You used VRscans for the car materials - what do you like about them?
Whatever lighting situation you use them in, they always look real and very detailed. In this case, instead of just using a simple black car paint, I used a blue one and adjusted the gamma so it became a lot darker, but it still featured some nice blue flakes. That's what I also like about VRscans: they are realistic but still pragmatic when you need to change things around.
I also used VRscans for some parts of the pipes on the rooftop, other metal parts and the mirror glass on the buildings.
Could you tell us about how you created the ground?
Rooftops are usually pretty simple and clean, but I did some research and found some crazy dirty ones, and loved them because they are visually more interesting. Besides various high-quality textures I used from Friendly Shade, the displacement and stone scattering are probably the most important aspects.
I used a 30,000-pixel texture for the displacement by mixing various depth maps. For the puddles, I displaced the ground by around four centimeters, then created a plane with a water material applied with a Phoenix FD Ocean Texture as a bump. This is visible at certain displaced spots.
Using Forest Pack by iToo Software, I scattered stones around and applied randomized stone materials and Stochastic Flakes via a VrayBlendMtl, so you see randomly colored highlights depending on the lighting conditions and angle. This creates some interesting bokeh!