Why does my light build take so long and crash after a while?

Why does it take so long to build, it takes about 40 mins for 3% and then it crash? Im converting all my buildings from bsp to mesh because i got a problem with them last month that they went invisible and i have converted half so far after a longer break and now when i try to build it just crashes so please help.

the ground will be bsp.

Is your lightsource set to stationary? Try to increase your virtual memory and ram memory

i have 16 gb of ram and my lightsources are set to stationary.

What is the lightmap size? Do you have a light importance value?

Those 2 can affect build time quite long. Try lowering the lightmap size, setting the light quality to preview and adding a lightmassimportant to the scene. Should be quicker. If it doesn’t help, could you post the error log?

thanks for the help but i think i restart from the beginning because i found more problem so i think i have done someting wrong with the save but thanks.

I have been using the engine for a very long time now. Right now I a battling with 1 City block -like you- I have a light importance volume. Most of my foliage is independent light mass at 8. My landscape has 1 hill and there is one point light and 3 spot lights.

It has taken over 4 hours to build lighting…

I am pretty much awestruck.

I have also made sure my lightmass settings were low and changed my static lighting level scale to 4 in hopes that would speed things up. I just decided to to put the swarm agent on standalone true but that doesn’t seem to be helping… This is crazy there really is no light in my scene… Ray tracing is off… there are no bells or wistles I have one post process in a building with a cubemap to darken it because they can’t seem to fix the interiors being lighter than it is outside…

It is truely unbelievable coming from the people who said a year or so ago that one machine running unreal engine could beat Pixar’s render farm…