Of course, one of the most important aspects of VR is how the models are going to ``look'' when viewed on a display. This problem is divided into two parts. The first part involves determining where the points in the virtual world should appear on the display. This is accomplished by viewing transformations in Section 3.4, which are combined with other transformations in Section 3.5 to produce the final result. The second part involves how each part of the model should appear after taking into account lighting sources and surface properties that are defined in the virtual world. This is the rendering problem, which is covered in Chapter 7.