Create a Point Light

A point light radiates light in all directions, and is useful for generating soft shadows. Common examples include light bulbs and candles.

Figure 1. Example of a Point Light with an ISO of 200
Turn on the Materials display mode, so you can see the changes as they are applied.

You may want to decrease the Intensity of the global environment if you plan to add lights to your scene.

  1. On the ribbon, click the Rendering tab.
  2. Click the Light icon.
  3. In the modeling window, click to place the light.
    Tip: To reposition the light, drag the Position point.
  4. In the Control Panel, for Type, select Point.
  5. To define the intensity of the light source, in the guide bar, enter a Power.
    Note: This feature only applies to specific units of power, and is not Unitless.
  6. In the guide bar, enter a Light Diameter.
  7. In the Control Panel, define the other parameters.
  8. Right-click and mouse through the check mark to exit, or double-right-click.

Light Parameters

Power Unit
The default is Unitless, which measures intensity using arbitrary units that do not directly relate to the power output of a lamp or any other such physical measurement.

To simulate a real world commercial light bulb, select a specific unit of power (Lumens, Candelas, etc.).

Efficacy
(Only applies to Watts and Watts/sr.)

Define the luminosity of the light source in lm/Watt.

Tip: Specific light sources have specific values (e.g., a 100-Watt tungsten incandescent lamp has an efficacy of 12-18 lm/W, while a good LED light might have an efficacy of about 100 lm/W). You can find a table of data at http://en.wikipedia.org/wiki/Luminous_efficacy.
Attenuation
Define the loss of light intensity based on the light-object distance.
None: The light intensity remains the same regardless of the light-object distance.
Inverse: The light intensity decreases as distance increases.
Inverse Square (default): Simulate the natural behavior of physical light, where light intensity decreases based on the distance squared.
Color
Define the color of the light by choosing a plain color from the color palette. It is recommended to use subtle, light colors for better results.
Caustics Photons
Caustics is a technique that mimics real light by calculating photons that start at a light source. If Caustic Photons is enabled, these photons are reflected, refracted, and bounce off the surface of a mirror, for example. Some lights in your scene may not produce caustics; for these, disable Caustics Photons to save rendering time.
Note: This feature is not currently available in GPU+CPU mode.
Figure 2. Caustics Off
Figure 3. Caustics On
Shadow
By default, all objects cast and receive shadows when illuminated by a light source; however, there may be situations where this is undesirable. For instance, certain objects cannot produce a visible shadow due to the viewing position. Excluding these objects from shadow calculations can result in improved rendering performance, both in terms of increased speed and reduced memory usage.
Note: This option only applies to Raytracing; it does not affect the Interactive Rendering or Full (Progressive) rendering engines.
Reflection Based Positioning
  1. Select a light.
  2. Do one of the following:
    • To place the light perpendicular to the point where you will click, for the Placement Method, select Illumination.
    • To place the light in the opposite direction, for the Placement Method, select Reflection. In the figure below, if A is the camera and O the point where you click, the light will be placed at point B. This feature allows the camera to receive the maximum amount of reflection.
  3. To place the light on a surface, click the Place on Surface button, and then click the surface.
  4. Define OB:
    • To make OB equal to AO, for the Placement Distance, select Same as Camera to Point.
    • To define a custom OB, for the Placement Distance, select Custom, and then type a Distance Value.