Besides Gaea and World Creator, World Machine is the go to terrain asset generator for VFX and game design. Adaptable to any material and map model it can render finalized assets as well as layered intermediate results for further processing. WM natively allows creation of highly customizable toolchains that produce exactly what you need, be it source maps for UE automaterial or separated soil, rock, sediment and flow meshes for external sculpting and smart simplification.
Comprised by a node processing engine and an old fashioned, yet clear GUI, it delivers astonishing results thru recombination of relatively few primitives. Unlike the power hungry competition, WM is relies on CPU-based simulation algorithms. The environment resembles Houdini in its flexibility and a structure deeply tweakable on both coding and visual levels.
In order to flatten a fairly gentle learning curve of the node system, I would recommend adding community-contributed nodes from macro library right after installation. Those come both as black box or editable patches and most of them are, ranging from custom effects and function extensions to ready-made terrain blueprints and export toolchains. Due to the WYSIWYG nature of WM, starting from this “saved games” spares a lot of time by visually conveying standard workflows and best practices.
Image courtesy: Simon Klein