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Note: When a PlaneDisc, or Sphere light is visible in the rendering, aliasing at the edges of the light source can occur. Lens Effects such as the Bloom Effect (as used in the example images below) and Glare Effect are one way to hide the aliasing, while another is the use of a VraySoftBox map. For information on the cause of the aliasing and solutions for it, see Notes  Notes below.


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Plane
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Plane lights rendering (with slight Bloom Effect)

 

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Res – Specifies the resolution at which the texture is resampled for importance sampling.

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This rollout is only available when the Type is set to Plane or Disc.

Directional – By default, the light from the Plane or Disc light is spread out equally in all directions on the side in which the light points. When this parameter is increased, the spread is narrowed which makes the light more directional. A value of 0 (default) the light shines in all directions around the light source. A value of 0.5 pushes the light cone to a 45-degree angle, and a value of 1.0 (maximum) makes a 90-degree light cone.

 

Image RemovedPlane light with Directional = 0, 0.5, 1.0
Preview = Always 

 

 

Preview – Previews the effects of the Directional parameter in the viewport.

Always – The preview is always displayed. 
Selected – The preview is displayed only when the light is selected. 
Never – The preview is never displayed.

 

Preview texmap – If a texture is used to drive the light, enabling this will show the texture in the viewport. This option will be grayed out if your 3DS Max viewport is configured to use Nitrous viewport driver. To enable, switch to the direct3D viewport.

 

 

 

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Radius = 0.5Units set to Luminous power (lm)

 

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Radius = 1.0Units set to Luminous power (lm)

 

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Radius = 2.0Units set to Luminous power (lm)

 

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Example: Light Size and Intensity

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Radius = 0.5Units = Default (image)

 

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Radius = 1.0; Units = Default (image)

 

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Radius = 2.0; Units = Default (image)

 

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Parameters -  Rectangle/Disc Light Rollout

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This rollout is only available when the Type is set to Plane or Disc.

Directional – By default, the light from the Plane or Disc light is spread out equally in all directions on the side in which the light points. As this parameter is increased toward a value 0f 1.0, the spread narrows, making the light more directional. A value of 0 (default) the light shines in all directions around the light source. A value of 0.5 pushes the light cone to a 45-degree angle, and a value of 1.0 (maximum) makes a 90-degree light cone. For more information, see the Directional Spread example below.

Preview – Allows the light's spread angle to be seen as a wireframe in the viewport, as it is set by the light's Directional parameter.

Always – The preview is always displayed. 
Selected – The preview is displayed only when the light is selected. 
Never – The preview is never displayed.

Preview texmap – If a texture is used to drive the light, enabling this will show the texture in the viewport. This option will be grayed out if your 3DS Max viewport is configured to use Nitrous viewport driver. To enable, switch to the direct3D viewport.


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Example: Directional Spread

 

The Directional parameter controls the spread of the Plane or Disc light. A value of 0 produces the maximum spread of light in all directions as seen below left, while a value of 1 creates a narrow 90-degree cone of light as seen below right.

 

Image AddedPlane light with Directional = 0, 0.5, 1.0
Preview = Always

 

 

The following example shows the effect of the Directional parameter. Note that the plane light itself appears to turn black as the value gets closer to 1.0. This is due to the simplified directional distribution. The light is forced only in the forward direction, so the plane appears dark when viewing it from the side. This phenomenon does not occur with real-world lights because they exhibit more complex directional distribution.

 

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Image AddedDirectional = 0.6


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Image AddedDirectional = 0.8


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Image AddedDirectional = 1.0


 

 

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Parameters -  Options Rollout

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Skylight portal – When enabled, the light behaves as a portal or conduit for the environment behind it. As an example, this option is appropriate for an interior daytime scene, where a Plane light source could be placed in a window opening and directed toward the inside of a room. If the Skylight portal option is enabled for such a light, the light and color from the scene outside the window (including the environment map and any rendered objects) flows directly through the window opening and into the room. While an interior daytime scene is often sufficiently lit by a bright environment and GI alone, the Skylight portal option can be used to augment or brighten such lighting. With this option, the light takes its intensity and color from the environment behind it rather than from the Color and Multiplier parameters. For more information, see  The Skylight, Self-Illuminated Panels, and VRayLights example example below.

Simple – Available only if the Skylight portal option is enabled. When this option is enabled, the portal will only use colors from the environment map and not from any scene objects behind the portal. When this option is disabled, the portal light takes its color from both the environment map and objects behind the light source. If this option is disabled, the light traces additional rays to render the objects, which might slow down the rendering. Enabling this option makes the rendering of portal lights faster.

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The VRayLight in the viewport.

 

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Double-sided is disabled

 

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Double-sided is enabled

 

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Example: No Decay vs. Real-World Light Behavior


The following images demonstrate the use of the No decay setting on the Options rollout. In the real world, light attenuates with the inverse square of the distance from the light to the shaded surface. The settings for the light source are the same for both images with the exception of the No decay setting:

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No decay is enabled

 

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Example: Skylight, Self-Illuminated Panels, and VRayLights

 

Here is an example of a simple room where the light comes from the environment. The scene was rendered in several different ways with GI enabled and using Progressive mode to achieve the same quality level:

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  • With just a plane light with simple Skylight environment, with Irradiance map as the primary GI engineenabled allowing in light from the environment behind it
  • With a 3ds Max Plane object at the window that has a VRayMtl assigned to it with the Self-Illumination color set to white and the GI option enabled, with Irradiance map as the primary GI engine
  • With a Plane light at the window with Irradiance map as the primary GI engineWith just a Skylight environment, with Brute Force window

In all cases, Brute Force was used as the primary GI engine

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In all cases, and Light cache was used as a secondary GI engine. The environment, the self-illuminated panel, and the Plane light all have the exact same color and multiplier.

 

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Skylight only, Irradiance map
Render Time: 3m 251m 37.9s 8s 

 

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Self-illuminated panel at the window, Irradiance map
Render Time: 3m 221m 46.6s 

 

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Plane light, Irradiance mapImage Added
Plane light only
Render Time 2m 390m 18.2s 

 

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Skylight, Brute Force
Render Time: 30m 17.4s

 

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As you can see, all methods produce a similar almost exactly the same light distribution, but there are differences in render times and quality.

In the first two cases, we rely on the Irradiance map GI to capture the lighting coming from the window. The result is very similar, as well as the rendering times. Since Irradiance map is a blurry method, the shadows come out a little blurred. Although we can reduce the blurring by using higher Irradiance map settings, this will cost us additional render time.

In the third case, the VRayLight produces crisp shadows, and the rendering time is reduced. This is because the Irradiance map was calculated much faster – in the previous two cases, it had to trace a lot of rays to sample the window accurately.

In the fourth case, we used brute force GI instead of the irradiance map. This produces sharp shadows too, since the brute force GI is a non-blurry GI method. However, render time has increased quite a lot.

to achieve the same quality level between using a light or a self-illuminated plane or a skylight. In this example, using a VRayLight produces produced the best result in the shortest a dramatically shorter time. However, if you need to have many lights, this method can may become quite slow because every single light needs to be sampled.

 

 

 

Parameters -  Sampling Rollout

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Subdivs – This parameter is disabled by default since most users will not need local control of subdivs, however, this parameter controls the number of samples V-Ray takes to compute lighting locally for this light. Lower values create more noise , but render faster. Higher values produce smoother results but take more time to render.

To activate this parameter and specify a value, use the Use local subdivs parameter under the V-Ray tab > Global DMC Sampler rollout in the Render Setup window. Note that the actual number of samples also depends on the Global DMC Settings. By default, this parameter is controlled by the Min samples parameter in the Advanced user mode of the Global DMC rollout.

Shadow bias – This value moves the shadow toward or away from the shadow-casting object (or objects). Higher values move the shadow toward the object(s) while lower values move it away. If this value is too extreme, shadows can "leak" through places they shouldn't or "detach" from an object. Other effects from extreme values include moire Moire patterns, out-of-place dark areas on surfaces, and shadows not appearing at all in the rendering.

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  • When using texture-mapped Plane lights, it is best to have GI enabled. This allows V-Ray to use combined direct and indirect sampling for the light, which greatly reduces the noise for surfaces close to the light.

  • The effect of all textured V-Ray lights can be shown through the Nitrous preview in the viewport.
  • When the Store with irradiance map option is check on any V-Ray Light it is then no longer treated as a direct light source and will not be available within the Light Select Render Element.
  • When an Area light is visible in a rendering, the edges of the light source can appear to be aliased. This happens because the light source color is usually very, very bright, far beyond the range of what an ordinary monitor can display, and antialiasing involves changing the colors of pixels at the edges of objects to a color midway between two other colors. When V-Ray applies antialiasing to a light source's edges, any colors midway between the light color and surrounding object colors are still very bright, beyond what a monitor can display, and the pixels that are supposed to provide a smooth transition from the light source to the surrounding objects appear to be the same color as the light source. As a result, there appears to be no antialiasing at all around the light source. To solve this problem, use a VRaySoftbox texture on the light source to cause its brightness to reduce at the edges, or use Lens Effects to soften and blur the aliased edges of the lights after rendering.