Hello,
I created a landscape and noticed at a very specific place a mesh deformation (you need to look well but it is there) and consequently the UV map is moving which is very visible.
You can see the effect in the small video here:
What could be reason ?
Any solution ?
Thanks 
If I set the LOD to 0 instead of -1, I do not have this deformation, but the landscape becomes “ugly”
I have different levels of “river beds” like that and the issue only happens at this place.
You can increase the geometry of your landscape by going into :- Landscape > Manage > Resize- And change your resolution there but make sure you change the type to re-sample and not resize.
This is what happens when you have “too steep” changes. It’s because of the subdivision of the landscape. It’s pretty coarse, for performance reasons.
Run a quick “smooth” brush over a few of the surrounding vertices, and the artifact will improve.
If you need higher resolution, you can either model the geometry in an external tool (You can even use Nanite!) or you can change the Scale of your terrain to something smaller, like 10 (it defaults to 100) at a significant increase in geometry cost, and needing to re-do your materials.
Thanks for the answers.
I resculpted/flattened/smoothed this area, but I still see the effect.
I have the feeling it is even worse as now I see it on the top part of the bed in the vicinity of this area (maybe it was already there and I did not notice it).
Anyway I’m following a landscape creation tutorial and not really creating a game, so I will skip this and move on in the tutorial as I want to progress.
Could you draw a ring around where you think the problem is in this picture?
Is it the fact that the “square” material is distorted? That’s what you get with orthogonal UV projection. To fully fix that, you need to use a volumetric landscape material, which can look great for rock/dirt type surfaces, but generally don’t work well at all for grass and other ground vegetation.
