Visual occlusion and viz boxes

[jfa]

@anonymous_user_f2b8b290

If you are building a large environment you’re not going to want to use precomputed visibility. It doesn’t scale up well in either processing time or memory to large numbers of objects and view cells. It’s mostly for smaller levels and platforms that don’t have occlusion queries (mobile).

Sadly there are no UE4 docs on these systems, but the UE3 docs are mostly relevant:
http://udn.epicgames.com/Three/Preco…isibility.html

Dynamic occlusion culling is on automatically, it tests the bounding box of each object against the depth buffer from last frame to determine visibility. The default method right now is called HZB (Hierarchical Z Buffer) but there’s also the standard occlusion query method if HZB is disabled. You can test efficiency with ‘stat sceneocclusion’.

The main thing for building content is to make sure you have plenty of good occluders. This means zig-zags in the level, canyons, mountains, etc that block things behind them so they can be culled.

Is there anyway in UE4 to see stat of those?
I have used stat sceneRendering and saw initViews takes much longer with HZB than with standard hardware occlusion queries (HZB 0,91 ms and standard only 0,35 ms). I am still new to stat profiling and… well everything in UE4, but shouldnt HZB be more efficient than standard occlusion queries, or does it depend a lot on my GPU? I also notice FPS drop from 108,92 to 103,03 when using HZB.

Edit: Nevermind, seems like HZB should be really used only for large scenes with lots of occluders.