Accurate velocities from vertex deformation
The above is a wonderful example of how great vegetation foliage can look in UE4. The above forest valley scene is by Douglas Davis.
The rest of his amazing work can be found here:
https://www.artstation.com/artwork/gaQoZ
So, this is just a quick one as it's something that I keep having to come back to but strangely not many people know about it. When adding foliage into a scene you often get a strange morphing movement effect. The first reaction is to think the animation or frame rate is to blame, but usually, this is being caused by the temporal anti-aliasing (TAA).
This happens when using masked material with vertex animation as the temporal anti-aliasing reuses results from past frames and blends them together
It needs a sort of history buffer with anticipation of where it will move next to have fewer artefacts.
This can be achieved through the use of motion vectors.
Open Project settings, Rendering, and then Optimizations. Find the tick box for Accurate velocities from vertex deformation and select it.
After a restart, your foliage movement will look more natural but this will incur a performance cost.
Epic uses this in the Kite demo and it looks amazing. Try it yourself and turn it off. It certainly makes a difference!
This was also covered in the Unreal 4 Lighting Academy Session 3.33 by 51Daedalus. Thank you!
https://www.youtube.com/watch?v=SVHj2HXAFfw&t=2s