Programming WPF, 2nd Edition

Cameras

You must set the Viewport3D's Camera property to one of the three available camera types: PerspectiveCamera, OrthographicCamera, or MatrixCamera. The type of camera determines how the 3D model will be turned into a 2D image on-screen.

The PerspectiveCamera is often the most natural choice. With this camera, the farther away objects are, the smaller they appear. Because that's how things look in real life, this produces a reasonably natural-looking image.

The OrthographicCamera uses a more simplistic approach. A 3D object of a particular size will always be rendered at exactly the same size, regardless of how far away it is. This tends to produce rather unnatural-looking images, but it can occasionally be useful—sometimes consistency is more important than a natural appearance. If you are rendering 3D models representing the design of something physical, such as a planned piece of woodwork or the layout of a room, you might want objects of the same size in the model to appear the same size on-screen. Likewise, if you are producing a 3D graph, consistency of size might be more important than realism. An OrthographicCamera can guarantee this, whereas a PerspectiveCamera can, by design, show equal-size objects as different sizes on-screen. Figure 17-1 shows an example—on the left is a series of identical columns rendered with a PerspectiveCamera, and on the right is the same model as shown by an OrthographicCamera.

Figure 17-1. PerspectiveCamera and OrthographicCamera

If you are ...