The appearance of water in Terragen pictures is controlled from this panel, which you access by pressing this button.
The first control, at the top, is the water level which has a default setting of -10. If you do not want sea, lake or river in your image, set this at some ridiculously low level such as -1000. When you have set this, click Update Maps. All the blue areas will disappear from your terrain map, and if you render the image, what was formerly water is now low lying land - grassland if you are still using the grass and rock surface map.
Raising the water level has exactly the same effect as raising it in real life. The water area expands, and more of the landscape is 'drowned'. These examples show the result of raising the water level from -10 to 10 with the terrain I was using in Page 1.
Fortunately the camera height, which is given on the Render Control panel as the z(alt) parameter for the camera position, is 11, one above the water height, so the water is visible. Although in the terrain it appears to be on the water, it is actually hovering above it. If we were to change the height to 10 and render again, there would be a large black area in the foreground of the picture, like the one in the second example on page 1.
For the rest of this page I have set the water level at -3, and the camera altitude position at z(alt)=1. This gives us a good balance between water and hills, with strong reflections, and water in the foreground, so that we can see the effects of all the changes.
There are four diffuse colours of water set as presets in the program. So far, I have used the default colour set for deep, which gives strong reflections as in deep clear water. The images below show the difference in the appearance of the water using the other three preset colours. For the frozen one, I have also changed to the snow heavy.srf surface map from the zip file downloadable from the link on page 1.
As you can see, these colours are very realistic. The muddy one is only visibly muddy close to the camera where there is a viewpoint down into the water to see its quality. Further away, where it is reflecting the sky and the camera cannot look down into it, it appears blue. The tropic one has the characteristic greenish tinge which is present in clear tropical waters, and which again becomes less marked with distance. In the frozen one the reflection of the mountain is much more diffuse, as though it is reflecting from the icy surface and not from deep water. This effect is greatly helped by the snow on the mountain, so that the mountain does not have the strong colours reflected in the other two pictures.
The diffuse colour can be changed to anything you like if you wish to have different or even surreal effects. Click on the colour panel to access the RGB controls for changing the colours. Clicking on any of the presets will restore that preset's default colours
The overall reflection properties govern the nature of the reflections, though other settings, such as water roughness or wave size will also have a bearing on them. The picture on the left has Maximum Reflectivity set at 200 and Reflectivity curve set at 100. If you compare it with the reflections in the examples above, you will see that reflection is much clearer, though still broken by the waves in the water. On the right, the same reflectivity settings operate but with Roughness and Wave Size both at 0. The reflection is now almost mirror like.
Reducing either of these parameters to 0, even if the other is at maximum, gives water which, at the Deep diffuse colour setting, looks like the Black Lagoon. (below left)
However, reducing them both, to Max Reflectivity 60 and Reflectivity Curve 30 gives a dark featureless reflection (below center) which can be very useful. Combined (below right) with the Muddy diffuse colour setting gives water which looks muddy and contaminated.
To show you the effect of wave properties, I have increased each to maximum in the images below, leaving the other at its default setting. With Roughness at maximum, (below left) there are no reflections in the water, and you can see, even in this small image, that waves close to the foreground have natural looking white caps.
Wave Size maximum, on the other hand, gives very undulating water. (below center) The reflections are still there, though very much broken up. Experiment with different combinations of these two settings to arrive at calm or disturbed water, and to make reflections look more or less clear. Below right shows both settings at 125. There is still a small but very broken up reflection, and the sea looks very choppy indeed.
The Visibility Effect dampens the effects of the other two sliders. Taking it to 0 will make reflections clearer, but it will also make roughness or wave size look more exaggerated, and often less natural. Below left shows Roughness at 200 and Visibility Effect at 0. The reflections have returned, but the rough sea is exaggerated to the point of being not nearly so convincing as in the one above left, where the Visibility Effect was at its default setting of 100. A similar effect is obtained with Visibility Effect at 0 and Wave Size at 200 (below second picture)>
But using Visibility Effect in moderation can enhance a picture. The third picture below shows the one above right, but with Visibility Effect reduced to 90. There is more reflection, and the sea is even choppier, but it all still looks natural.
The final settings on the water generator, Reflection of Lightsources, are most easily demonstrated with a sunset scene and sun shining across the water, so I have removed one of the mountains to give a clear sea horizon, and brought the sun into the picture. (See page 7 for making sunset scenes).
The first picture below left shows the default settings for Direct Sunlight and Reflection Spread. Other Lights is not implemented at the time of writing. Reducing Direct Sunlight to 30% gives you the second picture. In both pictures, the surrounding landscape is very dark, but in the second one the sunlight itself is less bright, and so we have scope for increasing the shadow lightness and the exposure, to give the picture on the right. The atmosphere settings could also be adjusted to darken the sky more if required.
I am staying with the last picture to show you the effects of Reflection Spread. In the pictures above it was at the default setting of 10. In the first picture below, setting 1, there is no stream of light across the water at all - just a simple reflection of the glow in the sky. In the second picture, setting 3, there is a short stream of light. At setting 20, twice the default - picture 3 - the stream of light reaches the foreground, and at the maximum 50, almost the whole sea glows, though it is not so bright.
The Reflection Spread setting can also be useful in daylight scenes. In the scene below left, the sun is out of the picture to the left, but is causing a reflection on the sea which looks odd, because the scene looks as though there is land there which would stop it from shining through. Taking Reflection Spread to 0 eliminates the unwanted reflection. (below right)
The water settings in Terragen v. 7.x produce beautiful and flexible water scenes, from the realistic to the surreal. There is no substitute for playing with them and experimenting to get effects that you like.