In the early pages of the tutorial I covered only enough of the options on the terrain generator to allow you to get started on generating a picture. Now I want to deal with the various options available in more detail.

When you click the generate terrain button on the main terrain generator interface, this is the dialogue box presented. There are two choices of method. At the time of writing the Subdivision method gives a more realistic landscape than the Perlin method which is not yet fully developed. However, the Perlin method can give an excellent landscape if you glaciate and canynonize after generating.

In the comparison pictures below, it is not always possible to show the effects of the various settings on an identical landscape, so I show typical scenes generated by the settings. Glaciation and canyonism will be fully covered in this section, but at this stage I have simply generated scenes which use them, without explaining them, to show the difference between Subdivision and Perlin.

SUBDIVISION METHOD Default settings - no modification	PERLIN METHOD No modification	SUBDIVISION METHOD Modify/glaciate and canyonize	PERLIN METHOD Modify/glaciate and canyonize

It is clear from these examples that the most realistic landscapes are generated by the Subdvision method, unmodified, and the Perlin method modified by canyonize and glaciate. The other two settings are more suited to fantasy landscapes.

The Action settings are self-explanatory. You can choose between destroying the existing terrain and generating a completely new one, or generating some new features on the terrain you already have.

The size of features settings can have a dramatic effect on the look of a landscape. In these next four examples all the settings are at their default positions, except the size of features slider.

SLIDER AT minimum	SLIDER MOVED 3 positions to right (central)	SLIDER AT default position	SLIDER AT maximum

Although the default and maximum size of feature settings seem to give the most natural scenery, it is not usual to make very extreme alterations, or to adjust just one setting alone. Usually the various settings are balanced against one another, and quite small movements of one or more sliders can change to look of a landscape. But in order to show you how each of the other four settings affect the landscape, I am going to take all the settings to zero except the one I am demonstrating. This will not give a balanced looking landscape most of the time, and some of the results will be highly unnatural, but you need to know how each one works in order to be able to combine them effectively. I shall leave the terrain method at Subdivision and the size of features slider in the default position.

First, Realism. Realism at 0 generates a tangled mass of hills, all very rugged and angular. As the value is raised, the angularity is smoothed out. The default setting is a fairly natural compromise between the two extremes. At the maximum setting the landscape is quite smooth and undulating. Realism has its greatest effect on flat areas in the landscape, smoothing out valley floors.

Since the first of these settings has all the sliders at 0, this image will be the control for all of the comparisons.

REALISM 0	REALISM 35	REALISM 70 (default)	REALISM 100

Smoothing has a similar action to realism, but it is not exactly the same. Up to the default settings of both, (70 realism, 50 smoothing) the two seem to be very similar, but at 100, realism continues to smooth out the angularity of the landscape, whereas smoothing gives a terraced effect to the slopes.

SMOOTHING 0	SMOOTHING 25	SMOOTHING 50 (default)	SMOOTHING 100

Since realism and smoothing are usually used in combination, to balance each other's effects, the pictures below show some of the combinations of settings. The default settings give a natural look, not too rugged and not too smooth. When one setting is high and one low, the scenery is more rugged, but with a slightly different character to the ruggedness. With both at maximum, the flat foreground is very smooth, but the medium distance slopes show the terracing characteristic of high smoothing.

DEFAULT SETTINGS realism 70 smoothing 50	HIGH REALISM LOW SMOOTHING Realism 80 Smoothing 25	LOW REALISM HIGH SMOOTHING Realism 30 Smoothing 85	MAXIMUM REALISM AND SMOOTHING Both settings 100

The best way to become familiar with these settings is to play with them. Generate a lot of scenes, varying the settings, until you begin to be able to predict the sort of look you will get with a particular combination.

On the next page we shall continue to look at the terrain settings.