3. Geometric Theory

Geometry

There are many different steps to creating a 3D model. Wire frame, texture mapping and displaying the 3D. A wire frame model is a visual presentation of a 3D or physical object used in 3D modeling. It is created by having 3 or more points which are joined on the 3 axis (x, y, and z) in a 3D space. The object is projected onto the computer screen by drawing lines at the location of each edge. The term wireframe comes from designers using metal wire to represent the 3 dimensional shape of solid objects.3D wireframe allows to construct and manipulate solid surfaces.

Triangles always inhabit a single plane. The flat nature of triangles makes it simple to determine their surface normal, a three-dimensional vector perpendicular to the triangle's surface. Surface normals are useful for determining light transport in ray tracing. Some rendering systems use vertex normal’s instead of face normal’s to create a better-looking lighting system at the cost of more processing. In many systems only one of the normals is considered valid – the other side of the polygon is referred to as a back face, and can be made visible or invisible depending on the programmer’s desires.  

A texture map is applied (mapped) to the surface of a shape or polygon. This process is akin to applying patterned paper to a plain white box. Every vertex in a polygon is assigned a texture coordinate either via explicit assignment or by procedural definition. Image sampling locations are then put across the face of a polygon to produce a visual result that seems to have more richness than could otherwise be achieved with a limited number of polygons. Multitexturing is the use of more than one texture at a time on a polygon. For instance, a light map texture may be used to light a surface as an alternative to recalculating that lighting every time the surface is rendered. This is then followed by displaying the 3D image by usually rendering the 3D model so that it can be displayed in its full glory with all the shading, texture mapping etc. This will then show you all the things you have done to it in its entirety that you may not have seen before.