@Valentin5C40
I heard back from the engineering team — this is a resolution issue with the shadow casting box. Here's what's happening: shadows in Advanced 3D are calculated within a bounding "casting box." That box has a fixed shadow-map resolution, so if the box is large, the resolution spreads thin and shadows step/jitter as objects move.
The fix is to shrink the casting box so it covers only the shadow-casting geometry, not the whole scene. Here's how:
- Hide everything except the pink rectangles (the actual shadow casters).
- In the renderer settings, click "Fit to scene". This shrinks the casting box to the exact dimensions of the visible geometry.
- Unhide the rest of your scene.
One counter-intuitive detail worth calling out: the casting box only needs to include the objects that are casting shadows, not the surfaces the shadows are landing on. So a small box around your rectangles is fine even if your ground plane extends much further.
Give that a try and let me know how it looks.
Thanks,
Nishu