Actually, the speedtree LODs bug. With custum Screen Size, each time UE4 restarts or a level loads, the LODs don’t work fine. It’s necessary to update the Screen Size of LOD0 (to retape the same value) to correct temporaly the bug:
Without update:
With update:
Hi Shinje,
If you try using higher values does everything function correctly? I believe you may be running into a similar issue that was happening with this user LOD Screen Size Unchangeable - Asset Creation - Epic Developer Community Forums
Anything below a value of 0.01 gets clamped to 0 and this may be why you’re seeing the settings revert the way they are. If you can use a higher value for your LOD0 and then varying LOD screen sizes for the others you can verify this is happening.
Is there a particular reason to use such a low screen size for your LOD0?
Thanks!
Tim
I’m having a similar issue… - YouTube
Is there a mathematics equation for translating the Screen Size to Unreal units? Or maybe there’s some documentation on how to calculate the proper screen size values?
Its a little confusing that you can’t just enter a distance value for when you want each LOD to start. With the default values that you get when importing a speedtree model, the LODs transition way too close and it looks awful.
P.S. The topic linked above doesn’t exist anymore.
I’ve edited the link above so it actually works. Not sure why it broke. 
No equation for translating distance to screen size. It’s a percent value for it’s screen size. 1 = 100, 0.5 = 50%, 0.1 = 10%.
I’m using the Broadleaf Desktop SpeedTree asset from the free sample pack on their website and cannot get the same results.
Although, looking at your settings you are using invalid values for your lowest LOD. Anything below 0.01 will be clamped to 0.
Thanks Tim. I’ve since sorted this out.
