# Volumetric Clouds Volume Override reference

The Volumetric Clouds Volume Override lets you configure how HDRP renders volumetric clouds.

Refer to [Create realistic clouds (volumetric clouds)](create-realistic-clouds-volumetric-clouds.md) for more information.

## Properties

### General

| **Property** | **Description**                                       |
| ------------ | ----------------------------------------------------- |
| **State**        | When set to **Enabled**, HDRP renders volumetric clouds. |

### Shape

| **Property**                      | **Description**                                              |
| --------------------------------- | ------------------------------------------------------------ |
| **Cloud Control**                 | Specifies the mode to control volumetric cloud properties. The options are:<br/>&#8226; **Simple**: Uses sliders and input fields to customize volumetric cloud shape properties. This mode generates a cloud map from the various properties and uses HDRP's internal cloud lookup table.<br/>&#8226; **Advanced**: Uses separate Textures to specify each cloud type and their coverage. This mode generates a cloud map from the various Textures and uses HDRP's internal cloud lookup table.<br/>&#8226; **Manual**: Uses the cloud map and lookup table you supply to render the clouds. For more information on the cloud map and cloud lookup table, see [Cloud map and cloud lookup table](#cloud-map-and-cloud-lookup-table). |
| - **Cloud Preset**                | Specifies the preset to apply to the **Simple** mode properties. The options are: <br/>&#8226; **Sparse**: Smaller clouds that are spread apart.<br/>&#8226; **Cloudy**: Medium-sized clouds that partially cover the sky.<br/>&#8226; **Overcast**: A light layer of cloud that covers the entire sky. Some areas are less dense and let more light through, whereas other areas are more dense and appear darker.<br/>&#8226; **Storm Clouds**: Large dark clouds that cover most of the sky.<br/>&#8226; **Custom**: Exposes properties that control the shape of the clouds. <br/><br/>This property only appears if you set **Cloud Control** to **Simple**. |
| - **Density Curve**        |  Controls the density (Y axis) of the volumetric clouds as a function of the height (X Axis) inside the cloud volume. <br/><br/>This property only appears if you set **Cloud Control** to **Simple**.|
| - **Erosion Curve**        |  Controls the erosion (Y axis) of the volumetric clouds as a function of the height (X Axis) inside the cloud volume. <br/><br/>This property only appears if you set **Cloud Control** to **Simple**.|
| - **Ambient Occlusion Curve**        |  Controls the ambient occlusion (Y axis) of the volumetric clouds as a function of the height (X Axis) inside the cloud volume. <br/><br/>This property only appears if you set **Cloud Control** to **Simple**.|
| - **Cumulus Map**                 | Specifies a Texture that defines the distribution of clouds in the lower layer. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced**. |
| - **Cumulus Map Multiplier**      | The multiplier for the clouds specified in the **Cumulus Map**. A value of **0** completely hides the cumulus clouds. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced**. |
| - **Alto Stratus Map**            | Specifies a Texture that defines the distribution of clouds in the higher layer. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced**. |
| - **Alto Stratus Map Multiplier** | The multiplier for the clouds specified in the **Alto Stratus Map**. A value of **0** completely hides the alto stratus clouds. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced**. |
| - **Cumulonimbus Map**            | Specifies a Texture that defines the distribution of anvil shaped cumulonimbus clouds. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced**. |
| - **Cumulonimbus Map Multiplier** | The multiplier for the clouds specified in the **Cumulonimbus Map**. A value of **0** completely hides the cumulonimbus clouds. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced**. |
| - **Rain Map**                    | Specifies a Texture that defines the distribution of rain in the clouds. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced**. |
| - **Cloud Map Resolution**        | Specifies the resolution for the internal Texture HDRP uses for the cloud map. A lower resolution produces better performance, but less precise cloud type transitions. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced**. |
| - **Cloud Map**                   | Specifies the cloud map to use for the volumetric clouds. For information on the format of this Texture, see [Cloud map and cloud lookup table](#cloud-map-and-cloud-lookup-table). <br/><br/>This property only appears if you set **Cloud Control** to **Custom**. |
| - **Cloud LUT**                   | Specifies the lookup table for the clouds. For information on the format of this Texture, see [Cloud map and cloud lookup table](#cloud-map-and-cloud-lookup-table).  <br/><br/>This property only appears if you set **Cloud Control** to **Custom**. |
| - **Cloud Map Tiling**            | The **X** and **Y** UV tile rate for one or more cloud map Textures. HDRP uses the **X** and **Y** values to tile the clouds across the sky.<br/>If **Cloud Control** is set to **Advanced**, this affects **Cumulus Map**, **Alto Stratus Map**, **Cumulonimbus Map**, and **Rain Map**.<br/>If **Cloud Control** is set to **Custom**, this affects the Texture assigned to the **Cloud Map** property.<br/><br/>This property only appears if you set **Cloud Control** to **Advanced** or **Custom**. |
| - **Cloud Map Offset**            | The **X** and **Y** UV offset for one or more cloud map Textures. HDRP uses the **X** and **Y** values to offset the clouds across the sky.<br/>If **Cloud Control** is set to **Advanced**, this affects **Cumulus Map**, **Alto Stratus Map**, **Cumulonimbus Map**, and **Rain Map**.<br/>If **Cloud Control** is set to **Custom**, this affects the Texture assigned to the **Cloud Map** property.<br/><br/>This property only appears if you set **Cloud Control** to **Advanced** or **Custom**, or if you set it to **Simple** and then set **Cloud Preset** to **Custom**. |
| - **Density Multiplier**          | The global density of the volumetric clouds. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced** or **Custom**, or if you set it to **Simple** and then set **Cloud Preset** to **Custom**. |
| - **Shape Factor**                | Controls the amount of shaping to apply to the cloud volume. A higher value produces less cloud coverage and smaller clouds. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced** or **Custom**, or if you set it to **Simple** and then set **Cloud Preset** to **Custom**. |
| - **Shape Scale**                 | Controls the size of the noise HDRP uses in the shaping stage to generate the general cloud shapes. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced** or **Custom**, or if you set it to **Simple** and then set **Cloud Preset** to **Custom**. |
| - **Shape Offset X**              | Controls the offset (world X-axis) applied when evaluating the larger noise passing through the cloud coverage. The values "0", "-1" and "1" will give the same result. |
| - **Shape Offset Y**              | Controls the offset (world Y-axis) applied when evaluating the larger noise passing through the cloud coverage. The values "0", "-1" and "1" will give the same result. |
| - **Shape Offset Z**              | Controls the offset (world Z-axis) applied when evaluating the larger noise passing through the cloud coverage. The values "0", "-1" and "1" will give the same result. |
| - **Erosion Factor**              | Controls the amount of erosion to apply on the edge of the clouds. A higher value erodes clouds more significantly. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced** or **Custom**, or if you set it to **Simple** and then set **Cloud Preset** to **Custom**. |
| - **Erosion Scale**               | Controls the size of the noise HDRP uses in the erosion stage to add local details to the cloud edges. <br/><br/>This property only appears if you set **Cloud Control** to **Advanced** or **Custom**, or if you set it to **Simple** and then set **Cloud Preset** to **Custom**. |
| **Bottom Altitude**               | Controls the altitude of the bottom of the volumetric clouds volume in meters.|
| **Altitude Range**                | Controls the size of the volumetric clouds volume in meters. |
| **Fade In Mode**                  | Controls the mode in which the clouds fade in when close to the camera's near plane.|
| **Fade In Start**                 | Controls the minimal distance at which clouds start appearing.|
| **Fade In Distance**              | Controls the distance that it takes for the clouds to reach their complete density.|

### Wind

| **Property**                     | **Description**                                              |
| -------------------------------- | ------------------------------------------------------------ |
| **Global Horizontal Wind Speed**  | Sets the global horizontal wind speed in kilometers per hour.<br />This value can be relative to the **Global Wind Speed** defined in the **Visual Environment**. |
| - **Orientation**                | Controls the orientation of the wind relative to the world-space direction x-axis.<br />This value can be relative to the **Global Wind Orientation** defined in the **Visual Environment**. |
| - **Cloud Map Speed Multiplier** | The multiplier to apply to the speed of the cloud map.       |
| - **Shape Speed Multiplier**     | The multiplier to apply to the speed of larger cloud shapes. |
| - **Erosion Speed Multiplier**   | The multiplier to apply to the speed of erosion cloud shapes. |
| **Vertical Shape Wind Speed**    | Controls the vertical wind speed of the larger cloud shapes. |
| **Vertical Erosion Wind Speed**  | Controls the vertical wind speed of the erosion cloud shapes. |

### Quality

| **Property**                     | **Description**                                              |
| -------------------------------- | ------------------------------------------------------------ |
| **Temporal Accumulation Factor** | The amount of temporal accumulation to apply to the clouds. Temporal accumulation increases the visual quality of clouds by decreasing the noise. A higher value produces better quality clouds, but can create [ghosting](Glossary.md#ghosting). |
| **Ghosting Reduction**           | When you enable this property, HDRP removes the ghosting caused by temporal accumulation. This effect might cause a flickering effect when the **Temporal Accumulation Factor** value is low. |
| **Num Primary Steps**            | The number of steps to use to evaluate the clouds' transmittance. Higher values linearly increase the resource intensity of the effect. |
| **Num Light Steps**              | The number of steps to use to evaluate the clouds' lighting. Higher values exponent increase the resource intensity of the effect. |

### Lighting

| **Property**                   | **Description**                                              |
| ------------------------------ | ------------------------------------------------------------ |
| **Ambient Light Probe Dimmer** | Controls the influence of light probes on the cloud volume. A lower value suppresses the ambient light and produces darker clouds overall. |
| **Sun Light Dimmer**           | Controls the influence of the sun light on the cloud volume. A lower value suppresses the sun light and produces darker clouds overall. |
| **Erosion Occlusion**          | Controls how much Erosion Factor is taken into account when computing ambient occlusion. The Erosion Factor parameter is editable in the custom preset, Advanced and Manual Modes. |
| **Scattering Tint**            | The color to tint the clouds.                                |
| **Powder Effect Intensity**    | Controls the amount of local scattering in the clouds. When clouds have a lot of local details due to erosion, a value of **1** provides a more powdery aspect. |
| **Multi Scattering**           | Controls the amount of multi-scattering inside the cloud. Higher values make lighting look more diffuse within the cloud. |

### Shadows

| **Property**                     | **Description**                                              |
| -------------------------------- | ------------------------------------------------------------ |
| **Shadows**                      | When enabled, HDRP evaluates the Volumetric Clouds' shadows. The Volumetric Clouds shadow is rendered independently of the shadow map toggle of the directional [Light](Light-Component.md). |
| - **Shadow Resolution**          | Specifies the resolution of the volumetric clouds shadow map. |
| - **Shadow Distance**            | The size of the area to render volumetric cloud shadows around the camera. |
| - **Shadow Opacity**             | The opacity of the volumetric cloud shadows.                 |
| - **Shadow Opacity Fallback**    | Controls the shadow opacity when outside the area covered by the volumetric clouds shadow. |

### Cloud map and cloud lookup table

The **Cloud Map** and **Clout LUT** Textures define the shape and look of volumetric clouds. Both of these Textures are [channel-packed](Glossary.md#channel-packing) where each channel contains a separate grayscale Texture with a specific purpose. These two maps are not trivial to author, so it is best to only set **Cloud Control** to **Manual** if your project requires very specific clouds and you can use tool assistance to generate the maps.

For the **Cloud Map**, the color channels represent:

* **Red**: Coverage. Specifies the density of the clouds across the Texture.
    * Values closer to **0** represent an area of the clouds less affected by noise.
    * values closer to **1** represent an area of the clouds more affected by noise.

* **Green**: Rain. Specifies the areas of the clouds that are lighter/darker.
    * Values closer to **0** represent an area of the clouds with less rain that are lighter in color.
    * Values closer to **1** represent an area of the clouds with more rain that are darker in color.
* **Blue**: Type. Maps along the cloud lookup table's horizontal axis to specify cloud properties at the world position the texel Texture represents.

For the **Cloud LUT**, the color channels represent:

* **Red**: Profile Coverage. Determines the density of the cloud based on its height within the cloud volume.
* **Green**: Erosion and shaping. Determines which areas of the cloud volume are more susceptible to erosion and shaping. Values closer to 1 mean the cloud is more susceptible to erosion and shaping.
* **Blue**: Ambient Occlusion. A multiplier that HDRP applies to the ambient probe when it calculates lighting for the volumetric clouds.

When importing these two map Textures, disable **sRGB**. For best results, do not use any compression.

**Note**: This cloud map is formatted differently to the cloud map that the [Cloud Layer](create-simple-clouds-cloud-layer.md) feature uses.

![](Images/volumetric-clouds-3.png)