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title: "VRayIES"
canonical: "https://documentation.chaos.com/space/VMAYA/111739713/VRayIES"
format: markdown
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This page provides information on V-Ray's photometric lights.


## **Overview**

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## **Basic Parameters**

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## **Shadows**

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## **Options**

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## **Sampling**

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## **Decay**

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The Decay parameters determine how the light fades in and out. The Near decay determines how light fades in. The light isn't at its maximum value at its source, but instead gradually increases until it reaches the Near end. The Far decay determines how light fades out. The light isn't at its maximum value at its end, but instead gradually decreases after the Far decay start.

Decay option is useful for creating hotspots or controlling the length of a "God Rays" effect created with Environment Fog.

![image](media://5bf50e6f-375a-4528-a757-41e04695332d)



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> Macro (anchor)



### Example: Near Decay Start

This example shows the variances achieved by changing the Near decay start parameters only.


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### Example: Near Decay End

This example shows the variances achieved by changing the Near decay end parameters only.


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### Example: Far Decay Start

This example shows the variances achieved by changing the Far decay start parameters only.

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 > Macro (anchor)



### Example: Far Decay End

This example shows the variances achieved by changing the Far decay end parameters only.


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### Example: Near and Far Decay

This example shows some artistic lighting results achieved by using both Near and Far decay options.

## **Photon Emission**

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## **UI**

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## **Light Shape**

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> Macro (anchor)



### Example: Light Shape


This example shows how light is affected by the different shapes of the IES Light. Circle and Sphere shapes examples are also compared with different diameters - 1.0 and 10.0.