For sunset, moonlight and mist, the sun/moon is generally more effective if it is visible in the picture. Refer to page 4 for instructions on bringing the sun into a scene.
The effects of the settings for a sunset are most easily seen if there is only sky and water, so before applying a sunset to the scene I am making, I have closed down and relaunched Terragen to return all settings to their defaults, and, without generating a terrain, have added a cloud layer and set the water settings at maximum for the four sliders on the right of the water panel, and set the water level to 0. I strongly recommend doing your own experiments with the settings to get the feel of making a sunset, in which case set the water level to whatever figure gives you water. Usually the figure falls somewhere between -3 and 1.
For this first sunset I brought the sun into the centre of the picture, and lowered it till it is just above the horizon, with sun altitude on the light control at 5.38. The sun's corona is reduced to 0. Decay/red is unlocked from atmospheric blue, in case I need to make colour changes, and set at 40%. All the other settings are at their defaults for this first picture.
Simply moving the sun up and down the sky can make a difference to the colour of both the sun's disc and the sky and clouds. As it is lowered towards the horizon, everything takes on a reddish tinge, which is then increased by adjusting the decay/red setting. You should experiment with moving the sun and adjusting decay to familiarize yourself with the effects. You can also change the colour of the atmospheres, and of the sunlight itself, but I have not done this in these sunset pictures.
For the picture on the right, I used the following settings:
On the light control panel, sun's corona at 0. Sun altitude still at 5.38. On the lighting of atmosphere tab, glow amount reduced to 80%.
On the atmosphere control, panel, simple haze set to 40%, decay unlocked from atmospheric blue (though I have not, in fact, changed the colours) and set at 55%.
You can see that this has darkened the red in the sunset, and the reduction of the glow combined with the increase in simple haze has made the sun itself appear more like a disc.
I cannot in this tutorial show you every possible combination of setting. The atmosphere settings, the sun's height and direction, glow amount and power, and the colour of the atmospheres and of the sunlight can all be adjusted, but the starting point is always to have the sun low in the sky and the decay setting higher than its 20% default. It is worth spending time experimenting with adjusting the settings because there is a huge range of effects available from changing and balancing them. If you want to adjust either the atmospheric blue or light decay/red colours, first unlock the light decay colours from atmospheric blue.
Finally, I am going to apply a sunset to the picture I am building up throughout this tutorial. My starting point was the settings for the last render, in the centre of page 5.
It is not possible to place the sun in the centre of the picture and low on the horizon, because it would be hidden behind the mountains. The sky would have a reddish glow, but the rest of the scene, including the water, would be in deep shadow. So I have placed it in the corner of the picture at the left, above a dip in the mountains. Although it would have been possible to bring the sun a little lower in the sky and still have it visible, to do so would have made the shadow of the mountains cover the water, and there would have been no reflection of the sunset sky in the lake. The sun's altitude is 9.84. I have used multi-directional shadow lighting, with a shadow lightness setting of 34.81. I have reduced the glow amount to 80%, and the sun corona is at 0.
Light decay/red is set at 50%. It would have been possible to have taken this higher, giving a more dramatic red sky, but the foreground snow and the tops of the nearer mountains are already tinged with pink and the shadows are tinged with blue. As they stand, the eye accepts that as the effect of sunset. Even though, in nature, they might very well be much deeper colours, when we looked at the picture we should probably reject darker shades as being unnatural and over dramatic.
This is the next stage of my picture, and although I am going to digress and alter the settings to demonstrate night and mist settings, this will be the basis for the next development of the scene. This being so, I have saved the world file again (World File/Save World), because that will preserve not only the direction of view, but all the sun and lighting settings, and for the first time have saved the atmosphere settings, using the save button on the atmosphere control panel, and that will save all the settings from that panel.
To reload the complete picture I now have to load the terrain and the snow/grass surface, the world file and the atmosphere file. I also have to make the child settings for surface B, set the second colour for surface BA, set the distribution settings for surface and surface B, add a cloud layer and set the water settings.