Time for another round.

I was reading about clamped perlin noise in another thread and gave it a try.

Starting with the default scene I always unhook the "Terrain" nodes from the "Compute Terrain" node first. In goes the "Displacement shader" node.

Here I can connect to all the blue node functions I come up with.

In this example I take a "Perlin 3D scalar" node, feed a "Get position in geometry" into the input and try to find a interesting or useful pattern.

Constant scalars going into the "Scale" and "Seed" input of the "Perlin 3D scalar" node. The "CS Perlin Scale" node carries my initial scalar value

(which looked good to me together with the "Seed" node number).

Using the "Multiply Scalar" node with a "Constant Scalar" node as multiplier is like using a slider. This way I keep the initial value I liked so far and

only change the multiplier to change the scale of the pattern. Setting it to 1 resets to the initial value.

I tend to forget the values I change after a few minutes testing and trying... Now I have the pattern I want to go on with.

Then I use the "Length to scalar" node. The node calculates the length, or magnitude of the input vector and then outputs the length as a scalar (Wiki-text).

So, it takes the set of three scalars the vector consists of, and then uses a formula (explained in the Wiki Node Reference) to calculate a single scalar value.

The node views illustrate the steps from Perlin 3D Pattern over Length to scalar to the then clamped output. As you can see disabling the conversion node

(Length to scalar) and connecting the "Perlin 3D scalar" directly to the "Clamp scalar" Input yields a very different result.

Which lets me choose how I want to go on.

The "Divide scalar" and its "Input 2" could be replaced with a "Colour Adjust shader".

They work essentially the same. With the "Divide scalar" node you only need to control one value (CS Divide Input 2).

Faster and easier for the time being.

Feed this into the "Displacement shader"s "Function" input and adjust the value in the "Displacement multiplier" field.

Putting in a positive value will give you something like trenches, carvings, engravings or whatever these things are called;

using a negative value lets rise the ridges (or lowers the rest).

The brownish areas are the result of the "Fractal terrain" attached to the "Input node" of the "Displacement shader".

That`s it. Hope these easy setups are useful to someone (and hopefully I did not mess up the description

).

Cheers, Klaus