Like sunset and night scenes, mist and fog effects are achieved by changing the colour and intensity of the atmospheres and light settings. They are at their most effective if there are hills at different distances from the camera, so that the distant ones are hazier than those nearer. The presence of the sun in a mist covered sky can also give atmosphere to the scene.
The picture on the left is the one we are going to turn into a misty scene. In the picture on the right, the simple haze density has been raised to 50%. This gives the sort of haze you might find on a hot afternoon - heat haze. Distant mountains are still clearly visible, though there is enough haze to emphasize their distance. The sky too is less vivid. The foreground is a little less bright, as you would expect if the sun becomes hazier.
Raising simple haze to 80% gives a realistic mist (left). The distance between the various ranges of hills is emphasized, and it is clear now that there are two foreground hills on the left, one much closer to the camera than the other. However, the mist has a bluish tinge which is not natural.
On the right, the colours of all three atmospheres have been changed. Light decay/red is unlocked from atmospheric blue.
These are the settings used:
Simple haze. R 128 G 128 B 112 Density 80% Half height 64
Atmospheric blue. R 123 G123 B 70 Density 20% Half height 128
Light decay/red. R 138 G 138 B 80 Density 20% Half height 128
A final improvement would be the sun's disc just showing in the mist. I am going to put the sun in the top right corner of the picture, so that any residual effect from its light will lighten the foreground hill which has become rather dark and silhouetted.
I have made a larger render of this finished scene so that you can see that the progression from distance to foreground is very realistic, with detail becoming more discernible in the mist in a very natural way. Before making this final render, I made two changes to the settings I had used throughout these examples. I changed the shadow lighting from single colour to multi directional on the lighting control background light tab. This removed the last hint of blue from the mist, but it also emphasized the clouds in the sky, which would not be there on a foggy day. So I also removed all clouds from the sky by going to the cloud generator and setting density shift to -92. (We shall be studying clouds and cloud generation later in the tutorial.) The sun's light has improved the appearance of the foreground hill and it is no longer such a dark area with few details visible. These are the light settings I used for the sun:
Sun altitude. 24.2059
Direct sunlight tab. Sunlight strength 175% Effect of atmosphere 130% Realistic sunlight penetration system with sunlight base colour and cloud cover at default settings.
Background light tab. Multi directional shadow lighting. Shadow lightness 64%.
Sun's appearance tab. Disc diameter 1. Corona size 0
Lighting of atmosphere tab. Glow amount 36%. Glow power 80%
Finally, I want to apply these settings to the tutorial picture, starting with the settings for the rendering of the picture on page 5.
I was able to use the settings exactly as for the previous picture. Although the snow means that the distant mountains are showing some detail, the progression from mist to clear is still realistic. Even the water on the far side of the lake shows no waves or detail, whereas there are waves in the water nearest to us.
We turn now to a sophisticated use of atmospheres and lighting that was introduced in Terragen v. 0.8, the sun casting sunbeams across the sky.