Hi! I have a question about HLOD (4.11).
According to Unreal Engine 4.8 Release Notes | Unreal Engine Documentation it should generate a low-detail mesh for a group, if Simplygon avaliable. If not, the LOD version of each mesh will be combined. If I understand correctly, if some meshes have LOD0 and LOD1, HLOD should use LOD1 for a group from that meshes. But in my case it uses LOD0. On large distances it reduces draw calls, but increases poly count. Did I missed something? Or it’s a bug? 
Additional question - UV of the HLOD groups. We’ve noticed, that UVs of the resulting mesh are not packed efficiently: they are just collected along side each other and then scale into UV space. This may be something that is still being worked upon, but maybe we are doing something wrong or missing something?
I was evaluating simplygon as well using the HLOD system… In short : not useful at all. I have a better suggestion for you. Instead of using HLOD use World Composition and put clutter into small levels. That helped me a lot on my scene. HLOD batches actors and replaces them with a single object, however, that object will increase your texture pool, because it creates that atlas…
I didnt like the system at all, the artifacts when combining actors was awfull… The Tris count you see is average. So instead of of having an average tris count of 10k you have a single object with a tris count of 230k… Now you could reduce the polycount with simplygon but the quality is just blah…
Thank you, Burnz! Not sure that World Composition will be enough for our project. It’s a big city, there are many complex modular buildings that visible at once, so I think we need some kind of tool to fight with draw calls.
Give it a try… we had the same issue, basically a huge town with lots of actors/buildings. You can make the levels as small as needed, e.g. we have a Dam with about 2000 actors inside a building. So the outside walls get loaded once the player is in the area, the interior gets loaded when the player gets very close to the building. Also, there is a “merge actors” function in the editor on experimental. If you use static lighting you can also use a precomputed visibility volume. But splitting up your city into sections should already help a lot.
You can also use simplygon to create LoDs and merge materials into atlases instead.
Your experience gives some hope. We’ll try of course. Thanks again.