Enlighten Lightmapping with large scenes (square kilometers)

Unity Engine
1

Hi all,

I am working on a large scene project (city-scaled between 5 and 10 square kilometers). Everything fits in a x250 scaled Unity plane (so 2500 m x 2500 m).
In Unity 4 (Beast), lightmapping takes 20 minutes with reasonables settings.
In Unity 5 (Enlighten), lightmapping takes 48 hours !

I know from the discussions around that Enlighten is not that optimized when we deal only with static baking.
Is there anything I can do ? (apart fro crying…)
I tried all the settings, I tried to split my objects in smaller ones, and nothing works.
The only thing that “works” is to scale down the whole scene

A very simple test is to lightmap a simple x250 plane with a single directional light :
-Beast : 20 seconds.
-Enlighten : 23 minutes ! Hello “7/11 Light Transport !”
:frowning:

Thanks for any hints !

2

Why would you want to lightmap a 2500 unity plane anyway? I’m not sure any game in history has done this, so why are you? The shadow resolution would be tiny. Most games would make the terrain vertex lit.

3

This is a city with streets, buildings, surfaces, objects. The plane is only a “fallback ground” in case of holes in my surfaces. And yes, I know that resolution would be tiny (less than 1 pixel/m), but still enough for ambient occlusion and GI to add realism.

4

tried the progressive lightmapper?

5

Enlighten is 10-100 x faster when using VeryLow Preset
It’s fast enough (faster than PLM )