Types of Lights

Four types of direct lights are available for modifying the appearance and mood of a 3D scene. In addition to the direct lights, Light can also be generated from Indirect light using Global Illumination in the rendering, Emission part/face lighting, and from High Dynamic Range Images used as 3D Environment.

Directional.  Use this type light to cast diffuse, parallel illumination in a single direction, similar to the sun on the earth.  A directional light illuminates all components of the scene toward which it is directed.  Although a directional light is at a fixed distance from objects in the scene, you can change its position and angle by dragging its icon in the scene.  Directional lights are included in all predefined scene templates, although their number and properties may vary.

Spotlight.  A spotlight displays a focused cone of light on a particular area of your scene or part.  As in theater, spotlights in a scene can be used for dramatic emphasis.  You can also use them to represent actual lights in a part, such as headlights on a car. Unlike directional lights, spotlights can be freely positioned without constraints by dragging with the mouse or moving and rotating them with the TriBall tool.  You also have the option of anchoring spotlights to a shape or part.

Point light. Point lights are spherical lights that illuminate evenly in all directions.  For example, you could use point lights to represent lamps in an office layout.  They are positioned in the same manner as spotlights.

Area light.  Area lights simulates the overlay of several light sources over a rectangular area. This provides the natural scattering of light. However, as usual, this method comes with a price: it adds to the render time.

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Modifying a Lights Color & Intensity

In the world of theater, lighting designers insert color filters over lights to create mood-altering effects for a scene.  This offers the same flexibility.

You can also increase a light’s intensity to make it appear brighter.  Alternately, you can assign negative intensities to a light to create areas where light is removed from the scene.

You can change the color and intensity of directional lights, spotlights, point lights, area lights (and Emission values).  You can use either the Light Wizard or the Light Properties sheets, which are accessed by right-clicking the light and then selecting the desired option from its pop-up menu.  You can also select Shape Properties from the Format menu to access the Light Properties (or from the Tools Fluent Ribbon Bar).

To Modify A Light Source's Color And Intensity Using The Light Properties Options:

1. Display the lights in the scene by selecting Show Lights from the View menu (or from the Visualization Fluent Ribbon Bar).
2. Select a light source, either by clicking its icon in the scene or in the Scene Browser. The light icon is highlighted in the scene, indicating its selection.  Also displayed is a line or cone that indicates how the light strikes the part.
3. Right-click the light source and then choose Light Properties from the resulting pop-up menu.
4. From the Light Properties sheet, choose the Light tab.
5. Select an alternate color, if desired, by clicking on the desired color in the palette.
6. If desired, edit the value in the Intensity field. To make an area darker, enter a negative number in the Intensity field.
7. Choose OK to return to the scene and view the results of the edits.

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Modifying Light Shadow Settings

Advanced settings are offered for refining the appearance of shadows, allowing you to adjust the softness and resolution of the shadows cast by each light source. Advanced shadow settings are available for directional lights, spotlights, and point lights with the Cast Shadows option enabled.

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To Adjust Advanced Shadows Settings:

1. If necessary, choose the Select tool.
2. Right-click a light source and choose Light Properties from the resulting pop-up menu.
3. Choose the Light properties tab.
4. If necessary, select the Cast Shadows option.
5. Select Advanced Settings.
6. On the Advanced Shadow Setting dialog box, select a method for computing advanced shadow settings.
   
   Shadow Buffer.  Select this option to create shadows by generating a bitmap image of the shadow in a buffer associated with the light source.  This technique produces soft shadows that are appropriate for some lighting conditions.  This is only available in the Legacy Raytracing Engine mode. If this is set and you use the Advance Rendering Engine, it will default to Raytraced shadows. This option must be selected to access the following options:
   - Edge Softness.  Enter a value between 1 and 10 in this field to specify softness of the shadow’s edge.  A value of 1 produces the most sharply defined shadow; a value of 10, the softest and most diffuse shadows.  Edge softness characteristics are only apparent if the Antialiasing option is selected on the Rendering properties sheet.
   - Shadow Resolution.  Increasing this value enlarges the buffer for computing shadows and improves the quality of the shadow edges.  Higher resolution requires greater memory.  The resolution range is 20 to 1000.
   - Sampling rate.  Enter a value in this field to specify the number of samples to be taken from the shadow buffer during rendering.  The default value of 16 produces adequate shadows for most images.  Increasing the sampling rate produces smoother shadows at the expense of rendering time.  The sampling rate is only useful if you choose Antialiasing in the Rendering properties sheet.
   - Bias percentage.  Enter a bias percentage value in this field to specify the distance between a shadow’s edge and the object that casts it.  Bias is specified as a percentage of the scene’s size.  Decrease the value to move the shadow’s edge closer to the object; increase the value to move the shadow’s edge away from the object.  If the shadow appears streaked or distorted, or appears to shadow itself, the bias percentage value is set too low.  If the value is too high, shadows may display gaps where two objects touch.
   
   Ray traced.  Select this option to produce shadows by tracing the rays of light between a light source and the objects that cast shadows.  This technique produces sharp-edged shadows that are more accurate and precise than those from buffering.  Ray tracing also creates a transparency effect.  However, if the scene lighting requires soft shadows, use the Shadow Buffer option.  If you use ray tracing, expect a delay in processing.
   
   Soft Ray traced.  Soft Ray-traced shadows eliminate the sharpness of standard Ray-traced shadows by casting many rays in slightly varying directions—then averaging the result.  Using this setting can slow down the realistic rendering based on the settings defined.
   - Radius.  The radius is used to determine the maximum variation in the rays fired when calculating a shadow percentage.  You might think of this as the ‘size’ of a light bulb.  A larger radius will give more variation resulting in softer (and more noisy) shadows.  A radius of zero is equivalent to standard ray-traced shadows.
   - Samples.  The number of rays fired in varying directions then averaged to determine a shadow percentage.  You may think of this as a quality setting.  Higher numbers yield smoother results at the expense of performance.  Low numbers give noisy results, particularly when combined with a larger radius.

7. Choose OK to return to the scene

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Modifying a Lights Attenuation

Attenuation refers to the way light falls off with distance.  By modifying attenuation, you can create realistic light that dims as it travels away from its source.  You can modify the attenuation properties of spotlights and point lights, but not of directional lights.

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To Modify The Attenuation Properties Of A Point Light Or Spotlight:

1. If necessary, choose the Select tool.
2. Right-click a spotlight, point light, or area light and choose Light Properties from the resulting pop-up menu.
3. Select the Attenuation tab.
4. Check the Attenuation On option to access its properties options.
5. Enter the desired value in the Minimum and Maximum distance fields. The Minimum setting specifies the distance from the light at which falloff begins; the Maximum setting specifies the distance from the light at which illumination falls off to nothing.
6. Select a falloff type from the following options:
   Linear.  Choose this option for brightness to decrease as a linear function of distance.  Light falls off at a constant, unchanging rate.
   Smooth.  Choose this option for smooth, linear falloff in the form of an "S" curve.
   Inverse Distance.  Choose this option for brightness to decrease in inverse proportion to distance.  Light falls off quickly and provides a realistic appearance that is easier to control than the inverse distance squared option.
   Inverse Distance Squared.  This is the falloff type for real lights.  Choose this option for brightness to decrease in inverse proportion to the square of the distance.  Light falls off very quickly, but it can be hard to control if your scene has wide variations of brightness.  To modify the scene’s brightness, edit the Exposure properties.
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7. Choose OK to close the dialog box and return to the scene.

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Spotlight Advanced Settings

Certain light modifications are only available with spotlights, such as adding gels and editing cone angles, falloff angles, and concentrations.

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Adding A Gel To A Spotlight

A gel is a filter that is placed over a spotlight to alter its effect on a scene.  You can use any texture or bitmap image as a gel.  You can use a texture as a color filter for the light to produce a stained-glass effect or use the texture’s intensity to dim the light without coloring to produce mottled shade or venetian-blind effects.

To add a gel to a spotlight:

1. If necessary, choose the Select tool.
2. Right-click the spotlight and choose Light Properties from the resulting pop-up menu.
3. Select the Gel tab on the Spot Light IntelliShape dialog box.
4. Select the gel type from the following options:
   ‍None.  Use this option if no gel is desired.  (Default)
   ‍Shadow mask.  Use this option to create a shadowing effect.
   Color filter.  Use this option to create a colored gel.
5. Select the desired image file for the gel.
   Gels are images.  To select an image file for a gel, choose Browse and locate and open the Images folder, which contains image files suitable for gels.
   Double-click to select the desired image file and return to the Gel properties sheet.  Note that the name of the gel image now appears in the Image File field.
6. Specify the gel shape by selecting either the Round or Square option.
7. Choose OK to close the dialog box and return to the scene.

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Modifying Spotlight Cone/Falloff Angles And Concentrations

Spotlights have several settings for defining the cones of illumination they generate.  These settings are unique to spotlights, and are not available with point lights or directional lights.

To modify the cone angle, falloff angle, and concentration of a spotlight:

1. If necessary, choose the Select tool.
2. Right-click a spotlight and choose Light Properties from the resulting pop-up menu.
3. Choose the Light tab on the Spot Light IntelliShape dialog box.
4. Edit the following settings, as desired.
   Cone angle.  In this field, enter the desired value for the angle of the spotlight’s cone of illumination
   Falloff angle.  Enter a value in this field to specify the falloff angle between the outer edge of the light cone and the outer edge of the falloff cone.  A value of 0 creates a razor-sharp spotlight; a value greater than 0 creates a space between the two cones containing light that diminishes in intensity as it approaches the edge of the falloff cone and results in a softer edge.
   Concentration.  Enter a value in this field to define the concentration or brightness of the beam about its central direction.  If you enter a value of 0, the light is equally bright across its cone.  If you enter a value of 30, the spotlight has a very small bright spot that falls off rapidly toward its falloff cone.
5. Choose OK to close the dialog box and return to the scene.

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Adding Glow And Volume To Your Lights

Adding Glow

Lights typically are not rendered—only the result of the light they emit.  But, when glow is enabled, lights are rendered as bright circles in the scene.  The effect is not volumetric (shadowing of the glow is not considered).  

Intensity.  The brightness of the glowing region.  This number is combined with the light intensity.

Size.  The diameter of the glowing region.  The glow will drop off quickly outside of this diameter.

Color.  The color of the glowing region.  The glow may be a different color than the light itself- as if interacting with a colored environment.

Adding Volume Lighting

Lights typically are not rendered—only the result of the light they emit.  But, when Volume Lighting is enabled, spot-light cones are rendered as bright regions in the scene.  The effect is volumetric (objects may shadow the spotlight cone).

• Density.  The brightness of the glowing region.  
• Resolution.  The accuracy used when calculating shadowing inside the glowing region.  Higher numbers will give more accurate results at the expense of performance.
• Samples.  The results may be blurred to give a softer effect.  The number of samples determines the quality of this blur.
• Blur.  The results may be blurred to give a softer effect.  The blur amount controls the fuzziness of the blur.
• Color.  The color of the glowing region.  The glow may be a different color than the light- as if interacting with a colored environment.
• Turbulence.  A smoky effect may be generated using turbulence.  This uses a pseudo-random noise to attenuate the result.
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Global Illumination (GI) Settings

Each light may be individually configured for consideration in the overall global illumination calculations.

• Lighting Mode.
  Direct.  Only direct light is calculated.  Direct light is the brightening of surfaces in direct view of the light.  This is as opposed to indirect light, which reaches a surface by reflection or refraction.
  Indirect.  Only indirect light is calculated.  Indirect light is light that reaches a surface by reflection or refraction.  This is as opposed to direct light, which is the result of being in the direct view of the light.  Indirect lighting is what gives rise to caustics and radiosity.
  Direct & Indirect.  Both Direct and Indirect lighting are considered. Direct light is the brightening of surfaces in direct view of the light.  Indirect light is light that reaches a surface by reflection or refraction.  Indirect lighting is what gives rise to caustics and radiosity.‍
• Global.  This setting causes the light to obey the global GI settings.  These global settings are specified in the Advanced rendering options.  This allows all lights to be adjusted simultaneously with low effort.‍
• Independent.  This setting causes the light to have unique GI settings.  These settings will be used instead of the global settings specified in the advanced rendering options.‍
• Caustics.  Caustics are the effect of indirect light being refracted into patterns that are visible when shined onto adjacent geometry.  A typical example would be the bright spot in the center of the shadow of a semi transparent sphere.  The bright spot is caused by the focusing of light as it is refracted through the sphere.‍
• Radiosity.  Radiosity is the effect of indirect light that is reflected onto adjacent geometry.  A typical example is the color bleeding effect of a red sphere placed next to a white wall.  The wall will appear slightly pink near the sphere.‍
• Caustic & Radiosity Settings.
  Power.  The intensity of the effect.  Higher values will result in a brighter effect.
  Count.  The number of photons fired from the light source.  The photons are the samples used to approximate the lighting effect.  Higher values give more accurate results at the expense of performance.
  Radius.  The radius in which to search for neighboring photon hits.   This is used in conjunction with the Blur setting.  The hits that are found are averaged together to smooth the resulting effect.
  Blur.  The maximum number of neighboring photon hits to consider.  This is used in conjunction with the Radius setting.  The hits that are found are averaged together to smooth the resulting effect.
  Depth.  The maximum number of bounces or penetrations that photons may undergo before expiring.  Higher values result in more accurate results at the expense of performance.

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Point Light Advanced Settings

Certain light modifications are only available with point lights, such as adding glow and global illumination.

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Adding Glow To Your Lights

Adding Glow

Lights typically are not rendered—only the result of the light they emit.  But, when glow is enabled, lights are rendered as bright circles in the scene.  The effect is not volumetric (shadowing of the glow is not considered).  

Intensity.  The brightness of the glowing region.  This number is combined with the light intensity.

Size.  The diameter of the glowing region.  The glow will drop off quickly outside of this diameter.

Color.  The color of the glowing region.  The glow may be a different color than the light itself- as if interacting with a colored environment.

Global Illumination (GI) Settings

Each light may be individually configured for consideration in the overall global illumination calculations.

• Lighting Mode.
  Direct.  Only direct light is calculated.  Direct light is the brightening of surfaces in direct view of the light.  This is as opposed to indirect light, which reaches a surface by reflection or refraction.
  Indirect.  Only indirect light is calculated.  Indirect light is light that reaches a surface by reflection or refraction.  This is as opposed to direct light, which is the result of being in the direct view of the light.  Indirect lighting is what gives rise to caustics and radiosity.
  Direct & Indirect.  Both Direct and Indirect lighting are considered. Direct light is the brightening of surfaces in direct view of the light.  Indirect light is light that reaches a surface by reflection or refraction.  Indirect lighting is what gives rise to caustics and radiosity.‍
• Global.  This setting causes the light to obey the global GI settings.  These global settings are specified in the Advanced rendering options.  This allows all lights to be adjusted simultaneously with low effort.‍
• Independent.  This setting causes the light to have unique GI settings.  These settings will be used instead of the global settings specified in the advanced rendering options.‍
• Caustics.  Caustics are the effect of indirect light being refracted into patterns that are visible when shined onto adjacent geometry.  A typical example would be the bright spot in the center of the shadow of a semi transparent sphere.  The bright spot is caused by the focusing of light as it is refracted through the sphere.‍
• Radiosity.  Radiosity is the effect of indirect light that is reflected onto adjacent geometry.  A typical example is the color bleeding effect of a red sphere placed next to a white wall.  The wall will appear slightly pink near the sphere.‍
• Caustic & Radiosity Settings.
  Power.  The intensity of the effect.  Higher values will result in a brighter effect.
  Count.  The number of photons fired from the light source.  The photons are the samples used to approximate the lighting effect.  Higher values give more accurate results at the expense of performance.
  Radius.  The radius in which to search for neighboring photon hits.   This is used in conjunction with the Blur setting.  The hits that are found are averaged together to smooth the resulting effect.
  Blur.  The maximum number of neighboring photon hits to consider.  This is used in conjunction with the Radius setting.  The hits that are found are averaged together to smooth the resulting effect.
  Depth.  The maximum number of bounces or penetrations that photons may undergo before expiring.  Higher values result in more accurate results at the expense of performance.

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Area Light Advanced Settings

Certain light modifications are only available with area lights, such as adding global illumination.

Global Illumination (GI) Settings

Each light may be individually configured for consideration in the overall global illumination calculations.

• Lighting Mode.
  Direct.  Only direct light is calculated.  Direct light is the brightening of surfaces in direct view of the light.  This is as opposed to indirect light, which reaches a surface by reflection or refraction.
  Indirect.  Only indirect light is calculated.  Indirect light is light that reaches a surface by reflection or refraction.  This is as opposed to direct light, which is the result of being in the direct view of the light.  Indirect lighting is what gives rise to caustics and radiosity.
  Direct & Indirect.  Both Direct and Indirect lighting are considered. Direct light is the brightening of surfaces in direct view of the light.  Indirect light is light that reaches a surface by reflection or refraction.  Indirect lighting is what gives rise to caustics and radiosity.‍
• Global.  This setting causes the light to obey the global GI settings.  These global settings are specified in the Advanced rendering options.  This allows all lights to be adjusted simultaneously with low effort.‍
• Independent.  This setting causes the light to have unique GI settings.  These settings will be used instead of the global settings specified in the advanced rendering options.‍
• Caustics.  Caustics are the effect of indirect light being refracted into patterns that are visible when shined onto adjacent geometry.  A typical example would be the bright spot in the center of the shadow of a semi transparent sphere.  The bright spot is caused by the focusing of light as it is refracted through the sphere.‍
• Radiosity.  Radiosity is the effect of indirect light that is reflected onto adjacent geometry.  A typical example is the color bleeding effect of a red sphere placed next to a white wall.  The wall will appear slightly pink near the sphere.‍
• Caustic & Radiosity Settings.
  Power.  The intensity of the effect.  Higher values will result in a brighter effect.
  Count.  The number of photons fired from the light source.  The photons are the samples used to approximate the lighting effect.  Higher values give more accurate results at the expense of performance.
  Radius.  The radius in which to search for neighboring photon hits.   This is used in conjunction with the Blur setting.  The hits that are found are averaged together to smooth the resulting effect.
  Blur.  The maximum number of neighboring photon hits to consider.  This is used in conjunction with the Radius setting.  The hits that are found are averaged together to smooth the resulting effect.
  Depth.  The maximum number of bounces or penetrations that photons may undergo before expiring.  Higher values result in more accurate results at the expense of performance.