Spot Lights may present with very blocky shadow artefacts when a long attentuation radius is provided with a small cone angle. In extreme cases, this causes the VSMs to invalidate every frame. Notably, enabling the visualisation viewmodes for VSMs typically resolves the issue. If the issue does not resolve with a view mode such as clipmap, then the invalidation condition has likely been met and can be confirmed by checking the cache view mode.
Shortening the attentuation radius or increasing the cone angle does resolve the issue, but the issue may occur on values such as 2536 by narrowing the cone further. Other lighting types, such as RectLights, do not exhibit this issue. Setting a rect light to 16384 with a very small size still provides non-blocky shadows.
Expected: Normal VSM-type shadows from the sphere
Actual: Blocky shadows akin to very low resolution shadows.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-290280 in the post.
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Component | UE - Graphics Features - Shadows |
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Affects Versions | 5.4, 5.5, 5.6 |
Created | May 26, 2025 |
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Updated | May 26, 2025 |