Help me create fog for my movie. I suffer for three weeks, I can’t make a smooth transition so that the fog is only in the distance of the landscape. I cannot use planes with fog because the camera is moving. I also can not use the scatter for the world because I need a clear sky. I came up with only such an option - snap a large cube to the camera (Copy Location), which only moving along the X and Y axis. Next, I mix two gradients in the material, a Linear gradient for a smooth transition into the sky and a Spherical gradient in the center of the cube because there should be no fog near the camera. It seems simple, but in the end I get a dark scene or a sharp circle without fog in the center. Help adjust the transducers so that the fog matches the gradient and looks natural. How to make the most distant objects of the landscape completely in the fog, which gradually passes into the sky? Blender 2.82 file in Dropbox (IronDump_fog.zip 56.5MB)- https://www.dropbox.com/s/abw6hz2q409bwxo/IronDump_fog.zip?dl=0
Best solution that doesn't take incredibly long to render is to use the Mist pass and composite in the fog. On the View Layers tab turn on Mist.
Then, in the compositor, turn on Use Nodes and add a Mix node between the Render Layers node and the Composite Node. Plug the Mist output into the Fac input on the mix node. The bottom slot controls your mist color, but you can also plug any other texture into this. You could for instance in another scene create a flat plane with an emission shader and a noise texture added to it and animate the texture node z position. This would look like clouds moving towards you. Then plug this animated texture into the bottom image slot the Mix shader in your main scene.
The falloff of the Mist is controlled in the Mist Pass panel in the World tab. Depth controls how far into the mist you can see. I would animate this to simulate the effect of changing fog density as you move across the landscape. Basically the thicker the cloud, the lower the depth.