VAO works by approximating amount of light that can reach given pixel taking volume of surrounding geometry into account. We have developed fast approximation algorithm and use fine-tuned random samples sets to calculate it in real time. Ambient occlusion will add depth and realism to your scenes.
Our algorithm works in screen space (using only normals and depth values readily available in G-Buffer). Therefore, there is no performance hit when using more complicated meshes (more polygons) and it makes use of bump textures automatically. It is also fully dynamic - there is no need for pre-calculating specific scenes and it works with both static and moving objects.