Tessellation issues within unreal 4

JamieMcAndrew

Hi all,

I am having an issue with tessellation in Unreal 4. I am relatively new to the engine so go easy on me.

This is the first issue i have come across:


The mesh that this texture is on was built in engine with the UE4 Terrain generator and these gaps seem to appear at the chunk borders (i hope that makes sense). All the texture maps that i am using are tillable. 



The second issue i am having is that at distance, some of the terrain appears to be disappearing,l the mesh itself is still there but some of it is no longer displaying. If i turn off the tessellation and the displacement the issue persists.

This is the material that i am using:


Anyone got any idea what i can do to avoid or over come these issues? Any help would be great.

Thanks

Obscura

Enable "crack free displacement" in the tessellation settings, and set maximum displacement to a high value. If things still disappear, you may need to adjust the bound scale of the mesh.

JamieMcAndrew

Thanks for the reply,
I have upped the max displacement amount (it was on 0 and i upped it to 2), but this seems to have reversed the problem. So when i am close with the viewport camera the landscape disappears and when i am further away the landscape is there. 

Obscura

You should set it to a bigger number. at least the same as whats your displacement value. if things diseppears, increase the bound scale of the mesh.

JamieMcAndrew

how do i change the bound scale of a mesh? sorry new to the engine

Obscura

You can change it on a per instance basis. You'd to that by just putting the mesh into the level, selecting it, and on its properties, there is bound scale. Or you could open it up with the static mesh editor, and set it there. Then it would have the altered bound scale by default.

Obscura

Ah I just realized its a landscape actor, sorry. Then the bound thing won't do much. This should not happen. Is your tessellation method set to pn triangles?

JamieMcAndrew

PN Triangles are on.
I have just turned wire frame to see if anything funky is going on and found that the wireframe is also not displaying around the camera, but is further away.

Obscura

Okay so I took a look at your material, and you are multiplying the vertex normals ws with some value so you bend the normal direction. This could be the reason for why is it floating further. You should put that multiply after sampling the texture and then multiply that by the vertex normal direction. If that still doesn't give you good results, instead of using the vertex normals, you can try using up direction.

JamieMcAndrew

ok awesome thanks very much for the help, im not current in a position to work on this but i will be tomorrow so i will let you know how things go

JamieMcAndrew

ok so if i have understood you correctly this is what you meant by moving the vertex normal bend till later.


I probably should add that this is happening in both the viewport and in game view

JamieMcAndrew

 So i rebuilt my lighting as i haven't done that in a long time and this seems to have fixed the problem that i am having, thanks so much for the help you have provided. I do still seem to have cracks on the landscape with displacement though, i have turned on crack free displacement and have made sure that the maps i am using are perfectly tiling. Not really too bothered about this for now though. At least i can see the landscape now.

Thanks again.