Unusually Jittering Trees, Unreal 5.4

[SirJackson]

Hi all,

I hope this is the right place to post this.

Currently I am facing an issue where the trees from two different artists painted using the foliage painter, have jittering issues on one side of the landscape, but on the other side they work completely fine.

Some things to know:

• Nanite is not enabled on the trees
• This test is done on the default open world map
• Happens with foliage painter
• Also happens with PCG spawn static mesh node
• If the static mesh itself is dragged into the scene, it works fine from anywhere

It always (in my testing) affects the InstancedFoliageActors with any negative number in their name, so for example:

InstancedFoliageActor_3_-3_0 (has jitter)
InstancedFoliageActor_1_1_0 (doesn’t have jitter)

This issue appears to be related to the world position offset. Please refer to the video below:

Example WPO

I have searched for solution for quite a while now and I cannot find one at all, so any help would be appreciated.

SOLVED:

Run the object position node through a TransformPosition node like so:

[Astrotronic]

Hello Jackson,

It might be helpful to post the material graph, someone might notice an error in the WPO implementation.

Also, I’d start by getting more scientific to determine how it’s breaking. For example, if you paint one at the origin, and then 1 in each direction, do they jitter in certain ways based on which axis they are painted in?

Foliage painter is creating Instanced Static Meshes, (as opposed to the regular static meshes you mentioned work 100%) so that should also be a troubleshooting consideration.

[SirJackson]

Hi,

Sorry about that, I tried to add as much description as I can, I have added the WPO from the graph and some more info. I will continue to expand the post as I do more testing.

Thanks!

[Astrotronic]

Thanks for that.

I’m noticing some unexpected behavior with that ‘Object Position’ node.

That’s 3 static meshes above, each with their own coordinates, then when painted everything shares 1 set of numbers.

A search for “unreal engine object position foliage” returns a lot of results.

I just tried again passing that node through a ‘VertexInterpolator’ node and it looks to work as expected.

Let us know how it goes!

[SirJackson]

Wow! Thank you so much, I couldn’t get the “VertexInterpolator” route working, but you were spot on about the object position node. So I managed to get it working like so:

By running it through a TransformPosition node.

Hope this helps someone else in the future

Once again, really appreciate the help as I don’t tend to work with materials often as I am a C++ gameplay programmer and I would have never got it without your help!