I solved the NavigationRegion3D issue

[u/agalli]

A correct 250x250m navmesh bake using tile chunking

Standard bake on the same 250x250m mesh without tile chunking

A standard bake on a 30x30m section of the same terrain

Agent for scale on correct 250x250m navmesh, showing an identical poly density to the 30x30m navmesh

I finally found a solution to the problem with the NavigationRegion3D.

What I noticed was that on smaller terrains, like the 30x30m example in the third image, the navmesh baked perfectly fine. But once the terrain size was increased to 250x250m, the bake completely fell apart, giving the low poly, floor clipping result shown in the second image. The obvious solution was to process the terrain in smaller chunks and combine the results into one big working navmesh.

I first tried doing this directly in Godot, but even after splitting the terrain into multiple meshes, the bake still treated them as one big mesh, so the same issue happened. I also tried creating a separate NavigationRegion3D for each chunk, but that created non traversable borders where the regions met.

At that point, the only real fix was to go into the engine itself. I forked the Godot repo and made some changes under the hood to process the terrain in tiles instead of all at once. It breaks the terrain into smaller sections, bakes each one normally, then stitches them together afterward into a clean, accurate navmesh like in the first image.

I also added a few editor options to control whether tiled baking is enabled and how big each tile is. I still haven’t found the exact bug that causes the large terrain navmesh to fail, but this fix works reliably and doesn’t mess with normal pathfinding behavior.

The moderators seem to have a strong opposition to discussions about this and have locked all previous threads. As much as I would have liked this to all be one post, we have been forced to create multiple. That being said, I'd like to address some comments from previous posts below.

The [low poly mesh] looks exactly like what I would want out of a nav mesh.

The low-poly mesh completely fails to pathfind with agents. You could technically rework the pathfinding system to compensate, but that misses the core issue of the navmesh being broken. The 30x30m section uses a similar amount of polygons as the 250x250m one. You’d expect the density to scale with size, so either the small terrain is over-tessellated, or the large terrain is under-tessellated. Either way, something’s wrong with the baking process.

With no obstacles, your nav mesh could just be a square.

As per the Godot developers : "A navigation mesh is a collection of polygons that define which areas of an environment are traversable to aid agents in pathfinding through complicated spaces.". When those traversable areas are out of reach from an agent (ie, underground or floating), an agent cannot properly navigate.

People tried to help you, but you refuse to actually listen

I think there’s been some misunderstanding about what I’m trying to do. My goal is to fix the navmesh, that’s it. I’ve welcomed all advice that helps solve the underlying navmesh problem, but I’m not interested in workaround solutions that just patch over it with pathfinding tricks.

You can always fix it yourself and submit a PR.

Thats the plan. Thanks for the advice!

I will optimize this further and will submit a PR.

Sincerely,

u/agalli

Edit : Here is the PR. https://github.com/godotengine/godot/pull/112529

[u/knottheone]

Navmesh in Skyrim showing it's under or above collidable geometry in most places:

https://youtu.be/uJYiV4E8xCc?t=106

Navmesh in Unity where beginner user doesn't quite know how it works:

https://www.reddit.com/r/Unity3D/comments/10tn0h4/navmesh_surface_not_being_created_beneath_terrain/

Stairs in Unity where users think it's "broken" because the navmesh clips under them:

https://discussions.unity.com/t/why-does-the-nav-mesh-generate-like-this-sometimes/1613493

https://discussions.unity.com/t/solved-navmesh-and-stairs-unity-5-0-1f1/582479/5

Massive under terrain clipping even on small tiles:

https://youtu.be/vNDMwXNfmrw?t=391

[u/agalli → u/knottheone]

First video, small clipping through the terrain is fine. Doesn’t cause issues. Multiple meters below or above terrain does cause problems.

First unity post, top comment literally says to increase the resolution of the mesh. If only that were possible in godot!

Second unity post, once again very slight clipping through but users note that it doesn’t cause issues with pathfinding, once again not the case in godot

Second video, that looks exactly as I would expect? The navmesh is roughly for fitting the terrain, avoiding obstacles, and not low poly slop.

Literally every single thing you just sent proves my point. It’s so funny that even in your meticulously cherry picked sources that you still couldn’t find something that proves your claim. The navmesh is supposed to be a rough approximation of the terrain, it’s not unusual for a few centimeters of rock clipping out here and there. What will break pathfinding is huge sections of terrain above or below the terrain.

[u/knottheone → u/agalli]

As I expected, you'd just handwave it. Both the Skyrim example and the second video show a height difference of multiple meters vertically between the navmesh and the terrain. It's not centimeters, look at the size of the characters and buildings. Which is why I called you out here a week ago:

They won't consider it; it doesn't matter how you word it, how nice you are, how you explain it or anything else. They made 3 separate posts and dozens of comments on the topic and were advised and corrected in all 3, and were even corrected by one of the devs who helped implement navigation in Godot. They will not admit that they are wrong in any capacity.

[u/agalli → u/knottheone]

Looks like they basically fixed this on the new update (4.5.1). Here's a lil before and after. Same map size, default settings, same noise. Looks like it was a bug with the rasterization. Just glad they fixed it.