The 3-D Lighting Controls dialog box helps control the appearance of the 3-D image of the model in the lower right corner of the Working Area. The 3-D Lighting Controls dialog box is displayed by selecting View|3-D Lighting… There are six controls in the dialog box. The three controls on the left set the position of the light. The other three set different aspects of the light intensity.
Light Position
The coordinate system for the light has its origin in the center of the screen. X increases to the right. Y increases toward the top of the screen. Z increases out from the screen toward the viewer. The units of the coordinate system are arbitrary. They merely control the direction of the light.
Light Intensity
The light is considered to have three components: Ambient light, Diffuse light and Specular light. Ambient light is light that does not come from any particular direction. For instance, light from the sky would be considered ambient light. Diffuse light comes from a particular direction but is reflected evenly off a surface. However, surfaces directed at the light will receive more light than those directed away from the light. Specular light, like diffuse light is directional. However, it causes a bright spot on the surface on which it is shining.
