Hi Paul, who always has tried what I dream about.
I always assumed doing it based on OS maps or whatever in such a way that the model points due north from the start. So there would be no rotating.
What is the remaining issue with exporting track? If can be done now, I read. Never got around trying it, but soon will, hopefully.
The way I see it is this:
I place OS maps decals in World Editor. I fit track to that. I export the result of my matching efforts and load it into Blender (or 3D Crafter in your case). It will be some simple mesh, I keep it separate from the model, "read only" and exclude it from export.
With some luck, I might be able to have Blender lay a Bezier curve along selected edges, or I have to fit is myself. Blender has a nice function that moves a 2D curve along another curve mimicking the RW lofts. But the outcome is converted to a mesh that you can manipulate to your heart's content (or else you could go with a RW loft).
For the texture, you sure need some that tile good. I see some serious work ahead of me in those quarters. What I envision is using two textures, inverse to how people put ambient occlusion shadows on their buildings: Texture 1 is coarse and untiled. You paint the base colour of, say, the street on it. The second is fine-grained and tiling and it only shows the outline of the stones that form the pavement of the street.
I believe I could get texture 2 by subtracting a texture from its very blurred copy. Or(and) by desaturating it completely and maybe applying some histogram curve to it. The thing is: All photos are a bit different in hue and/or brightness on their edges. So if I get "the dark lines" out of a photo, it might be easier to make those really uniform. The area between them will be transparent and the dark lines may have an alpha value well under 1 so the base colour from texture 2 has a chance to shine through.
Where I say "dark lines" in less easy cases it can also be lines in other colours, like mortar between bricks. That that will be harder, because the above advantage of working on shades of gray is lost. Mayby doing that and adding in the colour of the mortar in the end can help.
In theory, you could have a bump map instead of texture 2, but I guess it would be wasteful.
Now if I have one mesh that is nothing but street, all that is left to do is the orientation of the stone patterns. Which can keep you busy if you are like you and me.
But if I want to save on draw calls, I need to integrate pavement with grass and maybe some wall. One way to do that could be to have a side ratio of 1:2 for the fine-grained texture, maybe even 1:4. I searched the net for confirmations about that being inferior to 1:1 but could not find much outside phone games.
So assume you have one texture that tiles to one direction and has a few stripes for 2 to 4 different types of ground structure. And another one where I can paint (using Blender's texture paint) rather simple colours that I lift directly from photos. Sounds sexy. But I still have not found a way to clone myself, and my wife would not allow it, one instance is enough trouble, she says.