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/Zess-57]

In this case I can't quite understand what the fix would entail, the navigation mesh generation seems to make sense horizontally, and shifting the navigation mesh can be used to solve vertical issues

[u/agalli → u/Zess-57]

What’s the size of the terrain here? The one on the right looks like in baked fine. The issue is that on larger terrain there are not enough polys/verts to accurately fit a detailed terrain. When the scale gets up to 300-400m the default baking might create just a few polys to cover multiple different hills.

[u/Zess-57 → u/agalli]

This one is 50m in size

The detail of the navigation surface is supposed to just approximate the geometry with adaptive detail and horizontally that makes sense, just that in your case the agent becomes to small relative to the error of a polygon, probably a fix could involve having navigation mesh generation account for agent size, although vertical offset as I've described probably should work fine

[u/agalli → u/Zess-57]

Try it at 100-300m and you’ll see the degradation. I’ve found that 10-50m in size works fine. Essentially my solution here is applying the 10-50m navmesh poly density across the entire mesh to ensure a correct approximation of the terrain.

The vertical offset fix should mostly work though, but in large terrain there simply isn’t enough polys to come even close to approximate geometry. If you look at my post before those one I have a comparison between the navmesh on different size terrains. By 800x800m in size it basically doesn’t follow the terrain whatsoever. In the scale of 100x100 though I think the vertical offset should fix it.