Creating an outdoor environment is both easy and hard. Getting the basics down pat is easy but if you want to make the best possible scene you're going to need to want to learn to use some of the systems built to handle them within @UnrealEngine. Time for a tweetorial! #UETips
Creating an outdoor environment doesn't start with the world, it starts with the project settings. Head to Project Settings->Rendering. Static lighting? Kill it. Having it enabled while using dynamic lighting adds overhead and you won't want lightmaps for a world that big. 
We're going to have a whole lot of foliage and that would normally mean overdraw but we can enable an Early Z Pass. It works by caching the pixel distance in a pre-pass to skip occluded primitives. Setting "Mask Material only in early Z Pass" *really* helps with dense foliage.
The other thing to do here is to take a look at shader permutations. Under the hood @UnrealEngine creates a bunch of permutations for different use cases to each material. If you know you're not going to need them then nuke 'em to save on shader compilation time.
Next up are distance fields. DFs are points in space that store their distance to the nearest surface enabling Distance Field AO. Check out this before/after to see why we want it. Enable "Generate Distance Fields" & "Generate Landscape Real-time GI Data".
docs.unrealengine.com/en-US/Engine/R…
docs.unrealengine.com/en-US/Engine/R…
Where do we start when it comes to making this thing? Well, my Bob-Ross-in-the-making: Landscapes. Landscapes are a system inside of Unreal that allows for scuplting & painting and sculpting but also automatically reduces polys to the level of detail and form required. Rad right?
Landscapes are pretty straightforward: You sculpt and paint surface materials. Be aware that the density and number of components that you set will affect the overall overhead and number of drawcalls associated with the environment. Handy chart here! docs.unrealengine.com/en-US/Engine/L…
I suggest enabling the new Landscape Layer System (with "Enable Edit Layers") for much easier editing. It lets you create additional layers and non destructively paint the environment in. That said, once you're up and running you should be sculpting and eroding in no time.
Whenever I start a new environment I throw in a directional light (with Sun Fog enabled), a sky atmosphere, a skylight set to Movable (needs to be set to enable Distance Field AO) and a height fog as a base setup to get a better read on depth and set things up for later.
If you haven't already you should get onto Quixel. It's free for all Unreal developers and it has an incredible number of textures and photogrammetry models. Another cool aspect is that it's pretty quick to stylize them through Quixel Mixer too! quixel.com
When it comes to Landscape Materials remember that you can use the Set Material Attributes to create materials that you can then blend together with the Material Attribute Blend. This helps keep everything contained in a single thread and more easily managed.
Unreal automatically places grass wherever you've painted it into your landscape. It's really useful and means the painting automatically adjusts the foliage above it. You can even set up your own rule sets in the material to place things with your own rules.
Landscapes support Blueprint Brushes. There are a few that you can enable using the Landmass plugin that's built in. The "Material Only" brush lets you easily add random noise while the Landmass brush lets you sculpt out areas using splines in a non destructive way!
Directional Lights can have Ray Traced Distance Field shadows nice cheap shadows. Applied to foliage it means we can get these much nicer shadows but remember to make sure it's enabled in the foliage settings for larger foliage because it defaults to off!
Outside the standard foliage system there's a Procedural Foliage system inside the Experimental Editor Settings. Devs set growth rules and how different foliage responds to shade and then it auto generates a forest. You can then modify it afterwards with the foliage tools!
The final feature that I'd like to touch on are Runtime Virtual Textures which let you reduce overall instructions and also sample the underlying landscape texture on foliage assets! I already did a thread on those that you can check out here.
Ok. That'll do it for today! Hopefully that helps some folks out! I'll try and get this and some more into a proper doc to help folks moving forward. Let me know if this helps and other areas you're curious about!
