So, as I said many times. Data is data. So long as you have the data you can do anything with it.
In the case of splines you need a few mathematical operations to occur.
I reccomend you extract just one road to start/test.
Also, as painful at it is each road should really be its own spline anyway.
With the extracted vertex data you need to output the longitude and latitude of the vertex that makenup the street.
you can do this by modyfying the properties and adding in the proper code.
it should bring you to a topic with the rest of the code - which I don’t remeber by hart.
Having extracted the data here you should probably (but it isnt required) get the Z position in there as well.
to do this you can look into the Point Sampling Tool plugin.
Having a generated dataset with x,y,and z, you can save a CSV file and work in Excel to produce the appropriate world bound coordinates.
Thats a bit of a topic on itself, but you map that got put into unreal is a slice of the DTM with a precise Extent.
the extent value in Qugis is in Lon/Lat notation - so you have to convert to unreal units to get the proper data in.
In essence you get the ratio of the extent vs unreal, and with that you calculate what a longitude/latitude coordinates actually mean within unreal.
Its fairly simple math mind you. Excel just… excels at allowing you to create a new sheet with only the data you need for export.
Once you get the print out, copy and past the values into a new Excel doc. Save as CSV, and import into the engine.
Then all you have to do is create a bluepring that modifies a selected spline by adding in the points.
I’m on mobile or I’d give you the link, but the base on how this is done is a 3 or 4 year old live training video. The system really hasn’t changed all that much.
running the blutility script you create based on that, you will generate the selected road spline.
use another blueprint that contains a spline btw, so that you can modify things like the mesh, or add a bluetility action to displace the terrain with this spline.
Assuming you did all of that with world Z, the points generated by the process should be more or less exact.
If they aren’t, you can right click one of the spline points, select all the spline controls, drag them up above the terrain and hit the End key to get them flat on the terrain (also why I said you could skip the world Z part).
Thats the gist of it.
Start with a small road with a max of 10 vertex to make sure that both the data calculations - which are easier to tell considering you already have buildings in place - are correct.
and that the generation scrip works as intended - since you will need to modify what the tutorial provides quite a bit.