Tutorial — Flat Albedo from Polypaint

How to turn ZBrush polypaint into a flat, unlit albedo (base colour) texture. We need albedo at two moments, and the rules differ:

Moment	Mesh	Purpose
A. Before Mesh to MetaHuman	The free-topology likeness sculpt	Helps the solver track features. Its UVs don't matter to MetaHuman
B. After calibration	The MetaHuman-topology head or body (the round-trip tool)	A Texture Override base-colour map in MetaHuman Creator. It must use MetaHuman UVs

Draft. Validate on the first texture pass and correct menu names here.

1. What "flat" means

Colour only: skin tone, freckles, moles, veins seen through the skin, lip and eyelid colour.
No lighting:
- no ambient occlusion;
- no cavity darkening;
- no specular highlights;
- no shadows baked in from photographs.
Even and symmetrical except for documented marks (a scar, a mole in a portrait). Record each one in the likeness log.
Skin tone comes from evidence: painted portraits, written descriptions and the historian's judgement. Early photographs record tone poorly, because of orthochromatic plates and toning.
- For figures of colour (for example Absalom Boston), take particular care and ask for review. Use a respectful, evidence-based range, and say on the label that tone is an interpretation.

Work at the highest subdivision level. Polypaint is stored per vertex, so detail needs density.
Turn Colorize on for the subtool. Fill a base skin tone (Color → FillObject) and build up regional colour:
- warmer on the cheeks, nose and ears;
- cooler around the eyes and the jaw shadow of shaved skin;
- lip colour.
Use the Standard brush with Rgb only (Zadd off), so painting doesn't sculpt.
Spotlight can project reference colour, but remove the lighting from the reference first: even the exposure, and paint out highlights and shadows.

If you painted on the free sculpt, move the paint across:

Load the round-trip tool (MetaHuman topology, MetaHuman UVs) and append the painted sculpt as a subtool.
Line them up. Both are in centimetres and in the same place if you followed the scale rules.
With the MetaHuman tool selected, and only it and the source visible, use Tool → SubTool → Project → ProjectAll with PA Blur at 0 and only colour projection turned on. Undo if the shape moves. Projecting shape would break the round trip.
Check that the shape didn't change: compare against the stored morph target.

Check the UVs: for moment B, keep the MetaHuman UVs exactly as they are. Don't run UV Master on them.
Set the texture size to match Creator (4K or 8K) in Tool → UV Map.
Tool → Texture Map → New From Polypaint.
Clone Txtr to send it to the Texture palette. Apply Flip V, which is usually needed for Unreal; check against a test image.
Export as 8-bit sRGB PNG or TIFF: T_<Figure>_Head_BaseColor_v###.png.
To export several subtools: use the Multi Map Exporter plug-in with Texture From Polypaint on, the same flip, and 8–16 pixels of padding.

Moment A: assign it to the sculpt's material before exporting to Mesh to MetaHuman (ZBrush — Sculpting for MetaHuman).
Moment B:
1. Import the texture into Unreal as a colour texture (sRGB on).
2. In MetaHuman Creator, open Skin → Texture Override and set Face → Base color, or Body → Base color.
3. MetaHuman 5.8 can also assemble with unbaked materials for finer look-dev control, and DCC Export now includes SMRF textures (specular, roughness, metallic, fuzz) for work in Maya.

Looks flat under even lighting: no baked shadows or highlights
The seams line up (neck to body; around the ears)
The tone has been reviewed by the historian and noted on the label if it is interpreted
File named, versioned and in source control