RF1 tracks are usually quite low poly and yes, very "smooth" or alternatelingly very rough from too little poly's. No idea what 3d application you are using, but, if its Blender, I usually:
1. Merge all the road meshes and immediately bordering roadside meshes into one mesh (ctrl-j to join, in edit mode, mesh/cleanup/mergebydistance)
2. Rename to "1ROAD_Physical_Mesh", CTRL-I to invert selection, and delete everything else)
3. In edit mode, Tri-to-quad, then subdivide to taste, usually once is oneough, if really old track, twice or more.
4. Smooth laplacian a few times to correct chunky joins
5. Now the magic bit, edit mode, select Mesh/Transform/Randomise
(tweak the popup setting tools to taste, in this case ~0.0002)
6. Object mode, in the mesh properties, lift the mesh 0.0003 upwards.
7. Export fbx, in kseditor set IsRenderable property to false, save KN5
(depending on how bad the import was if you used 3dsimed, you may want to use the purgetool first to clean out all the dissasociated textures it creates, they will make this file far larger than it needs to be and also kill FPS)
8. Load the physical mesh in your models.ini file. (so if you dont like it your original track is not screwed up)
ONCE you happy, and cars dont float (reduce number in step 6 if they do),
9. convert the quads back to triangular mesh, using the mesh rebuild modifier, will add a good shot of extra randomness as it tries to minimise mesh size.
10 In original track remove the naming 1ROAD from any of the underneath parts, just in case the poke though causing jolts, i usually name them VisibleRoadMesh, save out the KN5.
I did this with this track to add some roadfeel back into it, works well. dont overdo the randomise tool, it should be very subtle, also the more you subdivide before the better the effect, but eventually mesh will get quite large.
In game all your original geometry remains visible, no changes the car simply drives on an invisible mesh.
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