I’m looking into the best process for importing or otherwise laying down a large road system within UE4 (potentially up to 10k sq. city-scape).
I’m thinking the best way would be to have an illustrator file (or something similar) with the road layout (colour coded based on road type). But not sure whether there is any process I could go through to import that and make use of it in-engine (beyond putting it on a large plane and manually placing road splines on top).
Anyone had any experience with something along these lines?
Is it a flat surface or elevated landscape? If it is a flat surface you could bring the road meshes into the editor without needing splines. Otherwise you can bring the layout of the roads as a texture, apply that texture to the landscape and then draw the roads manually with either landscape splines or BP splines, following that layout.
It’d be a mostly flat surface. With an area this large, I’m guessing the only way to pull it off would be to split up the road models into one mesh per road segment? Anything more than a couple of streets in one mesh would end up being extremely large.
I’m still toying with how to process the data I currently have of this city.
How you want to split it up also depends on how detailed the mesh is. How many polygons is the whole road mesh or the road meshes in total if it isnt a single mesh?
I’m looking at about 6-8 polygons across and anywhere from 1 to 50 polygons in length. So road segments would be around 250-500 polygons per mesh. All road meshes would share the same material (3x 2048 texture maps). With the map area I’m looking at at the moment, there would be around 6,000 streets. So we’re looking at around 3 million polygons for the road structure alone. However the city (Paris) has a lot of straight roads, so this number might be closer to 2-3 million.
Is there an upper limit for single mesh imports? I also worry about how collision for something this large would function.
Oh ok, it wont work out as a single mesh then. You can import a 3 mil. polygon mesh into the editor(though it will take some time) but it wouldnt be practical to use it. Because it is a single mesh you would have to render 3mil. poly’s all the time without culling and performance-wise that wouldnt leave you much room to put other things into your level. So you’ll have to split it into several pieces. As to the collision, it is not a concern since you can use per poly collision.