I finally have a PBR implementation in an engine that I'm writing for a game I'm developing but I'm stuck on how to use IBL in real situations. Most IBL tutorials use it just to show a single mesh or group of spheres but nothing that I can immediately translate to an in-game application.
So I was wondering, in an open world, how would someone go about implementing image based lighting? Different areas will require different environment maps to be generated and then there's the issue of time of day. I guess for that, you could just use values that you would use in your day and night shader to change the colours being sampled from the environment map but you still have the issue of having a large map.
Update: I've read about light probes and perhaps that's how this is achieved? Create probes around the whole map and then sample and interpolate between the probes that are near the camera. Is this how large open-world games achieve image-based lighting? This way you can have one light probe based on the skybox and multiple light probes spread across the scene and inside rooms.