MetaHuman Stylized Character - Texture and Material Editing

Have you ever wanted to create a stylized character for your Unreal Engine or UEFN project? In this section of the MetaHuman Stylized Character tutorial, you will learn how to adjust the standard MetaHuman textures and materials to better suit your stylized character. 

In this part of the tutorial, you will:

• Establish a starting point with textures and materials assembled from MetaHuman Creator.

• Set up a look development (lookdev) environment where you can adjust texture and material settings.

• Learn core concepts behind using the realistic MetaHuman textures and transforming them into a stylized appearance, and some general tips for adjusting the skin, eye and hair materials.

Prerequisites

The MetaHuman Stylized Character tutorial shows how to convert your stylized character into a MetaHuman using MetaHuman Creator, and how to make the necessary changes to the rig and geometry to match your original design. You can follow the tutorial using your own character asset with the following guidelines:

• Your character has been imported into MetaHuman Creator and is currently assembled in the MetaHuman A-pose.

• You have exported the DCC folder package from MetaHuman Creator.

• You have Maya and the MetaHuman for Maya plugin installed.

• You have made updates to the facial and body rigs, and transferred those updates to your character in Unreal Engine.

This tutorial is designed to be completed in sequence. If you have not completed the previous step, see Body Rig Editing.

Check out the end result of this tutorial by downloading the MetaHuman Vampire Character Asset available on the Fab Marketplace.

For more information on the software and plugin requirements for this tutorial see the MetaHuman Stylized Character Tutorial landing page.

Texturing Setup

While you are aiming for a stylized look, you still want the character to follow standard Physically Based Rendering (PBR) material conventions. To help with this, you can use MetaHuman’s source textures as a starting point for the albedo, normal, and cavity maps.

Using MetaHuman’s texture synthesis model, you can select an appropriate starting point. For the vampire, you don’t want overly prominent features such as stubble, freckles or wrinkles. So you will want to prioritize finding a face texture that is relatively smooth but still has clear skin pigment variation to use as a guide.

With the desired face textures selected and high resolution texture sources downloaded, you have  three options for  look development:

• The first option is to use the Assembly tool and the baked materials plus textures as your starting point. This workflow is appropriate if the character model and rig are already locked and have been adjusted outside of MetaHuman Creator, which is the case for this Vampire character (rig and model changes were made in your external 3D applications and imported into Unreal Engine).

• The second option can be useful for your own characters if you are iterating directly in MetaHuman Creator with the sculpting, blending and mesh import tools and want to continue to iterate inside of MetaHuman Creator before assembling. It is possible to take advantage of the Override Materials and Custom Lighting Scenario features in Unreal 5.8 and above to iterate on the material and texture look development directly inside MetaHuman Creator. Under the Export tab, you can select Export Materials and Textures and apply them as overrides. For more information on these features, see the MetaHuman Creator Export Tool and MetaHuman Creator Material Overrides documentation. This process automatically exports and assigns the unbaked materials and textures to the MetaHuman Character. 

• A third option is to assemble the MetaHuman with unbaked materials and work directly on an assembled MetaHuman with unbaked materials and textures. This option offers the greatest level of flexibility, and provides for the most granular changes if you are still iterating in MetaHuman Creator. 

If you are using the vampire, you already have rigged skelmeshes and are aiming for a more simplified and stylized aesthetic, so a regular assembly with regular material and texture baking is sufficient to proceed.

By assembling the character with baked materials the final textures are:

• Base Color

• SRMF (packed Specular, Roughness, Metallic and Fuzz)

• Opacity (used for subsurface scattering modulation)

• Normal

These texture maps can be exported out of Unreal Engine and brought into your texture authoring software of choice. Substance painter was used for the vampire character.

Look Development (lookdev) Setup

With the textures authored to match the stylized character aesthetic, the next step is to add the material parameters that achieve the desired look. When adjusting material parameters, it is important to have a variety of controlled lighting environments to ensure the material responds appropriately to lighting. 

Since you have the skeletal meshes already imported from your external applications and have assembled the character Blueprint already, this part of the tutorial  on using Levels and Level Sequences for look development.

If you are using the vampire character, you will already have an assembled character Blueprint and can proceed by assigning the exported baked materials to the material slots in the Blueprint.

To set up your lighting, you will use two different lighting environments.

The first is the Texture Booth lighting environment that is part of the MetaHuman Creator Plugin that can be found in the Engine/Plugins/MetaHumanCharacter/LightingEnvironments/TextureBooth folder in the Content Browser. This lighting scenario uses large soft lights and is useful to ensure that the base color values for the character are correct.

The second lighting scenario is custom made. You will create a custom three-point lighting setup to ensure specular, normal, and subsurface responses are calibrated to the desired look.

This three-point lighting uses small rect lights to create regions of shadows and specular highlights so you can calibrate the material parameters appropriately. It is also useful to have the tonemapper disabled while calibrating material parameters.

To create the three-point lighting setup, follow the steps below:

• Create a new empty level and save it as L_LookDev. For more information on creating a new level, see Working With Levels.

• Drag your stylized character blueprint into the level.

• Open the Window menu then open the Levels panel.

• Click and drag the TextureBooth level from the Content Browser into the Levels panel to add TextureBooth as a sublevel. Save L_LookDev.

• Create a new empty level and name it L_ThreePointLighting. Save the new level and close it.

• Reopen L_LookDev and add L_ThreePointLighting as a new sublevel. Save L_LookDev.

• Right-click in the Content Browser and create a new Level Sequence in the Persistent Level.

• Add two new Level Visibility Tracks  by clicking the Add + button and selecting Level Visibility Track. For more information on working with Level Visibility Tracks, see the Level Visibility Track documentation.

• Create a new Cine Camera Actor in the Persistent Level. This will provide a consistent camera angle.

You now have a setup appropriate for material and texture-look development. The character Blueprint, Cine Camera Actor, and Level Sequencer with two lighting environments provides a consistent setup in which to iterate on the look of your character. 

Texturing Overview

You can now edit the MetaHuman baked texture to create a more stylized skin look.To give you more options, it’s useful to have a baked a set of maps using a high-resolution character model to help you with the texturing work — ambient occlusion (AO), cavity, and curvature maps can be used to dial in the look.

Start with the MetaHuman Skin texture as a base and remove as much of the realistic skin details and obvious noise as possible (moles, veins, and so on) to make the texture a bit more neutral, but using the overall pigment variation to guide the stylization process. This can take a few revisions to get something that feels right. Each iteration of the textures is checked in the lookdev setup and adjusted to get closer to what you are looking for. Using the Texture Booth environment with the tonemapper disabled is most helpful in this situation. In the case of the vampire, using the normal map and cavity as visual reference for placement, you can refine the lip contours and adjust the eyelid regions to match with the model. You can then change the face's general color to a purplish hue before accentuating some creases (such as the nasal labial fold and brow ridge) to a warmer, darker tone using an adjusted version of the baked cavity map.

You can also paint some hair to help blend the haircards with the skin. Here is our MetaHuman starting point, next to the finished texture:

Materials Overview

With the setup complete, it is time to start adjusting the materials. By directly plugging the maps into the head material, you already are getting a pretty good result. However, to achieve a more stylized appearance, there are a few adjustments that can help.

Skin Adjustments

The first step is to update the textures on your assembled MetaHuman and see where things are with the default settings:

You can achieve a more simplified skin response that doesn’t produce too much glossiness around the forehead, lips, ear regions by adjusting the global roughness value to a larger value:

While this helps, if you compare the before and after in the three-point lighting setup, the skin looks too matte now. Increasing the global specular amount to bring back some spec response while maintaining the desired roughness amount can help with that:

You can also adjust the subsurface scattering strength to create a more exaggerated skin-like material:

To exaggerate the look even further, there are a few more material parameters you could adjust. Turning off the tiling micronormals and enabling the fresnel fuzz can also help achieve a softer stylized appearance:

With these texture and material adjustments dialed in, you have taken the MetaHuman base textures and materials and achieved a stylized appearance while still benefiting from MetaHuman technology.

Eye Adjustments

With the skin in a good place, you can move onto stylizing the eye material. Start with the baked eye texture and use a texturing application such as Substance Painter or Photoshop to exaggerate the colors.

You can directly override the eye material’s input textures with your adjusted textures:

You will also want to make some changes to the material parameters to better fit this aesthetic. By tweaking the Cornea Size to around 0.155 and the Iris Scale to a value around 1.48 you can rebalance the eye material to better suit the exaggerated face proportions of this character. One last thing would be to change the sclera normal map to a flat texture to simplify the appearance even further.

Optional Hair Card Adjustment

You can fake some depth in the hair cards by creating a second UV set without any overlapping UVs and baking out an AO map.

End Result

By making these adjustments, You have successfully managed to transform the MetaHuman textures and materials to suit a more stylized aesthetic.

Next Steps

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  MetaHuman Stylized Character - Final Assembly

  How to finalize and assemble your stylized character in MetaHuman Creator.