Have a look at a six-hour workshop by Alessandro Cangelosi on how to create large-scale natural environments for visual effects and other projects. The artist discussed using Clarisse V4, Houdini, and Terragen to generate CG environments with the help of realistic skies, atmospheric effects, and procedural assets.
With this course, you will learn about using Terragen for the creation of realistic skies, clouds, and for generating backplates for image-based lighting techniques. Then, you will get tips on using Houdini for terrain modeling, mountains. You will learn how to add details of all sizes, how to use area masks, and more. There's more, of course.
You can learn more and get started here.
