Lighting in 3ds Max simulates natural lighting. However, standard lights are simpler than natural lighting. Using photometric lights with a radiosity solutionwith your lights provides a better model of the real world.
The intensity of a standard light is its HSV Value. At full value (255), the light is at its brightest; at 0, the light is completely dark.
The intensity of a photometric light is set by a real-world intensity value, measured in either lumens, candelas, or lux. See Intensity/Color/Attenuation Rollout (Photometric Lights).
3ds Max uses a vector from the light object to the face, along with the face normal, to calculate the angle of incidence.
A surface is fully illuminated when the angle of incidence is 0 degrees (that is, the light source strikes the surface perpendicularly). If the angle of incidence increases, attenuation is in effect, or if the light has a color, the surface intensity can be reduced.
In other words, the position and orientation of the light, relative to the object, are what control the angle of incidence in a scene. The Place Highlight command is one way to fine-tune the location of a light.
For standard lights, attenuation is turned off by default. To shade or render a scene with attenuation, you turn it on for one or more lights. All types of standard lights support attenuation. You can set explicitly where attenuation begins and where it ends. This is partly so you don’t have to worry about setting up strictly realistic distances between light objects and the objects they illuminate. More importantly, this feature lets you fine-tune the effect of attenuation.
In outdoor scenes, attenuation can enhance the effect of distance. (Another way to model environmental effects is to use the atmospheric settings when you render. See Environment and Atmosphere Effects.) In an indoor setting, attenuation is useful for low-intensity light sources such as candles.
Photometric lights always attenuate, using an inverse-square falloff, as in nature. (In the case of the IES Sun Light, its great intensity makes its attenuation hardly apparent.)
Reflected Light and Ambient Light
Rendering with the default renderer and standard lights does not calculate the effect of lights reflected from objects in the scene. Because of this, lighting a scene with standard lights often requires you to add more light objects than would be needed in real life. You can, however, use radiosity to show the results of reflected light.
When you do not use a radiosity solution, you can use the Environment panel to adjust the color and intensity of ambient light. Ambient light affects contrast. The higher the intensity of ambient light, the lower the contrast in the scene. The color of ambient light tints the scene. Sometimes ambient light is bounced light that gets its color from other objects in the scene. Most of the time, however, the color of ambient light should be the complement of the color of the principal light source for the scene.
You can set the color of 3ds Max lights. You can use the RGB values for color temperatures as a guide for the principal lighting of a scene; see Properties of Light. Be aware, however, that we tend to perceive scenes as always being lit by white light (this is a perceptual phenomenon known as color constancy), so accurately reproducing the color of a light source can make the rendered scene appear to be tinted oddly. Use the light source values as a general guideline only.
