title: Procedural Terrain with ridged fractal noise
body: <p>I implemented bilinear interpolated white noise in order to procedurally generate terrain.</p>
  
  <p>I can obtain this kind of result:</p>
  
  <p><a href="https://i.stack.imgur.com/jDdOM.png" rel="noreferrer"><img src="https://i.stack.imgur.com/jDdOM.png" alt="enter image description here"></a></p>
  
  <p>I would like to implement ridged fractal noise to get a more realistic terrain like:</p>
  
  <p><a href="https://i.stack.imgur.com/Jk6PZ.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/Jk6PZ.jpg" alt="enter image description here"></a></p>
  
  <p>However I can't find a good tutorial for ridged fractal noise. Can you explain to me how to do this?</p>