Consider the plot of the screen space from Example 32 which shows the screen space from Example 32. Some of the objects partially outside of the unit cube representation of the viewing frustum. The region inside of this unit cube contains the space that is visible to the viewer and is known as the visible region. Any objects that are outside of the visible region needs to be ignored from this point onwards in the viewing pipeline and any objects that lie partially outside need to be clipped to the edges of the visible region. This process is called clipping.
Fig. 72 Some objects are outside of the visible region and need to be clipped.#
In addition to clipping to the edges of the visible region the appearance of the virtual environment can be improved by removing those surfaces that show not be visible to the viewer. This process is called hidden surface determination.
