HA4 Task 4 - Mesh Construction

How are 3D models constructed? Describe and explain the different modelling techniques available to a 3

Polygonal Modelling

a polygon mesh is a collection of vertices, edges and faces which usual consist of triangles, quadrilaterals other simple polygons.

Primitive Modelling

A common method of creating a polygonal mesh is by connecting various primitives which is a predefined polygonal meshes created by the modelling environment. Common Primitives include: 

Cubes
Pyramids
Cylinders
Spheres
2D primitives, such as squares, triangles, and disks

Box modelling

The first is the subdivided tool which splits the faces and the edges of the shape into smaller pieces by adding new vertices. For example a square would be subdivided by adding one new vertex in the center and one on each edge creating four smaller squares.


The second tool is the extrude tool is used on a face or multiple faces of a shape. This create new faces the same size and the shape which is connected to each of the existing edges by face. And preforming the extrude operation on a square face.

Extrusion Modelling

A second common modelling method is sometimes referred to as extrusion modelling. In this method, the user creates a 2d shape which traces the outline of an object from a photograph or a drawing. The user then uses a second image of the subject from a different angle and extrudes the 2d shape into 3d, again following the shape’s outline. This method is especially common for creating faces and heads. In general, the artist will model half of the head and then duplicate the vertices, invert their location relative to some plane, and connect the two pieces together. This ensures that the model will be symmetrical.

Sketch Modelling

Sketch-based modelling is a method of creating 3D models for use in 3D computer graphics applications. Sketch-based modelling is differentiated from other types of 3D modelling by its interface - instead of creating a 3D model by directly editing polygons, the user draws a 2D shape which is converted to 3D automatically by the application.

3D Scanners 

3D scanners can be used to create high detailed meshes based on real- word items and people. But these devices are expensive and are normally used by researchers and industry professionals. But these devices can create high quality digital representations.