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  "identifier" : "/documentation/SceneKit/SCNLight/iesProfileURL",
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# iesProfileURL

The URL for a file that contains photometry data describing the intended appearance of the light.

```
var iesProfileURL: URL? { get set }
```

## Discussion

A photometric light source is one whose shape, direction, and intensity of illumination is determined by a file in the IES format, containing physical measurements of a light source. Many manufacturers of real-world light fixtures publish such files describing the lighting characteristics of their products. This photometry data measures the light web surrounding a light source—measurements of the light’s intensity in all directions around the source.

By default, this property’s value is `nil`. After setting this property to a URL that references a valid IES profile, you must set the light’s type property to [`IES`](/documentation/SceneKit/SCNLight/LightType/IES) to load that file and apply its effect.

---

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