Modeling Concepts 105 engravings with special texture maps called bump maps or displacement maps. You will learn about these maps in Chapter 7, "Materials and Mapping." Don't worry about these things yet, though. Most people begin by putting all the details they can into their model, and as they gain more experience, they start to realize that some of the modeling work can be deferred until the texturing phase. Figure 4.1 The level of detail in a model depends on how much of the model is seen. Modeling Concepts To get a foothold in modeling, you will need to understand a number of things. If you are not new to CG or are desperate to get started, feel free to skip ahead and start modeling. However, you still might want to peruse this section for some concepts and terms that may make things easier for you in the coming exercises. Polygons A polygon is a surface created by connecting three or more points in 3D space. This flat surface connects to other polygons to form more intricate surfaces. In Figure 4.2, you see a sphere. The facets of the sphere are polygons, all connected at common edges at the cor- rect angles and in the proper arrangement to make a sphere. The points that generate a polygon are called vertices. The lines that connect the points are called edges. If the polygon has three vertices, its surface is called a face. Polygons are made up of triangular faces by design. In the example of the sphere in Figure 4.2, the polygon's facets all have four vertices. Figure 4.3 shows the same sphere with one face selected. See how the face is half of the polygon, using three of its vertices. The more polygons you have in a model, the more detailed it becomes. However, greater numbers of polygons tax your system and take longer to render. This is where