Speed Tree LOD distance settings?

Hey all,

So I purchased the UE4 Mobile package from the speed tree store and I’m trying to adjust the LOD distances. By default they switch to the next LOD far too early. The only thing I can see to adjust the LOD distance is the Screen Size setting. I tried making the default numbers 5x larger and that seemed to do the opposite of what I wanted so I then divided them by 5 and it seemed to work for a bit then I adjusted my start and end cull distance numbers in the Foliage instance settings and now the trees are back to switching LODs too quickly.

Could someone please explain how to adjust the LOD distances and what values should be used for the Screen Size (they’re really small by default). Is there a math equation to translate the Screen Size number to Unreal units?


It’s very simple- screen size is how big the asset will be on screen before switching to the next lod. There is no formula.

What I personally do is start on lod 0, back the camera out until I don’t notice gains from more polys. Then I enter that number in 0 &1. Now I zoom out more. Repeat process, enter the next number.

Thanks for the reply TimeSpirit,
I think you’re talking about inside the Speed Tree editor as I remember this from UDK. Sadly I purchased the trees as a plug and play package and don’t have access to the editor as I haven’t subscribed. After a lot more searching, I came across this article which explained what the screen size meant.

The problem I’m having is understanding which LODS need what value. For example you said that you enter that number into both 0 and 1. I thought by doing that you’d skip an LOD level because the tree would be (for example) 1% of the screen size at X distance away and then it would swap to LOD 1 at which point as soon as you move back a few step LOD 1 would be less than 1% and it would drop immediately to LOD 2.

Wouldn’t it be better to have an even distribution between the LODs? For example LOD 0= 0.1 (10%) LOD 1= 0.01 (1%) and LOD 2= 0.001 (0.1%) ?
That’s what I was attempting in the first place, but I think I was simply going too small for LOD 2.

When you open up the properties of a static mesh in UE4, in the upper corner a number will appear next to screen space. If you zoom out, that number will change. You use these numbers as a guide to tell the LOD’s when to switch to the next one.

Every asset is different, some assets with relatively the same size can share LOD settings. I find for best results you will want to zoom in and out and see how the transitions work for you.

Oh crazy. I never noticed the numbers in UE4 thank you.

Is there a way to disable a specific LOD level? just type zero or?