# Ray Traced Shadows Dont Work With World Position Offset on Instanced Static Mesh or Foliage

**URL:** <https://forums.unrealengine.com/t/ray-traced-shadows-dont-work-with-world-position-offset-on-instanced-static-mesh-or-foliage/465184>\
**Category:** Rendering\
**Tags:** Shadows, Reflections, unreal-engine, Instanced-Mesh, Ray-Tracing, Foliage, question\
**Created:** [May 14, 2020, 2:11pm UTC](https://forums.unrealengine.com/t/ray-traced-shadows-dont-work-with-world-position-offset-on-instanced-static-mesh-or-foliage/465184 "2020-05-14T14:11:37Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![OptimisticMonkey](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/optimisticmonkey/32/906571_2.png) [@OptimisticMonkey](https://forums.unrealengine.com/u/OptimisticMonkey)\
**Post date:** [May 14, 2020, 2:11pm UTC](https://forums.unrealengine.com/t/ray-traced-shadows-dont-work-with-world-position-offset-on-instanced-static-mesh-or-foliage/465184/1 "2020-05-14T14:11:37Z")

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WorldPositionOffset works for Ray Traced Shadows/Reflections on a static mesh. (Have to check Evaluate World Position Offset in mesh rendering section).

However, using that mesh in an Instanced Static Mesh or as Foliage breaks ray traced shadows and reflections. (They dont take into account the WPO )

This is critical for foliage that uses wind among other effects.

Much thanks for any feedback / help with this

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**Author:** ![flat4ers](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@flat4ers](https://forums.unrealengine.com/u/flat4ers)\
**Post date:** [June 2, 2020, 12:50am UTC](https://forums.unrealengine.com/t/ray-traced-shadows-dont-work-with-world-position-offset-on-instanced-static-mesh-or-foliage/465184/2 "2020-06-02T00:50:51Z")

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Same problem.  
May be add WPO for Foliage later… idk  
or fix double mesh bug on foliage.  
For me will be OK moving grass (for example) with static raytracing shadow, but now this double mesh effect look creepy.

i tried used HDA for instancing grass mesh, but was similar problem.

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**Author:** ![Tabacudo](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Tabacudo](https://forums.unrealengine.com/u/Tabacudo)\
**Post date:** [September 22, 2020, 9:06pm UTC](https://forums.unrealengine.com/t/ray-traced-shadows-dont-work-with-world-position-offset-on-instanced-static-mesh-or-foliage/465184/3 "2020-09-22T21:06:55Z")

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Same here. I’m having this duplicated mesh, one stays static and the other is moving. Weird as hell.

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**Author:** ![Yondr](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Yondr](https://forums.unrealengine.com/u/Yondr)\
**Post date:** [February 27, 2021, 3:40pm UTC](https://forums.unrealengine.com/t/ray-traced-shadows-dont-work-with-world-position-offset-on-instanced-static-mesh-or-foliage/465184/4 "2021-02-27T15:40:36Z")

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Same. There is r.RayTrasing.Geometry.InstansedStaticMeshes.EvalueteWPO (nvrtx4.6). But I guess there should be some right way to fix it.

Another answer I have found: “ Try foliage actor to painting foliage it works great. For grass you need use foliage procedural volume.”

> **[Why does foliage wind effect appear weird when raytracing translucency is...](https://forums.unrealengine.com/questions/994309/why-does-foliage-wind-effect-appear-weird-when-ray.html)**
>
> Whenever i turn on Raytracing translucency, the wind effect in foliage starts to appear in doubles like in this gif. And when i turn on “EVALUATE WORLD POSITION OFFSET” it gets normal. But that option is not available for Painted foliage actors. But...