HBAO (Horizon-Based Ambient Occlusion) is a technical term that is extremely important in the rendering and optimization of game graphics (technical art). An advanced version of SSAO, this high-quality ambient occlusion technology calculates the shadow occlusion rate by highly sampling the angle of the "horizon" around pixels, and expresses physically correct gap shadows that are much deeper, more precise, and free from distortion than SSAO.
An analogy in the real world: Rather than simply ``painting it black because it looks like it's depressed (SSAO)'', we precisely measure the angle of the slope of the depression (the slope of the horizon) in all directions, accurately identifying only the ``deep depths of the valley bottom'' where the beam of light really cannot reach, and adding shadows like a surveyor.
The GPU does not simply roughly scan the irregularities on the screen with a sphere, but instead calculates the ``physical occlusion angle (horizon angle) of mountains and valleys'' when looking around from a pixel to a poster It 100% prevents unnecessary shadows (stains) on flat surfaces such as the edges of the screen, and casts deep and beautiful jet-black shadows only in ``places where light physically cannot reach,'' such as the corners of a room or the neck of a character.
Illustration: HBAO (Horizon-Based Ambient Infographic that clearly illustrates the basic processing flow and mechanism of Occlusion) in Japanese.
Detailed mechanism and operating principle
Ambient occlusion Change the algorithm to "HBAO (horizon-based AO)", vector sample the surrounding 3D "horizon angle (slope)", and precisely sink shadows only in the true concave areas.