Introducing TerraRoad - Terragen roads where you want them!
https://github.com/abe-mart/TerraRoadI got tired of not being able to control road placement in Terragen, so I cooked up a Python script to help. TerraRoad combines a heightfield exported from Terragen with an SVG vector path, and produces a new heightfield with the road surface smoothed. It also exports masks that can be used for shading the road, border, and markings, as well as cut and fill areas.
The link above has the Python source code, and install instructions. I believe this should be cross-platform, but I've only tested it on Windows.
There are some limitations. This is heightfield and image based, so you're limited in area and resolution unless you want gigantic files. This is particularly noticeable for closeups of the road lines. They look decent from far away though. The script assumes a single road for now, and no crossroads.
This is early in development, so feedback is welcome and needed. Don't expect a finished product, bugs are expected at this point! A good first test would be to see if I've missed any important steps in the install instructions linked above. I'm open to ideas on how this could be improved as well.