HDRP Avatars

Building Custom HD Avatars

These are mostly notes compiled during the development of the HDRP pipeline update. This guide isn't complete. It only discusses details about HDRP material setup, volumes, diffusion profiles, cameras and lighting. If you are not familiar with importing and building avatars for Mocap Fusion and the APS_SDK start by watching this tutorial.

If you are familiar with building mocap avatars for Fusion then rebuilding any avatar for HD should be a walk in the park!!

When rebuilding avatars for the HDRP pipeline the only difference is the materials!

Let's start by discussing using diffusion on materials, or sub surface scattering (SSS):

Diffusion Profile (Hair)

To add sub surface scattering (SSS) to materials for avatar hair, ears, fingers, you can create a modify any of the custom DP1..DP5 Diffusion Profiles to adjust color and scattering settings.

You must use one of the pre-defined profiles from the APS_SDK folder. You can modify them and the settings saved and bundled with the asset. Up to five custom profiles, so use them sparingly.

Create a material and assign one of the Diffusion Profiles to the material, if the material becomes pink/invalid click on the "Fix" button and it should render.

Up to five custom Diffusion Profiles (DP1..DP5) can be used for hair, ears, skin.. Maybe more in the future!

This animation shows a backlight that illuminates the hair and passes through the thin mesh giving a subsurface glow.

The light is a small area light + spot light rig.

The area light is used for accurate shadows up close, and the spot light so it glows in volumetric fog!

Diffusion Profile (Cotton Cloth)

For cotton or clothing you can use the built-in Cotton Thin diffusion profile, not all built-in profiles were included, but cotton is supported!!

Create a material and assign the Cotton Thin profile to the material, if the material becomes pink/invalid click on the Fix button and it should render.

Once the cotton-profile has been added you can use it on any clothing material in the scene.

For clothing use the built-in HDRP cotton shader. Works and is simple to create a new material.

No more flat shaded clothing, looks like real fabric.

You can also adjust the stitch pattern, the amount of fuzz...

Be sure to use built-in "Cotton Thin" diffusion profile.

Diffusion Profile (Ears + SSS)

More advanced masks can be used that allow you to control how light transmission affects the surface. Assign one of the unused custom Diffusion Profiles to the material

Create a material and assign one of the D1..D5 Diffusion Profiles to the material, make sure to use a unique profile.

If the material displays as pink click the Fix button.

The profile was added now adjust SSS and Transmission values.

Material Type

Set the material type to Subsurface Scattering.

Transmission Mask Texture

Materials with SSS enabled allow you to add a Transmission Mask, this tells the shader where to let light through and how much. It's the same as a UV texture but uses pixel intensity values as the weight. You can create a mask texture using Blender.

The transmission mask textures are simple and doesn't require much artistic ability, you can use Blender's Texture Paint tool and paint right on the model where you want the transmission to appear.

For ears typically the transmission is high in the middle and and less towards the edges, I added noise and dark spots so the light passes through the ear but is not perfectly. Also notice how the ears tips get full transmissive weight.

Also make the ears a separate material, in Blender assign just those faces you want SSS , this reduces the amount of work on the GPU.

Now assign the DP1 Diffusion Profile and set the color tint to (Hex: #4B282C) with a scattering multiplier of ~3 since ears are typically thin.

You should notice backlight passes through the ears where the transmission mask texture was painted.

Diffusion Profile (Wings + Translucency)

Enabling Sub Surface Scattering works to give the appearance of thin fabric or feathers. For wings setting the material type to Translucent allows light to pass through like paper.

For thin materials enable double-sided checkbox in the material inspector so light doesn't clip the mesh.

⚠️ Always enable depth-write in the material or it might not render properly against sky or backgrounds with fog.

If the material displays as pink click the Fix button.

The profile was added now adjust SSS and Transmission values.

Material Type

Set the material type to Subsurface Scattering:

Emissive lit material with area tube light for real-time light.

Translucent feathers thin fabric wings material with area and spot real-time lights in volumetric fog.

Avatars so real they get supermodel status.

Area Light Rig

When lights get close (less than 1 meter) to a surface it can cause issues with SSS and shadows, this applies only to lights that casts shadows.

Area lights produce more accurate shadows and give a better appearance on SSS materials but no fog.. Simple lights work with volumetric fog, but their near shadows are less accurate. So combine the two as a rig! Works for lights close to the avatar eg. desk lamp.

Next Page: HDRP Scenes

Pitfalls and Questions:

Why does my skin look plastic waxy in HDRP?

Subsurface Scattering too low try turning it up to (0.5 - 1.0). Use a diffusion profile with red tint. Test under rim light first ,

Translucency (SSS) on ears/nose - worth it?

Yes but keep it subtle. 0.1-0.3 strength, "thin" thickness mode, if it's too red, dial back albedo or use dark red tint in diffusion profile.

Fabric shader for clothes - does it matter?

Only if you're close-up. Use HDRP/Cotton shader. This adds stitching and fuzz detail at close-up.
If your avatar already includes clothing textures and normals you can use those too! Clothing shader optional

Main Page: HDRP Overview

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