Dynamic Ambient Occlusion vs Static Baked Maps

Ambient occlusion (AO) is a rendering technique used in game development to simulate soft, contact shadows where surfaces intersect or block ambient light. While static baked AO maps pre-calculate these soft shadows into textures during development, dynamic ambient occlusion calculates them in real time on the GPU. The choice between these two approaches fundamentally impacts a game’s visual realism, memory footprint, and runtime performance.

Visual Differences

Dynamic ambient occlusion adapts in real time to shifting geometry, moving characters, and changing light environments. Techniques such as Screen-Space Ambient Occlusion (SSAO), Ground-Truth Ambient Occlusion (GTAO), and Ray-Traced Ambient Occlusion (RTAO) dynamically generate contact shadows under a player’s feet, beneath vehicles, or around dynamic objects. However, screen-space methods can exhibit visual artifacts, such as occlusion disappearing when an occluding object moves off-screen, haloing around silhouettes, or temporal noise. Ray-traced alternatives solve these screen-space limitations but may introduce subtle noise patterns if denoisers are improperly tuned.

In contrast, static baked AO provides pristine, artifact-free visual fidelity. Because offline renderers calculate baked maps without real-time constraints, they deliver smooth, noise-free gradients and physically accurate light attenuation, even deep within complex geometry. The visual limitation of static maps is rigidity: they cannot react to moving entities, destructible environments, or dynamic time-of-day cycles. If an object with a baked AO map moves, its static shadow moves with it, breaking visual immersion.

Computational Differences

The computational divide between dynamic and static AO centers on runtime GPU workload versus memory consumption.

• Dynamic AO (High Runtime Cost, Low Storage Overhead): Dynamic techniques require active GPU processing power every frame. Screen-space techniques sample depth and normal buffers to estimate occlusion, while ray-traced methods trace actual light rays through a dynamic bounding volume hierarchy (BVH). While dynamic AO requires little to no dedicated texture storage, it demands substantial GPU compute time and memory bandwidth, which can reduce frame rates on lower-end hardware.
• Static Baked AO (Zero Runtime Cost, High Storage Overhead): Static maps require virtually no GPU runtime compute because the shadow values are read directly from standard texture samplers. The trade-off is dedicated texture memory (VRAM) and storage disk space. Unique lightmap UV channels and high-resolution texture maps must be loaded into memory, which increases game install sizes and overall texture streaming pressure.

Hybrid Workflows

Modern game engines, such as Unreal Engine and Unity, often combine both methods. Developers frequently bake static AO into background environments, terrain, and immobile architecture to preserve runtime performance and visual quality, while simultaneously applying dynamic screen-space or ray-traced AO to characters, foliage, and interactive props. This hybrid pipeline maintains high frame rates while ensuring that dynamic game elements remain visually grounded within the world.