5.3.4 Cone lights

Figure 5.3.9: The Accurate Intensity options for a cone light.

Figure 5.3.10: The Cone Light parameters

Figure 5.3.11: A scene rendered with a cone light.

When Cone is selected in the Type menu, the Cone Light options are presented as shown in Figures 5.3.9 and 5.3.10.

Intensity tab

The Accurate Intensity options for a cone light are the same as those for a point light.

Parameters tab

The two parameters in this group of options define the physical shape of the cone light, which consists of two cones, an outer and an inner cone. The inner cone defines the volume where the light intensity remains constant relative to its distance from the axis of the cone. From the inner to the outer cone, the light intensity decreases, and fades completely at the outer cone.

Outer Angle, Inner Angle: These slider parameters determine the angle for the outer and inner cones of a cone light, and range from 0° to 180°. The two are interdependent, but the inner angle cannot be greater than the outer angle, and it cannot be less than half of the outer angle. If one slider is set to a value that violates the above conditions, the other is adjusted automatically. The values entered for the outer and inner angles and the coordinates for the Location and the Center Of Interest are also used to construct the shape of a cone light displayed in wire frame.

A scene with a cone light is shown in Figure 5.3.11. In this example the cone light is used to simulate a desk lamp. Figure 5.3.12 shows the Light Parameters dialog for that light. The falloff is set to Square, which relates to the behavior of light in the real world.

Note that the Center Of Interest of the light, drawn with an arrow in the project window, is located approximately on the tabletop surface. At that point, the cone light illuminates the surface at the intensity set in the Simple intensity field, in this case 150%. As with the distant light example, an additional fill light is used to improve the shading of areas not illuminated enough. You can recreate this rendering and look at the light parameters by loading sample file “Cone.fmz.”