Skylights and environment lighting

- [Voiceover] In the early days of 3D video games,…unlit lighting mode was all you had,…and in a way this equates to a single ambient light.…In the context of lighting you can think of it…as everything being uniformly lit.…In other words, as a uniform ambient light.…The real world, however,…is not uniformly lit.…We need to vary the intensity in color…as a result of both direct and indirect lighting.…An environment map is the easiest way to do this,…and as I'll demonstrate,…it can simulate both direct and indirect lighting.…An environment map is a term that covers both…cube maps and lat-long maps,…and Unreal supports both of them,…although you're encouraged to use lat-long maps.…

Lat-long maps are also called HTIR maps.…HTIR maps, HTIR light maps,…and there are probably other names…out there as well.…Whatever the name, lat-long maps…are authored to map a 2D image to a 3D sphere,…much the same way that a regular old map…that you'd use to find your location maps…to a 3D sphere that is our planet.…The environment map I'm using for this scene…