Light Propagation Volume + Additive Blending

Hello. I’m trying to achieve this look:

Specifically, the traffic streaks via timelapse photography. Note the lights from the road/cars hitting the sides of buildings.

I’m doing this with Light Propagation Volumes. I know this feature is experimental, but still, it looks awesome.

I got it more or less working:

However, it looks bad. The non-lit areas are black, covering the road. When I stack traffic paths on top of each other, z-fighting happens. What I really want is to have this be additive, like so:

This looks great! BUT: As you can see, LPV does not activate here. How can I achieve both?

One possible solution is to have two versions of this mesh, one that’s emissive and one that’s additive. However, I can’t make the emissive one invisible without also having LPV turned off.

Any ideas on how I can do this? Thanks :slight_smile:

Have you considered simply placing the emissive objects underneath the road?

that’s a cool concept OP, can’t wait to see the completed image.

How about just using a skylight and some ambient occlusion instead of LPV? The geometry is very basic and you don’t have any interior. You could fake G.I pretty easily imo.
Or use point lights carefully placed all around the map.