# Navmesh cracks in irregular geometry such as hills

**URL:** <https://forums.unrealengine.com/t/navmesh-cracks-in-irregular-geometry-such-as-hills/408907>\
**Category:** AI\
**Tags:** ai-navigation, unreal-engine, navmesh, question\
**Created:** [November 6, 2017, 7:48pm UTC](https://forums.unrealengine.com/t/navmesh-cracks-in-irregular-geometry-such-as-hills/408907 "2017-11-06T19:48:42Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![anonymous\_user\_f519f153](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_f519f153](https://forums.unrealengine.com/u/anonymous_user_f519f153)\
**Post date:** [November 6, 2017, 7:48pm UTC](https://forums.unrealengine.com/t/navmesh-cracks-in-irregular-geometry-such-as-hills/408907/1 "2017-11-06T19:48:42Z")

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We are building the NPCs in our game to use the nav mesh for navigation. However, they frequently get stuck on the cracks of navmesh in our level, which largely comprises of hilly and irregular elevation.

Is there any variables or settings we should look into to make sure the navmesh is painted properly with no cracks in them so that the AI could navigate smoothly? For example, is there a setting to know if certain angles or landscape tessellation is illegal for good navmesh generation? Let us know!

In fact, someone else posted this question as well, but it wasn’t answered. 🙂

> **[How can I improve my navmesh for Hills?](https://forums.unrealengine.com/questions/712274/how-can-i-improve-my-navmesh-for-hills.html)**
>
> I have a huge problem. My landscape is rather hilly with quite a few trees and my navmesh is an absolute ugly disaster though for the most part it seems that the AI can navigate fairly decently around the map except for in a few spots I found that...

 ![219323-navmesh-crack.jpg](https://d3kjluh73b9h9o.cloudfront.net/original/4X/7/4/5/745ab0b2dfa4c409a2f4ad2d288c9fe60213c62e.jpeg)

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**Author:** ![Inukshuk07](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Inukshuk07](https://forums.unrealengine.com/u/Inukshuk07)\
**Post date:** [March 18, 2018, 3:25pm UTC](https://forums.unrealengine.com/t/navmesh-cracks-in-irregular-geometry-such-as-hills/408907/2 "2018-03-18T15:25:50Z")

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Hey, I was having the same problem too and after a few tests in the settings I think i have a solution:

In the Recast NavMesh, under the Generation Settings, there is an advanced setting in the drop down portion called Region Partitioning and Layer Partitioning. I changed the default setting to Chunky Monotone on both settings and it eliminated 99% of my NavMesh cracks. Try giving this a shot.

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**Author:** ![HelioHsx](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@HelioHsx](https://forums.unrealengine.com/u/HelioHsx)\
**Post date:** [September 11, 2026, 5:31pm UTC](https://forums.unrealengine.com/t/navmesh-cracks-in-irregular-geometry-such-as-hills/408907/3 "2026-09-11T17:31:41Z")

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hey, I don’t know if you are still here after 9 years but I am having the same issue on UE5.6.

Did you end up finding a solution?

Hope you are doing well.

Cheers

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**Author:** ![Husky211](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/husky211/32/1193324_2.png) [@Husky211](https://forums.unrealengine.com/u/Husky211)\
**Post date:** [September 11, 2026, 6:42pm UTC](https://forums.unrealengine.com/t/navmesh-cracks-in-irregular-geometry-such-as-hills/408907/4 "2026-09-11T18:42:54Z")

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> set each Cell Size as a multiple of each other and ensure the **Tile Size UU** is divisible by all the **Cell Sizes**

Gaps in the NavMesh are usually caused by incorrectly configured cell sizes

> **[Navigation Mesh Resolutions User Guide | Unreal Engine 5.8 Documentation |...](https://dev.epicgames.com/documentation/unreal-engine/navigation-mesh-resolutions-user-guide)**
>
> This guide will teach you how to use multiple resolutions within the same Navigation Mesh in Unreal Engine.

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**Author:** ![HelioHsx](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@HelioHsx](https://forums.unrealengine.com/u/HelioHsx)\
**Post date:** [September 12, 2026, 5:05pm UTC](https://forums.unrealengine.com/t/navmesh-cracks-in-irregular-geometry-such-as-hills/408907/5 "2026-09-12T17:05:39Z")

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My cell sizes are: low → 40, default → 20, high -\>10

Tile Size UU is 1600. I have “fixed tile pool size” unchecked.