How well does UE4's depth buffer work on very large scenes (>200 mi)?

I’m hoping to use UE4 as the base for a flight simulator. As such, I need a designed max view distance of about 300 km (~ 200 mi) to support high-altitude views. In most cases, this would exhaust even a 32-bit depth buffer, and special work would need to be done to support the dynamic range of the depth buffer due to seeing terrain anywhere from 1 km to 200 km distance.

How does UE4 handle this kind of situation? Would it be able to handle this kind of dynamic range in its depth buffer without issues, or would I have to worry about Z-fighting?

If UE4 can’t handle it out of the box, how hard would it be to modify the engine to support multiple view frustra to render distant and close terrain in separate batches?

Hello magicstix,

From my experience building in real world scale within UE4 can cause issues like Z-fighting. At a certain distance the depth buffer will start to have it’s limitations, as is true in all other software. This typically does not become an issue until you begin to zoom in extremely far, or you have a very empty scene and you are trying to see an object in the distance.

For outdoor scenes, this is typically broken up by foliage, depths of field, and other such workflows. To modify the engine, you would need an open source version of the engine from GitHub. From there you have the source code to begin and modify the engine. However, after doing this, we do not support the modifications or guarantee that your build will work. Typically changing a certain function within the editor changes the way the editor itself functions with other features.

I would not recommend doing this nor do I see this becoming supported in the future. This is a limitation of extreme values within UE4.