In terms of feasibility, I would try to make a sRGB bitmap that would store per-landscape-section data in each pixel. Height, materials, vegetation, atmosphere per pixel. Then come up with a way for each landscape section to stitch together, and generate more specific landscape details, like rock outcrops and cliff faces (based on the bitmap). Ultimately, it comes down to letting code generate the map for you based on some predefined parameters. Then maybe you can take that generation and sculpt your own touches into it. Would definitely be a project that starts out small.