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Creating A Detailed Photorealistic Forest

Recently I’ve been researching UE4 forest creation for my game Lands Unknown (twitter.com/lands_unknown), and I’ve found several new techniques that I wanted to share. This is a simple step-by-step tutorial, although it is for more advanced UE4 users. We’re going to walk through the full process from tree modelling to lighting. Sorry for the rough layout, hope you find this helpful!

The result:

  1. The look
    We’re going to need to find the look and feel of our forest. For Lands Unknown I need thick, green mountain forests so I’m going to first search for references of these types of forests.
    I’m going to post some images from colourbox.com here so you can see what I’m aiming for.

https://forums.unrealengine.com/core/image/gif;base64
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2. Trees.
Obviously this is the toughest part, you’re going to have to get creative here because you’ll need massive, 100+ foot tall oak and elm trees and to this day there is nothing on the marketplace that both looks good and runs in an open world setting(if you’re interested in a custom photorealistic large tree pack, LET ME KNOW!!). The good news is that there’s a simple trick to making perfect trees if you’re willing to put some time into it.

Here’s what you do: Create a photorealistic high poly tree model using a tree generator(or find one online, blendswap and turbosquid are great sites, here’s a free one: https://www.turbosquid.com/3d-models…d-model/993087)

These high poly trees look incredible, but obviously at over 3 million tris on average you could never even get these into the engine, let alone run a world full of them. Our next goal is to get the trees down to 30k tris or less.

Next, find a good branch texture. Look on textures.com or just render out an alpha masked screenshot of one of the branches on the high poly tree.
Import the tree into your favorite modelling program(I use Blender) and replace each branch with a branch plane. For each branch you will need to duplicate the plane and rotate it in place several times to give it a 3-dimensional appearance. This is a slow, painstaking process, but necessary for a good result.

Delete the high poly leaves and use the Decimate modifier in Blender (or the equivalent if you are using a different program) to reduce the trunk polygons and move branches around until you reach around 30k tris.

Import the tree into UE4. When applying materials remember to set the SSS opacity as low as possible and tile a noisy normal map over the leaves to give them a bit more depth.

The result is a beautiful, low poly tree that will fit perfectly in our forest. This is what I got compared with Epic’s default Hilltree_Tall mesh.

Unfortunately Epic’s Kite Demo trees are so poorly optimized that our large, detailed trees have LESS THAN HALF OF THE TRIS of the small Hilltree_Tall mesh!

https://forums.unrealengine.com/core/image/gif;base64
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  1. The environment

The next step is to actually start the environment design. Create a new landscape layer for the forest floor. A dead leaves texture or a pine needles texture works best.

https://forums.unrealengine.com/core/image/gif;base64

Use the grass function to place clover meshes and other details on the forest floor. I use megascans assets for this.

https://forums.unrealengine.com/core/image/gif;base64

Use the foliage tool and paint some of your largest trees(usually oaks or elms) onto the terrain. Paint very sparsely at first, you are going to be adding other tree types later!

https://forums.unrealengine.com/core/image/gif;base64

Add some variety to the tree placement. Although the forest will be composed mainly of larger elm and oak trees, some areas can be covered with pines or birches.

  1. Ground Cover
    This next step can be very easy or very difficult, depending on what you’re trying to achieve. In this tutorial I’m aiming for a dense ground cover full of ferns, shrubs, and growing trees.
    Again, Blendswap and Turbosquid are great resources for smaller plants. It’s important to paint the plants by hand rather than using landscape grass because you need to have areas where only certain plants can grow. After the plants are placed, just scatter some photo scanned stumps and logs around for a little more realism.

  2. Lighting
    It’s so easy to mess up this last step that you’ll often find your forest looks worse than before. My best advice is to keep it simple, as long as you’ve got a low contrast lighting setup with an orange sunlight and blue skylight, you’re good.

Here’s some HD images of the result:



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