oCOSMO Cosmo 3DTM Manual

A SERVICE OF

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102

Chapter 9: Viewing the Scene

Figure 9-4 Perspective Explained

If you compare the height of an object in the near clipping plane to the height of the near

clipping plane, you see that the ratio is larger than the ratio of the height of the same

object in the far clipping plane to the height of the far clipping plane.

H

object

H

object

-------- > --------

H

near

H

far

Consequently, when you compare the size of the object to its surroundings, it appears

smaller in the distance.

Setting the Frustum

The frustum is the truncated pyramidal volume depicted in Figure 9-2. It is deﬁned by

four quantities, as shown in Figure 9-5:

• Distance to the near clip plane.

• Distance to the far clip plane.

• Horizontal ﬁeld of view.

• Vertical ﬁeld of view.