Strange culling behavior - Foliage

gestoryscht · April 19, 2018, 1:54pm

Hi guys,
I have big problems with the performance of my scene. Usually, it runs with 100fps in an average, but when I look on the whole scene it shrinks down to 10 fps. The problem is the grass. When I hide it, everything is fine.

The culling doesn’t work properly. The cull distance is measured in Unreal Units, right? Well, I set it to 1 unit (1cm) and the grass in the back disappear. Well, fair enough, this is what I thought would happen … but the grass in the foreground is still visible.

After zooming out - several meters - the grass disappears.What could cause this and what could be a solution here?
And here, this is pretty ‘good’ culling. Some grass clusters didn’t even disappear even after 20000 units.

Thanks for your help!

Xaith · April 19, 2018, 1:57pm

You are probably having LOD problems. I believe your solution is in here: Foliage brush and LOD meshes - Content Creation - Unreal Engine Forums

gestoryscht · April 20, 2018, 7:18am

Thanks for the fast reply, but no. This doesn’t work
I imported a whole new Mesh and replaced it in the foliage tool with the new one. No change.
Actually, I do not have a LOD Ground assigned - so this isn’t the problem.

gestoryscht · April 20, 2018, 1:01pm

Okay okay, it’s definitely the grass mesh, but I do not know why, to be honest. I created a new map (in the same project) and placed some grass patches. The same problem - I replaced the mesh with one of my crate mesh and it works perfectly. Now I have to get a clue what is wrong here ^^

I will be back soon with more information.

EDIT: For me, this is a bug.
In case it isn’t, please explain me this behavior:

First screenshot. I’ve painted some grass with the fresh imported grass.
Culling doesn’t work (well, it works, but with the described problems).

Second screenshot. I switched the mesh. Culling works as expected.

Third screenshot. I switched back and et voila … it works for some time. After tabbing onto the desktop and back it’s broken like before. It’s wonderful _

gestoryscht · April 20, 2018, 1:35pm

It is definitely a bug - my project is broken. I started a completely new project and placed everything there. It works perfectly.

Now I have to transfer everything into a new project … I hope this is even possible

Velrin · April 20, 2018, 1:58pm

Check the bounding box on the grass mesh. Make sure its properly covering the whole mesh.

gestoryscht · April 20, 2018, 2:07pm

This is how it should look right?

Velrin · April 20, 2018, 2:09pm

Yeah, that’s correct.

gestoryscht · April 20, 2018, 2:49pm

Thanks for your effort - I really appreciate it.
Could you send me a PM? I can’t find the button - I just see the ‘follow’ button. Thanks!

Ohhh and please take a look at the file I’ve posted. I think my UE is totally broken now. I created several new projects and in the first place, it works and then it ‘crashes’. Now after the seventh project I’ve made, nothing works at all… wow.

EDIT: I’ll upload the video elsewhere.

EDIT2: Unreal Engine - Strange culling behavior - YouTube

Xaith · April 20, 2018, 2:21pm

It’s probably a setting somewhere? It’s often something simple that was overlooked. I’ll look into this a bit more as well just so I know more. If you are unable to transfer your project info. or if you want to try o to fix the issue in your current project, send me a PM, I’ll try to help.

gestoryscht · April 23, 2018, 8:40am

Okay, an update.
Now, after setting Dithered LODs to true in the material panel per hand, the dithering works … BUT there is no change in the performance. Everything is still laggy as hell.

I’ve set the culling distance to 1, so no grass is drawn. FPS is still low.
After hiding the whole grass instance, the performance goes to around 100fps.

Visually it’s the same. In both version the grass is not rendered, but with culling there is no performance difference.
Still buggy … it seems, the foliage is still in the memory…