Terrain & matter generation?

Hi there, I'm looking for tools for generating terrains.

I'm quite new to this, and I checked a https://www.world-machine.com & other https://quadspinner.com (only for windows) and they look very interesting, especially as they can export for OBJ, heightmap etc.

Actually, the process would be:
- generation - export to obj
- pre-calculation of path inside the maze of valleys & holes and whatever
- import the mess in max and move camera around these pre-calculated path and visualize the terrain.

I'm also interested in visualizing the terrains as very hi-res with basic shader rendering (shadows, etc). Just still frame.

Would you have some softwares or advices around this?

Any ideas would be appreciated :-)

Thanks