I love using Fresnel effects to achieve the "Super Mario Galaxy" look - rim lighting, and glossy reflections on rough, solid surfaces. But here, it's used to give a softer look to the lighting and break away from the Lambert diffuse we're so used to. Rough surfaces are brighter on grazing angles, and this is what I try to mimic. Smooth, reflective surfaces aren't. You can see the green glass does get more green at grazing angles, though.
Roughness on clean surfaces should be uniform, otherwise it will look like the painter made a mistake, and patches will look shinier than others. Not much interesting going on here, except I did make sure the grout is not as reflective as the tile, otherwise the whole thing would look slick and weird.
Speaking of glass at grazing angles, I am getting that thick green glow by using a custom depth fade. It's very easy to see here. Combined with the Fresnel effect and the full metallic surface gives the glass its heavy "glass" look. Otherwise, it would just look like cheap acrylic.
The water also uses depth fade to drive a color ramp.
The tiles, bubbles, and even the stucco texture on the walls have parallax (bump offset) to get better depth. The sand even has parallax occlusion for very dramatic lumps. In VR, I imagine this would look amazing. The tiles even have a bit of random tilt in the normals to scatter the reflections.
The curved reflections in the glass on the right gives a neat space age look, and UE4's SSR does a pretty good job. But RTX would still resolve better around the bend. The water has an inclusive planar reflection: it's quite expensive (3ms at 1440p on an RTX 2060 Super, about 20% of the frame total), but it adds depth and drama to the environment in every shot. Using 3 sphere reflection captures to cover gaps, everything in this building has a reflection.
Of course, the many layers of translucency are quite expensive. Using simpler hard-coded reflections would be much cheaper (the columns could be better optimized), but for PC this is quite tame. In this game, users can adjust graphics settings and scale resolution to their needs. The floor is the most expensive portion of this whole game. I think it's worth it.
The lighting, unfortunately, was a huge tradeoff. Baking is impractical for an open world, so I opted for all dynamic with SSGI. Without SSGI you can see the light is rather harsh, especially when it fails to brighten the ceiling. It's hard to tell, but the sun is warmer and the skylight is cooler, providing some nice color contrast.
Here is the final image without any post process at all: no bloom, no lens flares, no color grading, etc. It looks rather hard and sharp, and quite even. This is good: it will give you more room to play with in post.
And finally, when it all comes together. SSGI lights up the ceiling a bit, but better GI would handle that much better. The bloom gives the light a strong presence and really brings the image to life, while hiding imperfections. I color grade with more reds in neutrals to make the cyan and blue really pop. There is so much interaction with the light and reflections in this image the colors just mix beautifully.
Nighttime shots hide the imperfections even more, and look quite stunning ;)