# Volumetric Cloud Tracing Fails on Re-entry and Below the Horizon 

**URL:** <https://forums.unrealengine.com/t/volumetric-cloud-tracing-fails-on-re-entry-and-below-the-horizon/2855749>\
**Category:** Rendering\
**Tags:** unreal-engine, Epic-Pro-Support, question\
**Created:** [October 9, 2026, 3:32pm UTC](https://forums.unrealengine.com/t/volumetric-cloud-tracing-fails-on-re-entry-and-below-the-horizon/2855749 "2026-10-09T15:32:39Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![anonymous-edc](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\
**Post date:** [October 9, 2026, 3:32pm UTC](https://forums.unrealengine.com/t/volumetric-cloud-tracing-fails-on-re-entry-and-below-the-horizon/2855749/1 "2026-10-09T15:32:39Z")

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1. Clouds near the horizon disappear when the camera enters the cloud layer. Rays should continue tracing after exiting and re-entering. This works correctly with alternate mode **Tracing Max Distance Mode: Distance from Point of View**.
2. Clouds below the planet’s atmospheric bottom boundary should be clipped, as the planet occludes them. Instead, they remain visible and can cause bright **Skylight** artifacts, especially at sunset.
3. In **Tracing Max Distance Mode: Distance from Point of View** mode, rays can re-enter the cloud layer, but **UpdateMaterialCloudParam** still samples the conservative density material while outside the cloud hull. Skipping directly to the re-entry point could avoid these unnecessary samples. Ideally, the default tracing mode should also support re-entry.

Screenshot 1 just below the cloud layer showing clouds beyond the planetary horizon remain visible:

 ![HighresScreenshot00000.jpg.jpg](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/f/9/2f99cec189009ba4d0dc7fcb32672e7f789f0fe7.jpeg)

Screenshot 2 just inside the cloud layer showing clouds after the ray exits the cloud volume disappear:

 ![HighresScreenshot00001.jpg.jpg](https://d3kjluh73b9h9o.cloudfront.net/original/4X/3/4/c/34c37551ac57d1d901a0f91a17245ded83af14ae.jpeg)

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<div class="post-metadata">

**Author:** ![anonymous-edc](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\
**Post date:** [October 9, 2026, 3:32pm UTC](https://forums.unrealengine.com/t/volumetric-cloud-tracing-fails-on-re-entry-and-below-the-horizon/2855749/2 "2026-10-09T15:32:43Z")

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**Steps to Reproduce**

1. Create a level with **SkyAtmosphere** , **VolumetricClouds** , and a **Directional Light**.
2. Set the cloud parameters:
  1. **Layer Bottom Altitude** : 2
  2. **Layer Height** : 1
  3. **Tracing Start Max Distance** : 500
  4. **Tracing Max Distance** : 500

3. Position the camera near the bottom of the cloud layer and look toward the horizon.
4. Move the camera upward into the cloud layer.

Alternatively, open **NewerWorld.umap** in the attached project, and you should see the same scene as shown in the screenshots: [https://www.dropbox.com/scl/fi/9smtc29nr2wxs4z1vh214/20261009\_Cloud\_RayIntersection.zip?rlkey\=wvug9xvlojffcxwr1x5p7o3zi\&st\=e9lwo2u6\&dl\=0](https://www.dropbox.com/scl/fi/9smtc29nr2wxs4z1vh214/20261009%5C_Cloud%5C_RayIntersection.zip?rlkey%5C=wvug9xvlojffcxwr1x5p7o3zi%5C&st%5C=e9lwo2u6%5C&dl%5C=0)

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**Author:** ![SebHillaire](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/sebhillaire/32/1194571_2.png) [@SebHillaire](https://forums.unrealengine.com/u/SebHillaire)\
**Post date:** [October 15, 2026, 12:56pm UTC](https://forums.unrealengine.com/t/volumetric-cloud-tracing-fails-on-re-entry-and-below-the-horizon/2855749/3 "2026-10-15T12:56:12Z")

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Hello,

Yes this is as designed.

**Distance from point of view** traces up to the specified _TracingMaxDistance_ from the point of view. You have to tweak the view distance.

**Distance From Cloud Layer Entry Point** : this other mode trace from the first entry point traced from the camera up to the first exit point as I recall. That is an optimisation for point of view on the ground: only spend the tracing sample budget from the entry point into the cloud layer to the exit point. With _TracingMaxDistance_ being the largest distance which in this case can be lower. Re-entry is not supported: that is why the **Distance from point of view** mode was added. If the camera is inside the later, the tracing will be from camera to first exit point, and so due to curvature some clouds can disappear. We do not trace twice.

It seems that you will have to use the **Distance from point of view** mode then.

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<div class="post-metadata">

**Author:** ![anonymous-edc](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\
**Post date:** [October 16, 2026, 9:22am UTC](https://forums.unrealengine.com/t/volumetric-cloud-tracing-fails-on-re-entry-and-below-the-horizon/2855749/4 "2026-10-16T09:22:19Z")

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Hi Sebastian,

Thanks for the explanation and for clarifying the intended behavior.

You can close the ticket.