The Asaro head

Origin and history

The planar head as an idea is much older than John Asaro. Albrecht Dürer's Vier Bücher von menschlicher Proportion, published posthumously in 1528, contains plane-diagrams of the head executed in the same spirit — a simplification down to flat surfaces designed for teaching.¹ The nineteenth-century Bargue lithograph series included planar studies of the head as one of its drawing exercises.² Andrew Loomis's Drawing the Head and Hands (1956) includes plane diagrams as an intermediate step between the ball-and-plane volume and the finished portrait.³ What John Asaro did, beginning in the early 1980s, was crystallise the twentieth-century version — a single canonical geometry, cast in resin, that everybody could refer to.

Asaro was teaching at Art Center College of Design in Pasadena, then as now one of the most influential American design schools. The institution's product-design programme demanded that students develop a fast vocabulary for rendering human heads under varying light. The existing references — Loomis books, Bargue plates, anatomical écorchés — were either too detailed to be teachable in a semester or too literary to be useful at a desk. Asaro's solution was to sculpt a physical reference object that any student could put on their workspace, light from any angle, and study directly.⁴

The original cast was developed iteratively over several years. Asaro began with a Loomis-style volume and progressively cut planes into it until the value transitions matched what he saw on actual heads under controlled light. The plane count settled at forty-one — though counts vary slightly between editions and printings of the cast — and the canonical geometry was finalised around 1985. From there the cast was produced commercially through Asaro Studios and distributed to art schools and ateliers throughout the United States.⁵

Why it caught on

Three factors combined to make the Asaro head the dominant lighting reference within roughly a decade of its release. First, the timing — the 1990s saw a resurgence of atelier-style classical training in America, and the Asaro head was a ready-made cast-drawing exercise that did not require importing nineteenth-century plaster casts at significant expense.⁶ Second, the geometry was teachable in a single semester, unlike the open-ended study of master copies. And third, by the early 2000s, the 3D-modelling software industry had adopted the Asaro mesh as a standard face-rig for character art training. Pixar, ILM, and the major game studios trained their face artists against the Asaro reference. The cast that began as an atelier teaching aid had become an industry standard.⁷

By 2020 a female-proportioned Asaro head was also commercially available, and several digital variants — younger, older, with stronger ethnic-specific proportions — were circulating in 3D-art communities. The model's underlying logic is geometric, not biological, so it adapts to those variations more readily than a strictly anatomical reference would.

The forty-one planes

The Asaro head's planes can be sorted into four regional groups: the cranium (top and back of head, eight planes), the forehead-and-brow band (six planes), the cheek-and-jaw mass (twelve planes), and the central feature mass — nose, mouth, chin (fifteen planes). Different editions of the cast move the boundaries slightly, but those four regions are stable across all versions.

The plane edges are the value transitions

The single most useful insight in Asaro pedagogy is this: every plane edge is a value transition. When light strikes the planar head, each plane catches the light at a different angle from its neighbour, and the boundary between them is where the value changes most rapidly — it is where the form shadow turns. A painter who knows where the planes meet knows where to put the sharpest value contrasts. A painter who does not is reduced to copying from photo reference and hoping the contrasts read.

This is why Asaro work transforms painters who were already technically competent. The geometry does not teach you to draw — Loomis and Bridgman do that — and it does not teach you likeness. It teaches you where the edges of your value structure must live. Once internalised, this knowledge survives even in difficult lighting where the photo reference is ambiguous.

The "key" landmark planes

Of the forty-one planes, six are considered key landmarks because they carry disproportionate visual weight: the forehead plane (top of the brow), the temple plane (side of the forehead), the cheek plane (top of the zygomatic), the jaw plane (side of the lower face), the nose-side planes (the left and right of the nose's bridge), and the chin plane (front of the jaw mass).⁸ If those six are correct in your study, the remaining thirty-five fall into place. Most introductory Asaro exercises focus specifically on those six.

Lighting the cast — single-source studies

Almost every Asaro learning sequence begins with single-source overhead lighting at the so-called Rembrandt angle — a 45-degree key light positioned slightly above the model's eyeline, throwing a triangular highlight on the shadow-side cheek. This pattern is canonical because it reveals every major plane of the head in a single setup, and because it matches the lighting most portrait painters end up working in for studio commissions.

The student's job at this stage is to identify, for each visible plane on the cast, which value family it belongs to: highlight, halftone, core shadow, reflected light, or cast shadow. Asaro's planar simplification makes this dramatically easier than working from a live model — the planes are unambiguous; you can see exactly where each value family begins and ends. After a few weeks of single-source studies, painters report that they can predict the value structure on a live sitter's head before picking up the brush.⁹

From single-source overhead, the standard progression moves through 90-degree side light (where half the head falls into shadow and only one cheek catches the key), then to under-light (a flashlight from below, which inverts the normal shadow pattern and is used in horror illustration), then to rim light (a key source behind the head, leaving the face in shadow with bright edges where the planes meet the rim). Each setup teaches a different subset of the planar geometry.

Two-source and ambient setups

After single-source mastery, the next stage is two-source lighting — typically a key source and a fill source at different colour temperatures. This is the lighting that most commercial portrait commissions are painted under, and it is where the Asaro reference proves itself most useful. Two-source lighting produces overlapping value families on every plane, and predicting their interaction by eye is essentially impossible without prior planar study.¹⁰

The classical setup is a warm key from upper-left and a cool fill from upper-right at roughly 1/3 the key's intensity. The Asaro cast under this lighting shows planes that fall into one of five categories: warm key only, warm key with cool fill, cool fill only, core shadow (neither source reaches the plane), and reflected light (planes that bounce light from nearby surfaces back into shadow areas). Studying which planes fall into which category is the entire intermediate Asaro curriculum.

Ambient and outdoor studies

The hardest light to paint is ambient — overcast sky, diffuse north-window, a studio with bounce cards rather than direct sources. Under ambient light, value transitions are soft, plane edges become subtle, and the painter must rely entirely on prior knowledge of the planar structure to find the value breaks. Most painters spend the final stage of Asaro study working specifically under ambient conditions, because if you can find the planes under diffuse light you can find them under anything.

Asaro plus Loomis — the canonical pairing

The Asaro head answers only one question — where do the value transitions sit — and assumes that other questions have already been answered elsewhere. Specifically, it assumes that you have constructed the head's volume correctly before you start lighting it. The canonical complement to Asaro is the Loomis ball-and-plane head, which builds the volume that Asaro then illuminates.¹¹

A typical advanced atelier workflow runs in two passes. First pass: Loomis construction of the head as a sphere with sliced planes, establishing the volume and the major rotation in space. Second pass: Asaro plane overlay on top of the Loomis structure, marking the value transitions and the lighting pattern. The two passes together give the painter a fully predicted value structure before any pigment touches canvas.

Reilly's rhythm chains pair with Asaro in a third way. Reilly carries the head's gestural flow; Loomis carries the volume; Asaro carries the lighting. Painters trained in all three describe their preparatory process as "Reilly for the curves, Loomis for the form, Asaro for the value." Each method answers a question the others ignore.

The Asaro head in 3D software

By the late 1990s, 3D-sculpting software had matured to the point where digital reproductions of the Asaro head were widely shared in art communities. The Pixologic ZBrush team produced one of the early canonical digital Asaro meshes around 2001, and it became part of ZBrush's default character library.¹² Blender, modo, and the major commercial 3D packages followed within a few years. Today every face-rigger entering the game and film industry has seen the Asaro head as part of their software's onboarding.

The digital adoption has interesting feedback effects on traditional teaching. Students who have already studied the digital Asaro mesh through ZBrush often arrive at the physical cast with a strong prior intuition for where the planes sit. The reverse is also true — painters who first learned from the physical cast can move into 3D character sculpting with significantly less onboarding than those who skipped Asaro entirely.

For digital portrait painters, the most useful workflow is to model the Asaro mesh in any 3D software, light it with the lighting setup the painting will use, and then render the cast as a value-only reference. This gives the painter a planar prediction of the value structure that updates with any change to the lighting — a workflow Asaro himself could not have anticipated when he sculpted the original cast.

Asaro vs Loomis vs Reilly vs Bridgman

The four methods do not compete; they answer different questions. A complete portrait education uses all four. The order of teaching that has emerged in American ateliers is Bridgman first (anatomy), then Loomis (volume), then Asaro (lighting), then Reilly (rhythm) — but the order is not rigid and some ateliers swap Reilly and Asaro depending on whether the student's first portrait commissions are studio or location-based.

Practitioners who built and continued the method