About Creating a Light Source

Lights help you draw the viewer's attention to an element in the work area.

You can use the Light Sources panel to create and manage lights in your scene.

This page discusses:

See Also
Creating and Editing a Light Source

Light Management

In the Light Sources panel, the Light Sources area lets you create and manage different types of lights.

Icon Command Description
Create Light Lets you create a new light.
Spot Light Creates a more realistic conical light.
Point Light Creates a light situated at a given point and emits light isotropically with a more realistic aspect.
Directional Light Creates a light coming from a given direction. It generates constant intensity parallel lighting with a more realistic aspect.
Photometric Light Creates a conical light with a more realistic aspect. The light intensity is measured according to the light direction and it is stored by the manufacturer in an IES (Illuminating Engineering Society) or EULUMDAT file.

To do so, use the Search box to search for a photometric file.

Rectangle Area Light Creates an area light with a rectangular shape.

This light type simulates a rectangular spot light.

Disk Area Light Create an area light that tunes the lighting of each object individually.

This light type simulates a spot light.

Sphere Area Light Create a spherical area light.

This light type simulates a light bulb in a softer and more realistic way than the point light does.

Cylinder Area Light Create a cylindrical area light.

This light type simulates a neon light.

Duplicate Light Duplicates the current light.
Show Representation Hides or shows the light symbol in the 3D area.

Note that this does not deactivate the light.

Delete Deletes the selected light.
N/A Active Select or clear the check box to activate or deactivate the light.

Light Types

You can create physical and nonphysical lights.

The following nonphysical lights are available:

Icon Command Description Use


Directional Light Creates a light that comes from a given direction.

It generates constant intensity parallel lighting.

Simulates a global lighting (the sun light, for example).

In addition to the Light Sources panel, the following physical lights are available from the action bar.

Icon Command Description


Create Physical Spot Light Creates a more realistic conical light.


Create Physical Point Light Creates a light situated at a given point and emits light isotropically with a more realistic aspect.


Create Photometric Light Creates a conical light with a more realistic aspect.

Switch between Light Types

In the Light Sources panel, you can right-click a light symbol in the Light Sources area, and then use the appropriate command to change the light type.



Change to Spot Light


Change to Point Light


Change to Photometric Light


Change to Rectangle Light


Change to Disk Light


Change to Sphere Light


Change to Cylinder Light

Light Symbols

Light symbols help you define the position of a created light.

When you click in the 3D area, you can see the following light symbols:

Spot Point Directional Rectangle Area Disk Area Sphere Area Cylinder Area Photometric

The direction vector represents the privileged direction of illumination of the source for spot and directional lights. It is visualized by an arrow whose origin is the anchoring point of the source.

The anchoring point is the position of the light. It is represented by a small star. When the source is characterized by a direction, the anchoring point coincides with the origin of the arrow. In the case of a spot or punctual light, the anchoring point physically localizes the source. In the case of a directional light, you can use it to define the illumination direction.

Light Manipulation

When you create a light, it is displayed in the 3D area with a source and target point, and handles that help you manipulate the light.

After creating a light, it is displayed in the 3D area:

  • The source point rotates the spot around its target point.
  • The target point rotates the spot around its source point.
  • The upper green handle translates and rotates the spot around its target point.
  • The lower green handle translates and rotates the spot around its source point. It also lets you modify the attenuation end.
  • The green arrows let you modify the angle and the attenuation.

Parameter

In the Light Sources panel, the Parameter area lets you define color and intensity for the physical and nonphysical lights in your scene.

Nonphysical Lights

Option Description
Color Sets a color for the light spread.

Drag the slider, or click the white square to open the color chooser.
Multiplier Sets a multiplier coefficient.

Physical Lights

In the Light Sources panel, the Parameter area lets you define color and intensity for the physical lights in your scene. You can also use light presets.

Option Description
Color Sets a color for the light spread. By default, it is white.

You can choose between two values:

  • Temperature (default)

    Drag the slider, or enter the appropriate value in the box.

  • RGB

    Drag the slider, or click the white square to open the color chooser.
Presets Available only when you select Temperature to define the color.

When you choose a preset in the list, the temperature value of the light is accordingly adjusted.

If you modify the temperature value afterward, the default value in the list is automatically back to Custom (which is the default).
Intensity Sets the intensity of the light in Lumen (lm) or Candela (cd).

The default is Lumen (lm).

Presets

The available presets are based on standard light bulbs.

Low Pressure Sodium Candle High Pressure Sodium Soft White Incandescent Standard Incandescent Halogen Cool White Fluorescent Mercury Vapor

Shape

Nonphysical Lights

In the Light Sources panel, the Shape area lets you define angle and attenuation values for the nonphysical lights in your scene.

Option Description
Angle

Enables you to define the half-angle of the cone, that is the angle between the axis of revolution and the cone edge (for spot light sources only). The angle is a value between 0 and 90 degrees. This means that a value of 90 degrees would generate a light source equivalent to a punctual light source.

Attenuation

  • None: no lighting end, which means that the light energy is constant and infinite.
  • Linear: the light energy decreases linearly with a 1/r ratio ("r" = distance to the light origin) and stops at the attenuation end. For instance, if the energy received at a distance of 10 mm from the light origin is equal to 1/10th of the light energy at the light origin.
Start Ratio

Defines as a ratio the minimum distance for light attenuation. For example:

  • 0 corresponds to an attenuation starting from the center.
  • 0.5 corresponds to an attenuation starting from the middle.
  • 1 corresponds to an attenuation starting from the end, that is a null attenuation.
Angle Ratio

Defines as a fraction of the light angle the angle to the light axis from which the light starts to attenuate. For example:

  • 0 corresponds to an attenuation starting from the axis.
  • 0.5 corresponds to an attenuation starting from the half-angle.
  • 1 corresponds to an attenuation starting from the end, that is a null attenuation.
Tip: You can also position your pointer over one of the side lines, then drag the segment to modify the angle ratio.
Exponent

Simulates the angular attenuation of a spot light intensity from the inner cone to the external cone. By this it means, the exponent parameter controls the slope of the intensity angular attenuation between the external cone defined by the spot angle and the inner cone defined by the angle ratio according to the following formula: cos(angle)Exponent. Its value range is [0-128].

128 corresponds to a fast light decay, 2 corresponds to an almost linear decay.

Physical Lights

In the Light Sources panel, the Shape area lets you define shape dimensions for the physical lights in your scene.

Option Description For
Length/ Width Defines the rectangle dimensions.
Angle Enables you to define the half-angle of the cone, that is the angle between the axis of revolution and the cone edge (for spot light sources only).

The angle is a value between 0 and 90 degrees. This means that a value of 90 degrees would generate a light source equivalent to a punctual light source.

Radius Defines the radius size.

Height Defines the cylinder's height.

Position

In the Light Sources panel, the Position area lets you define some position parameters for the lights in your scene.

Option Description
Position Defines the light position along the X, Y, and Z axes.
Target Defines the point to which the source is directed.
Direction Defines the position of the direction vector along the X, Y, and Z directions.


Displays the light viewpoint.


Adjusts the light when the viewpoint is modified.


Attaches the light to the model or to the viewpoint.

When you move the viewpoint, you move the light along the model.



Positions the light along a perpendicular to the point you click the object in the work area.

To position the light, left-click + move the pointer.



Tunes the specular effect and analyzes surfaces.

To position the light, left-click + move the pointer.



Positions the light direction and manipulates the light along predefined circles that are centered on the light target.

To move the light position step-by-step, press Ctrl + drag the pointer.

Artistic Parameter

The Artistic Parameter area lets you activate realtime shadows.

Option Description
Realtime Shadow Lets you activate or deactivate real-time shadows of lights.

Light Context Menu

This context menu provides several options to view and position the selected light.

To display this context menu, right-click the light in the tree or in the 3D area.

The following options are available:

Icon Command Description
N/A Light object > Hide/Show Representation Hides or shows the light symbol in the 3D area.

This does not deactivate the light.



Light View Displays the light viewpoint.


Update from View Adjusts the light when the viewpoint is modified.


Attach/Detach to View Attaches the light to the model or to the viewpoint.

When you move the viewpoint, you move the light along the model.



Position along Normal Positions the light along a perpendicular to the point you click the object in the work area.

To position the light, left-click + move the pointer.



Position Specular Tunes the specular effect and analyzes surfaces.

To position the light, left-click + move the pointer.


Position Direction Positions the light direction and manipulates the light along predefined circles that are centered on the light target.

To move the light position step-by-step, press Ctrl + drag the pointer.