Identifying LOD candidates?

Hi,

Have been filling a level with a lot of foliage (not procedural, but using foliage painter, so only a very few actual placed trees) and over time the frame rate has slowed time, especially now I am working on lighting the area. I’ve kept an eye on it, but I need to deal with it. I’m just not sure how to go about identifying how to troubleshoot this?

  • Is there any way or quick tip on finding which assets are likely to benefit most from a few LOD levels?
  • does performance get nailed most by too many materials, and will consolidation improve performance, or will this just reduce memory usage?
  • i have a day/night cycle, so pretty much everything is dynamic. Should I completely remove static lighting?

Any other tips would be helpful, i did try the PIE Profiler, but it didn’t really help me much - specifically on helping me find slow meshes that need more LODs, or perhaps I dont know how to use it properly.

Appreciate any help.

Thanks
Stuart

  1. dont know if there are any guidelines for that, but always try to reduce as many tris as possible. e.g a tree with 7k tris can be reduced to 3k tris for the 2nd lod level but a grass mesh with just 6 tris wont benefit from another lod channel, as the look of it wont be so good anymore. In your LOD channels you can also reduce your materials -> e.g the last lod channel of a tree could be just a plane with one single material
  2. the performance depends on nearly everything -> tri count, material complexity, materials used on the mesh, lights,… Make sure that you dont use too many materials for one mesh, because otherwise you will have too many drawcalls. Btw, take a look at this thread: https://docs.unrealengine/latest/INT/Engine/Performance/Guidelines/index.html :slight_smile:
  3. for large levels with many meshes it’s better when you use dynamic lights so that you dont have to build your lights -> so I personally would set all to dynamic (of course it depends on your map)

Thanks…

For the benefit of others I have found this some useful info in this clip from Epic, which ror some reason, I hadn’t found before:

How to scale down and not get caught - The Unreal Engine 4 “Rivalry” Demohttps://youtube/watch?v=HY62PAsM7eg
And the biggest tip (for me) was to examine the results of “ProfileGPU”. I discovered my Moon was taking an awful amount of resource during the day!.. so something to turn off completely

Preformance gets nailed to vectors and polys