Occlusion and directionality in image based lighting: implementation details

I got a few follow-up questions on the blog post I published a few days ago on occlusion and directionality in image based lighting, so I put together a quick follow-up to elaborate on a few points and add some more resources.

To implement the main technique the exploration was based on, Ground Truth ambient occlusion, it is worth starting with the original paper by Jimenez et al. This is best read in conjunction with the Siggraph 2016 presentation, it will help to understand the paper better. The paper also includes fairly detailed pseudo-code for the GTAO and bent normals implementation, it will help to also use Intel’s implementation of the technique as a reference, it clarifies some parts of it as well. At the moment the sample does not seem to implement directional GTAO, in which the visibility cone is combined with the cosine and projected to SH.

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Notes on occlusion and directionality in image based lighting.

Update: I wrote a follow-up post with some implementation details and some more resources here.

Image based lighting (IBL), in which we use a cubemap to represent indirect radiance from an environment, is an important component of scene lighting. Environment lighting is not always uniform and has often a strong directional component (think sunset or sunrise or a room lit by a window) and that indirect light should interact with the scene correctly, with directional occlusion. I spent some time exploring the directionality and occlusion aspects of IBL for diffuse lighting, with a sprinkle of raytracing, and made some notes (and pretty pictures).