Modeling

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Modeling
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Topology
Topology describes an objects shape, number of
spans, and degree. For polygon objects this
includes vertex positions.
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Non-manifold topology
Non-manifold topology cannot be unfolded into a
continuous flat piece. Some modeling and rigging
operations in Maya will not work with
non-manifold geometry. Modeling operations that
can create non-manifold geometry include, extrude
edge, reverse normals, merge vertices, delete
face, and collapse face or edge.

• Example of Non-Manifold Topology
• More than 2 faces share an edge
• Two faces share a single vertex without sharing
  and edge
• Adjacent Faces have opposite normals

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Curves
Curves are defined by multiple points and deviate
from a straight path without any sharp breaks in
angularity.
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Splines
A Spline is a curved line shaped by weights. By
adjusting the number and position of weights, a
spline produces a smooth curve that passes
through a desired set of points.
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Controlled Curves
Splines are considered controlled curves because
they are created from a defining polygon made up
of control points. This defining polygon is
invisible, but contains weight information that
can be used to adjust the shape and angle of the
curve.
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Splines

• Linear Spline A spline made up of straight line
  segments connecting control points. Only 2
  control points are needed to generate a linear
  spline.
• Cardinal Spline A spline curve that always
  passes through all of its control points. A
  Tension value adjusts the tangents at each
  control point.
• B-Spline A spline curve that is defined and
  bounded by its control points, but it does not
  pass through them.
• Bezier Curve - A spline curve that always passes
  through all of its control points. A Bezier
  curve is controlled by lines tangent to the
  control points. Manipulating the tangents allows
  the user to control the direction and tension of
  the curve segment.
• NURBS A spline curve that does not pass through
  its control points. NURBS offer a high degree of
  curve control eat each control point. By default
  control vertices on a spline have an equal
  weight, this is referred to as a nonrational
  curve. The weight of control vertices on a NURBS
  curve can be modified and adjusted, this is
  referred to as a rational curve.

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Non Planar Polygons
A polygon is planar if all of its points lie in
the same plane. A triangle is always planer
because its 3 vertices define a plane. A polygon
is non planar if it has more that 3 vertices and
any of the other vertices are not in the same
plane.
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Invalid Geometry
Invalid Geometry occurs when there are vertices
that are not on an edge, or when there are edges
that are not part of a face. In Maya the polygon
cleanup function will correct invalid geometry
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Tessellation
Tessellation can be described as a converting a
3D surface into an polygon approximation of the
original surface. When a NURBS surface is
converted into a polygon surface, the surface is
tessellated into a polygon object. Most
renderers convert all surfaces to polygons at
render time.
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Nickeling
Nickeling describes the situation when faceting
is visible on low resolution polygon geometry.
Nickeling often occurs a a result of low
tessellation setting when converting a NURBS
surface to a polygon object.
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Procedural Modeling
Mathematical functions are sometimes used to
model natural like terrain, mountains and rock
formations. Procedural modeling is useful for
creating large areas of terrain that look natural
and non-repeating.
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3D Sculpting
The process of pushing a pulling control points
is referred to as 3D sculpting. This can be
accomplished by selecting individual control
points and moving them into a desired position.
In Maya the Sculpt Polygons Tool allows the user
to push a pull sections of polygon vertices with
a virtual brush.
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Mirroring
The process of duplicating surface across an axis
to create a symmetrical copy of the original
object is called mirroring. Mirroring is a
common method used to model symmetrical objects
like human figures, animals, and cars.
Model By Dave Komorowski
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Example Images
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Example Images