How to Use Landscape Layer Blending and Height Blending

I recently delved into the basics of Unreal Engine 5 Landscape Materials and want to save you the trouble by summarizing what I've learned.

First, I want to outline my goals. I focused mainly on Automaterials, as it's fascinating how the texture changes depending on the terrain. This allows one to concentrate on sculpting while the material automatically enhances the result - one less worry.

Automaterials are fully parametric, automated landscape materials that make manually painting individual layers unnecessary. Simply assign the material to the landscape, and it looks good. A high-quality Automaterial is characterized by good optics from a great distance as well as up close. It integrates vegetation automatically and ensures high variation and minimized repetitions in the texture.

Although full automation is practical, I wanted to retain control over the appearance of my landscape. I intend to manually adjust certain areas, differentiate between biomes, and paint my own paths, forest floors, and grasslands. These biomes should use individual Automaterials that choose their textures based on slope and height in relation to the water level. Additionally, I want to manually add details like puddles and moss and ensure that vegetation appears depending on the painted biome. Forest floors should have leaves and branches, while meadows are covered with grass. However, I want the option to manually remove vegetation where it's undesired.

In this tutorial, I will present the basics that I painstakingly worked out to create such a material. However, I will distribute the topic over several articles, as it would otherwise be too extensive. If you're just getting into landscape design with Unreal Engine 5, this article can save you tedious research work.

The Basics of Landscape Layer Blending

So, let's start step by step. The first issue I noticed after looking at an Automaterial was the uncertainty about how to define your own layers that you can then apply to the landscape using the Landscape Paint Tool. The first step, therefore, is to clarify the question: "How do you paint a texture onto a landscape at all?"

First, you create a new Landscape and simultaneously a new Material. To create a Material that you can use for the landscape, simply right-click in the Content Browser and select 'Material' from the 'Create Basic Asset' list in the context menu. Name the material uniquely, such as "Landscape_Material". Then find the landscape in the Outliner and assign it the material as a parameter for the Landscape Material.

The defining texture on the landscape is controlled by feeding the Material Node with a texture. The simplest example we will create together is to set a single texture as Base Color. You can then simply assign the material to the landscape, and the texture will be displayed on it. For this, right-click in the Blueprint Grid and search for Texture Sample or Texture Object. Then connect this as Base Color. Subsequently, your entire terrain should be covered with the texture.

That's a good start, but we can further enhance the realism by fully utilizing the potential of the material functions. Quixel Bridge provides us with all the necessary textures to define the Base Color, Normal, Ambient Occlusion, Roughness, and Displacement of the material.

Get Your Free Landscape Textures from Quixel

When you're looking for textures for your landscape, you'll find a variety of highly detailed surfaces in Quixel Bridge. If you don't immediately see the Bridge tab, you can easily open it via Window -> Quixel Bridge in the menu bar.

Select a surface in Quixel Bridge that suits your taste, download it, and add it to your project by clicking the blue Add Symbol. For my project, I chose the surfaces Rocky_Ground_vjdqcba and Dry_Sand_xfgpebk because they are excellent for demonstrating the blending of textures.

You'll find the downloaded material in a new folder that Quixel automatically creates for you. For example, under Megascans -> Surfaces -> Dry_Sand_xfgpebk are three new textures and a Material Instance for the Dry Sand Surface. We can ignore the Material Instance for now, as we're creating our own material.

Quixel provides three textures for each surface: D, N, and ORDp. The D (Diffuse) texture is used for the Base Color, the N (Normal) texture for the Normals, and the RGB channels of the ORDp (Occlusion, Roughness, Displacement) for the remaining values. R stands for Ambient Occlusion, G for Roughness, and B for Displacement. If you integrate these textures into the Landscape_Material, you should immediately see an appealing texture on your landscape.

Scaling the Texture

The first thing you notice is the clear repetition of the texture. I swapped the texture for demonstration purposes, as with this one the repetitions are more obvious. According to Quixel, the texture should be 2x2 meters in size. However, a 2x2x2 meter cube created and placed in the world as a reference shows that this is not the case – the texture repeats much more frequently.

To fix this problem, I like to use the WorldAlignedTexture and WorldAlignedNormal Node. There, you can simply enter the value 200 as TextureSize (since the Unreal Engine calculates in cm), so that the rendered size exactly matches the intended size of the texture. Now it has the perfect size on the landscape.

Now, looking at the repetitions of the ground texture, the 2x2x2 meter box exactly matches the 2x2 meter repetition pattern of the texture. If the surface according to Quixel had a size of 3x3 meters, you would simply enter 300 for the TextureSize, and for 4x4 meters accordingly 400. This simplifies the process enormously, saves a lot of trial and error and calculating, and ensures that the texture always looks as intended by the creator.

Creating Landscape Layers

Currently, we have a texture on the landscape, but we can't paint different substrates on it. If you try to paint textures on the landscape, you'll notice that no layers are listed under Target Layers to select from. So how do you add multiple layers to the material for our layout? These layers are created in the material that we use for the Landscape Material, so we need to adjust this material.

Building the First Landscape Material

The heart of layer blending is the Landscape Layer Blend Node. Simply create it with a right-click and search entry in the Blueprint, clamp it to the Material Output, and it's ready for use.

To connect the Landscape Layer Blend Node to the Landscape Node, first activate the option Use Material Attributes. This allows the Landscape Layer Blend to be linked to the Material Output. Alternatively, the output of the Landscape Layer Blend can be inserted into a Break Material Attributes Node and then everything can be individually connected to the Material Output Node.

Now the individual layers need to be created that you want to paint onto the landscape. Click on the Node and look at the array of layers in the Details panel. There, you can add as many new layers as needed via the Plus Icon. For each layer created in the Node, input pins will then appear to which you can connect the material that should appear when the layer is painted with the Painting Tool.

We already have one layer. Now we need to connect everything. Since we have 5 outputs and one input for each layer, we first have to create a Material Attribute from the textures and link the textures with it before we can pass it to the Landscape Layer Blend as a parameter. This works with the Make Material Attributes Node.

We can repeat this process as often as we like. For demonstration purposes, I only created it for two layers, but you can create as many of your own layers as you want.

After I've now created two layers and connected one with Rocky Ground and the other with Dry Sand, the terrain initially appears black. This is normal, as two steps are still missing before we can see and paint something. However, the two layers are already listed when you switch to the Paint tab in Landscape Mode.

But even now, the two layers are listed on the left when you switch to the Paint tab in Landscape Mode.

Painting Layers on the Terrain

To paint the layers on the landscape, simply switch from Selection Mode to Landscape Mode (top left in the Editor) and click on the Paint tab. Here are the layers listed that you created. However, the first time, the Layer Info objects are missing. There is a dropdown menu for the Layer Info for each layer. If you added a new layer to the material, initially no Layer Info is selected there because it doesn't exist yet. Simply click on the Plus Icon to create a new Layer Info for each layer.

In Unreal Engine, a newly created layer in your material blueprint initially only defines the possibility of a texture – it's a template that says, 'Here could be a texture', but it lacks the specific instructions on how it should behave in the landscape. It's comparable to an empty area in a painting for which you haven't selected a color or texture yet.

This is where the Layer Info files come into play. They serve as detailed instructions for each layer. By creating a Layer Info, you practically generate an instance of this layer with certain properties and behaviors.

So far, I never had to edit the Layer Info directly; I just created it via the Plus Icon and then ignored it. Maybe it will become more relevant in the future, but I'm not aware of its further use currently.

Now you can apply your layers to the landscape. Select the desired layer, adjust the brush, and start painting.

Implementing Height Blending

Initially, I noticed the unattractive and unrealistic transition between textures. I experimented with various blend modes and first tested LB Weight Blend and LB Alpha Blend but was not convinced by either.

The Weight Blend worked, but I couldn't determine precisely, and the result was not satisfying. Alpha Blend also didn't achieve the desired effect. I wanted fine sand to first appear in the grooves between the stones before covering the higher areas, which meant considering the texture's displacement.

Fortunately, Unreal Engine 5 offers a ready-made solution for this. In the Landscape Layer Blend Node, you can set the Blend Type to LB Height Blend. This gives each Layer Input an additional input for the Height Mask.

For the Height Input Pin, I entered the displacement map of the texture, which provides exactly the information needed to achieve the desired effect. I was much more satisfied with the height information during the texture transition as it was taken into account.

Although the documentation on Landscape Material Layer Blending warns that problems may occur if all layers use Height Blending and recommends choosing LB Alpha Blending for the bottom layer, I never encountered the described errors where parts of the landscape were black. Therefore, I set all layers as LB Height Blend Layers.

However, the transition was still too subtle for my taste. So I implemented a CheapContrast to better control the intensity of the transition between layers. With a little experimentation with the settings, I achieved an aesthetically optimal result.

I've made the whole thing available in a small project for download if you don't want to implement it yourself or if you encounter obstacles. If you recreate the screenshot, you should achieve the same result. However, note that the rights to the textures are owned by Quixel, so I can't offer them for download.

The material can be applied directly to the landscape, but if you want to change parameters, you should first create a Material Instance and then apply it to the landscape. This will be explained further in the next article.