The Screen Space Ambient Occlusion Volume Override contains the settings that control how ambient occlusion appears in your scene. To add it, select a Volume, then select Add Override > Lighting > Screen Space Ambient Occlusion.
The Volume Override configures ambient occlusion but doesn’t enable it. The Screen Space Ambient Occlusion Renderer Feature must also be present and enabled on the Universal Renderer that your camera uses.
Which properties appear depends on the Mode you select and on whether you enable Use Compute Shader. The properties in Quality Settings are read-only unless you set Quality to Custom. For an explanation of the two modes, refer to Ambient occlusion modes in URP.
The Screen Space Ambient Occlusion Volume Override contains the following properties.
| Property | Description |
|---|---|
| Mode | Sets the ambient occlusion algorithm that URP uses:
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| Sampling Method | Sets the noise pattern that URP uses when it samples occlusion:
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| Intensity | Controls the strength of the ambient occlusion. Higher values produce darker occlusion in creases, holes, and surface intersections. The default is 0.4 and the minimum is 0. A value of 0 disables ambient occlusion. |
| Radius | Sets the radius in world units around each point where URP calculates occlusion. Larger values produce broader, softer occlusion but sample more of the texture, which reduces performance. Lower values sample pixels closer to the source pixel, which makes caching more efficient. The same value covers much more of a small object than of a large one, so set it to suit the size of the objects in your scene. The default is 0.3 and the range is 0.01 to 5. |
| Falloff Distance | Sets the distance from the camera up to which occlusion is visible. Beyond this distance the effect fades out. Lower values improve performance in scenes that contain distant geometry. The default is 100 and the minimum is 0. A value of 0 disables ambient occlusion. |
| After Opaque | Applies the occlusion after the opaque pass instead of during lighting. This is faster, particularly on mobile platforms that use tile-based rendering, but less accurate, because URP applies the occlusion after it evaluates the shading model. Surfaces that receive baked occlusion can over-darken, and already lit or emissive surfaces can darken. Disabled by default. |
| Direct Lighting Strength | Controls how visible the occlusion is on surfaces that direct light sources illuminate. At 0, occlusion affects only indirect lighting. Higher values apply it more uniformly across all lighting. The default is 0.25 and the range is 0 to 1. This property has no effect when you enable After Opaque. |
| Minimum Radius (Pixels) | Sets the smallest area, in pixels, that GTAO samples around each point. Distant objects cover fewer pixels on screen, so the area that Radius covers can become very small and occlusion fades away. This property keeps occlusion visible on distant geometry within the Falloff Distance. Larger values keep occlusion visible further away but sample a wider region of the screen. The default is 40 and the range is 1 to 256. This property is available only when Mode is GTAO. |
| Use Compute Shader | Calculates GTAO with a compute shader instead of the fragment path. The compute path provides the Spatial Filter, Direction Count and Step Count properties, and the Temporal Accumulation settings. On platforms without compute shader support, URP falls back to the fragment path and these settings have no effect. The Editor displays a warning when compute shaders are unavailable. Disabled by default. This property is available only when Mode is GTAO. |
| Spatial Filter | Sets the filter that URP uses to reduce noise in the GTAO result:
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The Quality Settings group contains the following properties.
| Property | Description |
|---|---|
| Quality | Sets the preset that URP uses for the other properties in this group:
URP applies a preset only when you enable this property’s override, and a preset configures only the properties that apply to the current mode and path. When a preset is active, the following properties report the preset’s values rather than the values stored on the override. |
| Depth Source | Sets where URP reads depth and normal data from:
This property is available only when Mode is SSAO. It has no effect in the Deferred and Deferred+ rendering paths, which use the normals that the G-buffer already contains. |
| Normal Quality | Sets how many depth texture samples URP takes when it reconstructs normals from depth. Higher values produce more accurate normals but reduce performance:
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| Downsample | Calculates the occlusion texture at half resolution to improve performance. This reduces the number of pixels that URP processes by a factor of four, which lowers the load on the GPU significantly, but produces a softer, less detailed result. This property is disabled by default. |
| Blur Quality | Sets the blur that URP applies to the occlusion texture to reduce noise:
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| Sample Count | Sets how many occlusion samples URP takes per pixel. Higher values reduce noise and produce a smoother, more detailed effect, but reduce performance. In SSAO mode, the options are the following:
This property is available only when Mode is SSAO, or when Mode is GTAO and you disable Use Compute Shader. |
| Direction Count | Sets how many directions GTAO searches around each pixel. More directions improve quality but reduce performance. The default is 2 and the range is 1 to 8. This property is available only when Mode is GTAO and you enable Use Compute Shader. |
| Step Count | Sets how many steps GTAO takes along each direction. More steps improve quality but reduce performance. The default is 4 and the range is 1 to 16. This property is available only when Mode is GTAO and you enable Use Compute Shader. |
The Low, Medium and High presets configure the following values.
| Property | Low | Medium | High |
|---|---|---|---|
| Downsample | Enabled | Enabled | Disabled |
| Sample Count | Low | Medium | High |
| Depth Source | Depth | Depth Normals | Depth Normals |
| Normal Quality | Low | Medium | High |
| Blur Quality | Low (Kawase) | Medium (Gaussian) | High (Bilateral) |
| Direction Count | 1 | 2 | 4 |
| Step Count | 2 | 4 | 6 |
Temporal accumulation uses data from previous frames to reduce noise and stabilize the effect over time. It’s useful when you use low Direction Count and Step Count values, or when you enable Downsample.
The Temporal Accumulation group is available only when Mode is GTAO and you enable Use Compute Shader. It contains the following properties.
| Property | Description |
|---|---|
| Enable | Combines the occlusion results from previous frames with the current frame. URP rotates and offsets the sampling pattern each frame and combines the results. This requires motion vectors, which URP adds to the frame automatically when you enable this property. Disabled by default. |
| Ghosting Mitigation | Controls how much data URP discards from previous frames. Higher values reduce ghosting and trailing behind moving objects, but reintroduce noise. The default is 0.5 and the range is 0 to 1. This property is available only when you enable Enable. |
| History Length | Controls how many frames URP accumulates. Higher values produce smoother, more stable results but increase ghosting. The default is 0.9 and the range is 0 to 1. This property is available only when you enable Enable. |