ZBrush — Likeness and Age Research

Research for the two ZBrush topics that were still open in ZBrush — Tutorials:

  1. sculpting a likeness from 19th-century photographs without a scan;
  2. age progression and regression, to sculpt the dated self.

It closes those research items and sets the rules the character artist and historian work to. Tutorials that apply it: Tutorial — Starting a Head and Base Body in ZBrush and Tutorial — Flat Albedo from Polypaint.

1. Reading early photographs as evidence

1.1 Mirror reversal

1.2 Colour sensitivity (daguerreotype and wet-plate collodion)

Early plates were sensitive almost only to blue, violet and ultraviolet light. As a result:

Real colour How it records Consequence for us
Warm, ruddy or tanned skin Darker than it was Don't read skin tone from the grey value. Use written descriptions and painted portraits
Fair skin Very light Can look paler than it was
Blue eyes Very pale, sometimes almost white Eye colour must come from written records, not the plate
Blond or red hair Dark or black Hair colour from written records
Freckles (yellowish) Much more visible than in life Don't over-paint freckles from photographs
Lips, rosy cheeks Dark or lost in shadow Lip colour is an interpretation; note it on the label

Hand-colouring was common: cheeks tinted pink, and gold on jewellery. Treat colour on a daguerreotype as the studio's addition, not evidence.

1.3 Exposure and pose

1.4 Lens and perspective

2. What is evidence and what is interpretation

Forensic facial reconstruction offers a useful model. Overall face shape and proportions can be reconstructed reliably. Lip thickness, mouth width, nose length, skin tone, eye and hair colour are uncertain without direct evidence.

Our figures have photographs, so we know more than a skull-based reconstruction would. The same honesty rule still applies:

Feature Evidence we rely on Label wording if not documented
Face shape, proportions, nose, brow, jaw Photographs checked for orientation, several angles if they exist —
Asymmetries, marks Only from orientation-verified images "Based on photographs"
Skin tone Written descriptions, painted portraits, historian's judgement "Skin tone is an interpretation"
Eye and hair colour Written descriptions (letters, passports, biographies) "Eye/hair colour from written description" or "interpreted"
Expressions beyond neutral Written descriptions only See Tutorial — Sculpting Expression Targets for the Expression Editor

Record every one of these decisions in the likeness log. The historian signs off on the log, not only on the final model.

3. Age: sculpting the dated self

3.1 What changes with age

Facial ageing works from the inside out:

  1. Bone. The eye sockets widen, the midface (maxilla) recedes, the pyriform aperture around the nose widens, and the jaw loses height and definition.
  2. Deep fat. It loses volume and sags, which hollows the midface, deepens the tear trough and flattens the cheekbones.
  3. Superficial fat. It moves downward. The upper and middle compartments thin and the lower ones thicken, giving jowls, deeper nasolabial folds and perioral folds. Compartments with looser connective tissue (nasolabial, infraorbital) sag first.
  4. Skin. It loses elasticity and gains fine wrinkles, uneven pigment and texture. This goes in the maps, not the mesh (Tutorial — Baking Detail Maps for MetaHuman).

Order of work in ZBrush: make each age change on its own layer (age_bone, age_deepfat, age_superficial) in the order above. Keep skin texture for the detail pass. This keeps age adjustable and makes it clear what was changed.

3.2 Regression (younger than the photographs)

This is the common case for us. Example: the 1847 comet night needs Maria Mitchell at 29, but the Maria Mitchell Association's portraits of her date from about 1851 to 1888. The earliest is about four years later, and most are much later.

  1. Start from the earliest reliable image. For a small gap (under 5 years), change very little: slightly fuller midface fat and less nasolabial depth.
  2. For a larger gap, work the layers backwards: restore deep fat volume first, then lift the superficial fat, then sharpen the jawline. Don't change the bone unless the gap covers middle age.
  3. Keep the landmarks (eye shape, nose, ear form) from the photographs. These change least with age and carry the likeness.
  4. Label it: "Appearance at 29 is reconstructed from portraits taken at 33 and later."

3.3 Progression (older than the photographs)

This is rarer. Work the layers forwards. The skin texture change is the most visible part at kiosk distance.

4. Getting the reference

5. Training (external)

Title Provider Type Link Use
Recreating a Historical Portrait in 3D The Gnomon Workshop Paid course https://www.thegnomonworkshop.com/workshops/recreating-a-historical-portrait-in-3d Closest match to our task; check content before buying
Creating Hyper Realistic Characters in ZBrush The Gnomon Workshop Paid course https://thegnomonworkshop.com/workshops/creating-hyper-realistic-characters-in-zbrush Realistic head anatomy and detail
Zbrush Character Likeness Sculpting Tutorial Udemy Paid course https://www.udemy.com/course/zbrush-2021-character-likeness-sculpting-tutorial/ Likeness from photographs (older ZBrush version; the method still applies)
Aging Characters in ZBrush Pluralsight Paid course https://www.pluralsight.com/courses/aging-characters-zbrush-143 Age progression
Creating an Aged Portrait in ZBrush Pluralsight Paid course https://www.pluralsight.com/courses/an-aged-portrait-zbrush-1134 Age progression
Oldify: character ageing kit 3D Scan Store Tool / reference https://www.3dscanstore.com/tools/oldify Wrinkle and skin reference (licence note above)

6. Decisions

Sources