Decrease light build times with level stream

I have expanded my level with some landscapes and the light build times are taking around 20 to 30 minutes. I have included light map importance volumes as well, and the level still takes around the same amount of time. What would be the best way to proceed in reducing that time and is there anyway I can perform level streaming even though the landscapes were all added to the same map and not as separate levels?

Thanks and looking forward to hearing back

how much ram ya got? also if you turn off any shadows that arent neccessary i noticed that can help. Also, changing the lightmass resolution on static mesh actors can help too. Lighting in unreal generally takes forever though. Ive seen projects where it takes hours. in case your new to unreal and dont know, you can test your game by just pressing play, a lot of times building is unnecessary

Hey MS2013,

To add to ViceVersa’s information, there are a number of ways to decrease lightmap build times, but at a certain point it comes down to your computers hardware (graphics card, ram, and processor), as well as the density and scale of what you are trying to bake with Lightmass.

One location to look is the ‘World Settings’ tab. This tab contains a section which you can expand called ‘Lightmass.’ Here there are various options to choose to change the way your Lightmass calculates and accounts for different variables. Take a look at this section and hover your mouse over the options to read the tooltip for information on what the settings does and what it effects. Another way to decrease lightmass build times is to reduce the overall lighting quality. If you are constantly making changes and have short iteration times when baking your lights, set the quality to something like ‘Preview’ or ‘Medium’, just to get the general feel and point across. Switch back to ‘Production’ for your final lightmass build.

Below is a Lighting Troubleshooting Guide which contains A LOT of helpful information, including the settings mentioned within the ‘World Settings’ tab.

Lighting Troubleshooting Guide


Thanks and ViceVersa for all the helpful info. I will definitely try changing the settings in the world settings lightmass tab. My current lighting build setting is at preview and it takes the 20 to 30 minutes. The engine scale is set to epic though, but I don’t think that’s too important considering i have my build at preview.

I’m using foliage from the unreal open world demo, but other than those, the static mesh’s in the level are created by me and I have set the min Lightmap Res to 64. Is that alright?

Currently my laptop is an i7 with a GTX 960 and 16GB of ram. Is it normal for landscapes to have longer build times? Also I have attached two screenshots of my level to show the relative scale of the landscapes. I just want to be sure I can continue adding more landscapes without having to worry about level streaming and world composition. If so, could you please explain how I would implement this? I tried understanding and following the documentation and tutorials, but I cannot seem to understand how to implement it in my specific project.

Thanks guys for the help!

I should also mention that I have level streaming enabled from the settings tab so certain things may seem blurry because of the way i have set the viewport settings.