Great looking render
I love those hazy clouds, really nice!
Quote from: Hannes on November 07, 2011, 08:33:34 AM
Check: Atmosphere/Atmosphere/Quality/Receive shadows from surfaces. This makes the sun disappear behind the mountains. Rendertimes will be longer too. 
Do you have checked "Raytraced reflections" in the reflective shader? If you only need specular highlights, uncheck this. Rendertimes will be shorter.
Great image by the way! 
Another tip for the clouds: decrease the smallest scale of your cloud's density fractal (0.01 for example) and raise the roughness to 1.9 under "Density". This will produce more detail. You could play with the edge sharpness as well. It's all a matter of taste, but it's worth a try.
These are great tips. Please keep in mind that the "receive shadows from surfaces" will take roughly twice as long to render, if not more. An option could be to render a crop of the sun with that setting enabled and composite it in post.
On the other hand, calculated shadows casted from the terrain onto the clouds are more accurate and may add in realism.
So it's a trade off you'll need to choose from.
Always be careful when someone posts values to enter. 0.01 could make sense if your scales are already small, but if you have huge scale clouds you'll end up with details which will either never be notice-able/visible and it would also add unnecessary rendertime since you have a huge number of noise-octaves consequently (feature size / smallest scale = #noise octaves).
Adding roughness will create more detail in the fractal, but you'll need a minimum cloud density and edge sharpness to make it visible, but to some extend that's also possible by increasing fractal contrast.
These settings inter-relate heavily. It's difficult and you'll need to develop a bit of feeling for it.
A higher roughness value tends to create more "floating" small clouds around the main features which often looks less nice.
An approach could be to increase edge sharpness a bit first and see if that works.
If not, then revert to original edge sharpness and stepwise increase fractal roughness.
In your particular case I wouldn't increase density, because obviously you're going for some kind of transparency here which in my opinion you shouldn't touch!
