Using the Geographically Accurate Sun Positioning to animate sun


I’m trying to use the Geographically Accurate Sun Positioning, which is an early access function from 4.21, to animate the Sun’s position in a whole day.
My method is using a blueprint to change the time by adding seconds, as the method in the documentation page.

The issue is while the sun angle is changing, I can see obvious shaking of the shadow edge, and sometimes wired shadow appears on my curtain beside the window, flashing. But when I manually rotate the directional light, the shadow is sharp enough with no shaking.

Any thoughts?


Got response from UDN, for reference if anyone need:

This is related to the resolution of the cascade shadow map (CSM). The default is 2048. I tested as Shadow scalability level 4 (Cinematic) and it was better (4096). I also forced it to 8192 with the r.Shadow.MaxCSMResolution console command and I was even better. Please note that those settings will have an impact on performance.