Abs Scalar produces an absolute value from its input. In effect it turns all negative values positive.
Here is a cosine wave passing through a zero ground plane.
Abs_Scalar_01.jpg
When we pass the signal through an Abs Scalar, all values below the zero plane become positive.
Abs_Scalar_02.jpg
This method can be used to turn Perlin Noise...
Abs_Scalar_03.jpg
...into Perlin Billows.
Abs_Scalar_04.jpg
If there's any errors, omissions or questions about the above, please leave a comment and we will add further details in this post when relevant.
https://planetside.co.uk/wiki/index.php?title=Abs_Scalar