Shadows on a displaced surface are very low res + fading in & out

Development Rendering
1

Hey guys,

Had a person using the community ocean project mention the poor shadow quality that jump/shimmer and fade in/out. It’s difficult to explain so I made a quick video:

As you can see from the video, when in editor mode the shadows are low res but don’t show any of the artifacting present when you play/simulate. While playing/simulating the shadows seem to fade in/out, shimmering isn’t the right word but it has that kind of effect where the shadows are quite jumpy.

The lighting is 100% dynamic using a single Directional Light and a Skylight. On the directional light under the Cascaded Shadow Maps section I have increased the Dynamic Shadow Cascades to 4 in order to get the best quality possible. Dynamic shadows are enabled on the ocean mesh, I’ve tried enabling/disabling and adjusting every setting I could find but nothing seems to improve it even by a small amount. The ocean plane mesh is not scaled in editor and has a proper lightmap setup.

On the ocean plane mesh I increased the Lightmap Resolution to 4096 (from 64), and did the same on the tree/ship/other objects just to test whether it would make a difference, but I can’t see anything noticeable. Another test was to create a basic opaque material with a panning normal map to see if this was something to do with translucent surfaces, but it seems to be the same there too. Also tried disabling TemporalAA, which barely helps with the fuzziness (low res), but it isn’t really an option for this or other users projects.

Is this a limitation of the engine or can it be fixed?

Thanks in advance for your help

2

.unrealengine.com/en-us/Engine/Rendering/LightingAndShadows/LitTranslucency

3

As I mentioned above:

This is also present on opaque materials.

Is there something in particular you are trying to point me too in the documentation?

4

and

Do not tag along very well.

If that is baked lighting, which it looks like, its combination with cascaded shadows and WPO and/or displacement could produce something like on the video.

5

Hey ,

Yeah I should have just edited that last part out, realized not long after posting that messing with lightmaps made no sense in our situation.

ForceNoPrecomputedLighting is enabled in Global settings so it is 100% dynamic, and the light source is rotating with TOD. That must be why it’s fine in editor and only shows up during play. So basically moving shadows on a moving surface…

Any ideas how you would go about it? I need to keep the rotating sun, it’s just a basic implementation in blueprint, however I did test it with the more accurate version in the plugin as well and both seemed to be identical (both on Tick).

6

Yeah, that makes perfect sense now.

Usually this effect ranges from unnoticeable to insignificant.
The higher shadow buffer resolution is and the filter size, the less noticeable it is.

Consider rotating the light at larger increments, but less frequently.

Also, whole thing seems too low res for a 4-cascade scene