MS. WILLIAMS Anatomy of a 3D Model

3D Model 3D Models are one of the essential building blocks of 3D computer graphics. Without them there would be no computer animation

What is a 3D Model? A 3D Model is a mathematical representation of any three-dimensional object (real or imagined) in a 3D software environment. Unlike a 2D image, 3D models can be viewed in specialized software suites( 3ds Max) from any angle, and can be scaled, rotated, or freely modified. The process of creating and shaping a 3D model is known as 3d modeling.

Types of Model There are two primary types of 3D models that are used in the film & games industry, the most apparent differences being in the way they're created and manipulated 1. NURBS Surface 2. Polygonal Model

NURBS Surface A Non-uniform rational B- spline, or NURBS surface is a smooth surface model created through the use of Bezier curves (like a 3D version of the MS Paint pen tool. To form a NURBS surface, the artist draws two or more curves in 3D space Which can be manipulated by moving handles called control vertices (CVs) along the x, y, or z axis. NURBS surfaces have the highest level of mathematical precision, and are therefore most commonly used in modeling for engineering and automotive design. We will discuss NURBS in Detail at a later date.

What is a Polygon? The word comes from the Greek and it means “ many sides”. A polygon is a geometric figure… 1. It is made of straight line segments. 2. Each segment touches exactly two other segments, one at each of its endpoints. 3. It is closed -- it divides the plane into two distinct regions, one inside and the other outside.

Polygonal Modeling When you work with surface-modeling techniques, understanding the basic concepts means understanding the geometric modeling of all 3D computer graphics. Computers are very good of manipulating numbers but very bad at subjective concepts Example:/ If I told you to make a shape more voluptuous or more petal like. It would be easy to follow instructions. If I said make the shape twice as long it would be easier to follow.

Polygonal Model 3D modeling programs are based on numerical and the manipulation of shapes. Polygonal Models are the most common models that we will be using in this class. They are used in animation, film and gaming. Polygonal models are very similar to the geometric shapes

Polygonal Model Just like a basic geometric cube, 3D polygonal models are comprised of FACES, EDGES, and VERTICES.

FACES EDGES A polygon by which a solid object is bound. Example, a cube has six faces. Each face is a square. Any point on the surface of a 3D model where two polygonal faces meet. Polygonal Model

The point of intersection between two or more edges is called a vertex Vertices

Polygonal Modeling A few basic concepts that is involved in all computer graphics 1. Point 2. Plane 3. Line 4. Vertex 5. Vertices 6. Polygon

Point Plane A point specifies only location; it has no length, width, or depth. We usually represent a point with a dot on paper, but the dot we make has some dimension, while a true point has dimension. A plane is a flat, two-dimensional object. We often represent a plane by a piece of paper, a blackboard, or the top of a desk. In fact, none of these is actually a plane, because a plane must continue infinitely in all directions and have no thickness at all. A plane can be defined by two intersecting lines Polygonal Model

Line Vertex has only one dimension: length. It continues forever in two directions (so it has infinite length), but it has no width at all A vertex is the point where two sides of a polygon meet. Polygonal Model