[UE 5.1] Poor quality of low angle lighting

I learn using static light sources and baked lighting. I have an issue when a Directional Light source [Mobility = Static] gives a “stairs effect” on the enlighted surface. (see screenshot below)
Shadow Bias = 1: UE5_Question-Rendering_Light_Poor-quality-of-low-angle-lig… | Flickr
Shadow Bias = 0: UE5_Question-Rendering_Light_Poor-quality-of-low-angle-lig… | Flickr

I’ve already tried:

  • changing parameters at [Directional Light → Details] (all, one-by-one)
  • changing parameters at [PostProcessVolume → Details → Lumen]
  • increased objects’ [CubeN → Details → Lighting → Overriden Light Map Res to 1024] parameter
  • increased both objects’ [CubeN → Edit Mesh → Details → General Settings → Light Map Res] to 128
  • switched between [Project Settings → Engine → Rendering → Shadows → Shadow Map Method] = Shadow Maps and = Virtual Shadow Maps (Beta)

However, any of these options does not help me increase the number of these “stairs” or light calculation steps, as I assume. Please, help me increase the quality of the low-angle light or smoothen these stairs (without using [Directional Light → Shadow Bias] parameter)

  • Why don’t I use Shadow Bias? Because increasing Shadow Bias parameter gives a “light leak” artefact between the walls of the interior.