Apseren Industries has released a terrain generator that uses a neural network trained on handmade 3D models. Features include the ability to change the detail of each terrain, the ability to smooth terrain, a low poly mode, an option to voxelize the terrain, the ability to add edges to terrains to simulate the ground below them, and the ability to convert the output to a Unity terrain, and more. ML Terraform is available as a browser-based tool and a Unity Asset. Try it and find out more.
