# Shared Flashcard Set

## Details

Modeling 1 Final
Flash cards for test. Ex'pression college.
48
Computer Science
Not Applicable
02/24/2010

Term
 Pros of Polygons
Definition
 simple, easy to learn, flexible to build any kind of shape
Term
 Cons of Polygons
Definition
 One normal per face leads to shading problems, easy to construct illegal geometry, can only do curves with huge number of polygons with soft edges.
Term
 Pros of Surfaces
Definition
 construct curved surfaces efficiently that render correctly, render with good results and efficiently, built in UV texture coordinates.
Term
 Cons of Surfaces
Definition
 Abstract, difficult to do a complex shape, need multiple shapes that can break apart.
Term
 Polygon Component Types:
Definition
 Vertices, Edges, Faces, Shells, Meshes, Normals, UVs
Term
 NURBS Component Types:
Definition
 CVs, Hull, Curve Point, Iso-Parm, Trimmed Edge
Term
 Subdivs Component Types
Definition
 Vertices, Edges, Faces, Creased Edge
Term
 Polygon tools:
Definition
 Extrude, Split Polygon, Insert Edge Loop, Append, Fill Hole
Term
 Surface Tools:
Definition
 Loft, Extrude, Boundary, Revolve, Detach, Attach
Term
 Types of Faces:
Definition
Term
 Types of Edges:
Definition
 Hard, Soft, Creased, Boundary, Shared
Term
 Types of Vertice:
Definition
 Winged, Pole, Star, Butterfly
Term
 Illegal Geometry:
Definition
 N-gon, Bow-tie, T-Formation, Winged Vertice, Lamina Face
Term
 Other Problems with Geometry:
Definition
 Internal or Hidden Faces, Non-Extruded Faces, Flipped Normals
Term
 What is Topology?
Definition
 How shape components are arranged to form the structure of a shape.
Term
 What is Good Topology?
Definition
 Refers to loops following the form of muscle and other parts of the character's anatomy(Loop Modeling).
Term
 Loops:
Definition
 Set of edges aligned end to end to form one line that travels along the surface of an object.
Term
 Loop Model Anomaly: Poles
Definition
 Vertices that have three edges, like the corner of a box.
Term
 Loop Model Anomaly: Stars
Definition
 vertices that have more than 4 connecting edges. (6 or more should be avoided)
Term
 Non-Manifold Polygon Geometry: T-shape
Definition
 A corner of one polygon connects in the middle on a side of another or when three faces share an edge.
Term
 Non-Manifold Polygon Geometry: Reversed Normals
Definition
 Occur when the normals of two adjoining faces don't face the same direction. The normals are essential to determine how an object should be shaded. Makes soft edges impossible.
Term
 Non-Manifold Polygon Geometry: Bow-Tie
Definition
 Occur when two polygons share a vertex but not an edge.
Term
 Non-Manifold Polygon Geometry: Lamina Face
Definition
 Are a pair of faces that share the same vertices and edges. Usually occur when using duplicate face incorrectly.
Term
 Non-Manifold Polygon Geometry: 3 other bad geometry
Definition
 five or more sided polygonspolygons that share vertices but not edgespolygons of a mesh that don't share any components
Term
 Geometry Components:
Definition
 Vertices, edges, faces, meshes, shell, UV's, normal
Term
 Vertices
Definition
 Polygon and Sub-divided Surface Points
Term
 Edges:
Definition
 Polygon and Sub-divided Surface sides/ Sub-divided Surface Edges can also be creased.
Term
 Faces:
Definition
 Individual Polygon and Sub-divided Surface Polygons
Term
 Meshes:
Definition
 A group of polygons that form a shape by sharing edges and vertices.
Term
 Shell:
Definition
 A group of faces within a mesh that share a group of UV coordinates. A mesh has at least one shell but can have more.
Term
 UV's:
Definition
 a 2D position of a 3D point on a shape(Used for texture mapping). U= width or horizontal component.V= height or vertical component.
Term
 Normal:
Definition
 The direction that a point on a shape is facing. Polygons have only one normal per face.
Term
 Parts of a basic NURB surface:
Definition
 Spline, Control Vertex(CV), Isoparametric Curves(Isoparms), Patches and Hull.
Term
 Spline:
Definition
 Curved line made up of segments and defined by control vertices(CV's).
Term
 Control Vertex:
Definition
 A point that controls the shape of a NURBS curve or surface at a particular point. CV's can be thought of as invisible magnets that pull a curve or surface towards them.
Term
 Isoparametric Curve:
Definition
 are lines running along the surface of a NURBS object in the U and V directions, showing the shape of the surface as defined by the CVs.
Term
 Patches:
Definition
 The area enclosed by four adjacent isoparms. Can also refer to the whole NURBS surface.
Term
 Hull:
Definition
 A line that connects CVs. It can be displayed to aid in modeling but is not required to edit a Nurb surface.
Term
 Sub-Divided Surfaces:
Definition
 developed to take advantage of the best of polygons and NURBS surfaces. Is basically a polygon mesh that is automatically smoothed like a NURB surface. Maya can have up to 6 levels of detail but more than three are rarely needed.
Term
 Geometry:
Definition
 refers to the types of shapes you can create.
Term
 3 most common types of Geometry:
Definition
 Polygons, NURBS and Sub-divided Surfaces
Term
 NURBS stands for:
Definition
 Non-Uniform Rational B-Spline
Term
 Tessellations:
Definition
 process in which a Nurb surface is eventually converted into polygons during Display or Rendering but the computer automatically determines how many polygons are needed to generate a smooth surface.
Term
 How do you close a gap between two NURBS?
Definition
 Use Attach or Fillet. Attach will snap them together while Fillet will add extra geometry that ties them together.
Term
 What's the process of creating a NURB trimmed surface?
Definition
 project curve onto a surface. Selecting geometry outside of projection will delete projection shape(AKA only selection will not be removed).
Term
 Flow:
Definition
 loops traveling along the shape representing the details of the structure underneath. In characters, flow will often change direction or switch from linear to radial.
Term
 What do Grid Flow and Good Topology mean?
Definition
 It means your grid and shape components are arranged to successfully represent the form and flow of your model.
Term
 What is Stitching with NURBS?
Definition
 connecting a network of patches into an organic shape but using the stitch function.
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