid
objects. It is a procedural modelling technique used in 3D computer
graphics and CAD.
The simplest solid objects used for the representation are called
primitives. Typically they are the objects of simple shape: cuboids,
cylinders, prisms, pyramids, spheres, cones. The set of allowable
primitives may be restricted; e.g., curved shapes may be forbidden.
NURBS:
NURBS, short for nonuniform rational B-splines, are a computer
graphics technique for drawing curves. A NURBS curve is defined by a set
of weighted control points, the curve's order and a knot vector. NURBS are
generalizations of both B-splines and Bezier curves, with the primary
difference being the weighting of the control points which makes them
rational (non-rational B-splines are a special case of rational B-splines,
in practice most NURBS curves are non-rational).
modelling
POLYGON:
A polygon (from the Greek poly, for "many", and gonos, for "angle") is a
closed planar path composed of a finite number of sequential straight line
segments. The straight line segments that make up the polygon are called its modelling subdivision surfaces. In computer graphics,
subdivision surfaces are used to create smooth surfaces out of arbitrary
meshes. Subdivision surfaces are defined as the limit of an infinite
refinement process. They were introduced simultaneously by Edwin Catmull
and Jim Clark, and by Daniel Doo and Malcom Sabin in 1978. Little progress
was made until 1995, when Ulrich Reif solved subdivision surfaces
behaviour near extraordinary vertices.
MODELING PROCESSES:
Modelling processes may also include editing object surface or material
properties (e.g., color, luminosity, diffuse and specular shading
components-more commonly called roughness and shininess, reflection
characteristics, transparency or opacity, or index of refraction), adding
textures, bump-maps and other features. Additionally, modelling may include various activities related to preparing a 3D model
for animation. Objects may be fitted with a skeleton, a central framework of an
object with the capability of affecting the shape or movements of that object.
This aids in the process of animation, in that the movement of the skeleton will
automatically affect the corresponding portions of the model.
FORWARD KINETIC ANIMATION:
Forward kinematic animation is a method in 3D computer graphics for animating models. The essential concept of forward kinematic animation is that the positions of
particular parts of the model at a specified time are calculated from the
position and orientation of the object, together with any information on the
joints of an articulated model.
INVERSE KINETIC ANIMATION:
Inverse kinematic animation (IKA) refers to a process utilized in 3D computer graphic animation, to calculate the required articulation of a series of limbs or
joints, such that the end of the limb ends up in a particular location. In
contrast to forward kinematic animation, where each movement for each component must be planned, only the starting and ending locations of the limb are necessary.
(Source: free dictionary)
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