So create simple terrain, and some object on it. I created high tech tower, but you can make whatever you want, just add some small details, because I’m going to show you how to make them more obvious.

So for start you’ll need to load Mental Ray. To do that go to window/settings preferences/plug in manager. Enable Mayatomr.mll

In render globals choose Mental Ray. In Mental Ray globals, you can see environment tab. Hit Create Physical Sun and Sky.

In attribute editor, mia_physicalsky1 will appear. There are menu options, I’m going to show you only few most important.

Also there’s directional light in the scene. This light controls the direction of the sun and also the time.

If you render, you’ll get something like this.

In quality presets choose previewFinalGather. This will set sampling little higher than draft.

On sunDirectionShape, in custom shaders tab, you’ll se that light has light shader, and photon emitter connected.

Mia_physicalsun defines the sun itself. Samples define the number of rays used for shadows. Increase this number if there’s noise in shadows.

In hypershade, you can see all shaders used in Sun and Sky system. There’s mia_exposure_simple1 applied as lens shader on camera. This node remaps colors to the way human eye sees. In Mental Ray all intensities are in linear space. Human brain sees color in different way. Basically it’s logarithmic function. That’s why gamma is 2.2. That’s the way we see, same thing for all photographs. So if you apply texture to objects you will get something like this: