Mapping vector sprites on 3d terrain? Is there a (better) solution?

Hi,
for a GTA1 like game, I extracted the OpenStreetMap information about the streets, parks,.... of a city by converting it into different vector sprites. With sprite masks I can now generate streets, sidewalks, parks, water,.. precisely without huge complications.


(the textures are S***, but the workflow with sprite mask and vector sprites worked for me)

Now I realized that my game needs to be in 3d and I started to implement terrain.

And now my problem: I can't find a solution how I can use the accurate vector sprite or something similar to map this on the terrain. I can use a splat map but this leads to huge splat maps with still pixelated edges and an awful workflow.


(pixelated edges and huge splat maps with an awful workflow)

Does anyone have some good ideas how to handle this? I have no experience with shaders and I'm afraid of starting "to write my own shader" with the hope that this could solve the problem.

Thanks in advance!