GTAO Quality

This page describes parameters under the "Quality" foldout that are specific to GTAO mode.

Resolution

Determines the resolution at which the effect is rendered. This parameter has the greatest impact on performance and visual output.

• Full: 100% of pixels are rendered. Achieves maximum quality.

• Half: 50% of pixels are rendered in a checkerboarded (non-temporal) pattern. A good balance between performance and quality.

• Quarter: 25% of pixels are rendered. The most performant of the three modes.

Performance impact: most severe, consider carefully

Full

Half

Quarter

Tracing Mode

Defines the algorithm used for occlusion calculation.

• Horizon Search: the default GTAO algorithm, introduced in the original paper and refined over many iterations. Works fast, but struggles with object thickness at large radii. Strongly relies on falloff to avoid haloes.

• Visibility Bitmasks: a more novel approach that simulates rays passing behind objects, similar to traditional ray marchers, producing results closer to ray tracing — but at a performance cost.

Performance impact: moderate

Horizon Search, WS Radius 3

Visibility Bitmasks, WS Radius 3

Slice Count

Specifies the number of directions (slices) used to evaluate occlusion. The final sample count is calculated as "Slice Count × Step Count × 2". Each increment in the Slice Count significantly increases the number of samples. This parameter has the greatest impact on noise reduction (aside from the denoiser itself) but comes with a substantial performance cost.

Performance impact: severe, keep as low as possible

Slice Count 1

Slice Count 2

Slice Count 3

Step Count

Specifies the number of steps taken along each direction (slice). This parameter determines the accuracy of occlusion and affects noise levels, although to a lesser extent than the Slice Count.

Performance impact: severe, keep as low as possible

Step Count 8

Step Count 32

Thickness Mode

This option appears when Tracing Mode is set to Visibility Bitmasks. Defines the method used for thickness calculation.

• Uniform: keeps thickness constant, producing more precise and stable intersections at the cost of reduced occlusion in the distance.

• Linear: increases thickness linearly with distance, keeping occlusion more visible on distant objects, but may over-occlude thin geometry.

Performance impact: none

Uniform Thickness 0.2

Linear Thickness 0.2

Thickness Value

This option appears when Tracing Mode is set to Visibility Bitmasks. Controls the virtual thickness of objects. Since a screen-space algorithm uses the depth buffer to find intersections, it has no way of knowing the true thickness of objects. Instead, an arbitrary parameter is used — the higher this value, the stronger the occlusion cast by all objects.

Performance impact: none

Thickness Value 0.1

Thickness Value 0.5

Use Attenuation

Specifies whether falloff should be applied during the occlusion evaluation. Bitmasks are originally designed to work without falloff. However, this can cause the occlusion appearance to deviate significantly from the non-bitmask variant, which has more contrast in crevices and quickly fades to pure white.

Enabling this option allows the bitmasked GTAO to more closely match the non-bitmask variant in terms of contrast distribution. Disabling it makes the bitmasked GTAO resemble RTAO more closely.

Performance impact: negligible

Use Attenuation OFF

Use Attenuation ON