Based on the research and paper by Aldo Borgonovo & Goffredo Haus (Computer Music Journal, 1986), this implementation demonstrates 3 of the terrain functions described within the paper.

A rich and dynamic variation in spectra can be generated with just a few controls, particularly when combined with time-varying control over the X & Y amplitude.

This lab version uses LFO modulation to see the effects of amplitude and phase modulation on the terrain.  Additionally, a simple example of using amplitude envelope to move through the terrain is included.