Sight-Size

Sight-Size

Most drawing machines work from the outside in: take an image, find its edges, scribble along them, add some noise. The result always gives itself away in the same place — the marks do not know what they are describing. A stroke that crosses a bowl has no idea the bowl is round, so it cannot bend with it; a contour has no idea which side of the form is turning away from the light, so it cannot get heavier there. Everything is the same line everywhere.

So this sheet is built the other way round. There is a still life. It is actually there, in three dimensions, before anything is drawn.

Every vessel is one curve. A bottle, a bowl, a jar and a compote are all the same object here: a single polyline in radius and height that starts at the centre of the base, runs up the outside, turns across the rim, and comes back down the inside to the interior floor. Spin it. Because the traversal is continuous, the outward normal on the outside, the upward normal on the lip and the inward normal on the inside all fall out of one pass, which is why an open bowl gets a shaded interior without a line of code that knows what a bowl is. Fruit is the same curve with the return trip left off.

The ellipses are the camera’s, not a rule of thumb. A drawing student is taught that the further a circle sits from eye level the rounder it draws. That is a symptom, not a cause, and here it is never applied — a perspective camera is placed at a plausible eye height and the rims are simply seen. Where the outline of a horizontal circle sits is a two-line calculation: the tangent azimuths from the camera, the pair of angles where the line of sight grazes the circle. Rims below eye level close up, rims above it open the other way, and the foot of a tall bottle draws a rounder ellipse than its shoulder, because that is what happens and not because anyone said so.

One key light, plus the bounce. Every point gets a value from the light falling on it, and three things that are usually left out do most of the work: the core shadow, a band of the darkest tone lying just past the terminator rather than at the far edge; the reflected light thrown back up off the cloth, which is what keeps the shadow side from reading as a hole; and the occlusion that darkens the inside of a vessel with its depth below the rim. A bottle’s mouth ends up nearly black, a shallow bowl’s interior stays light, and neither was special-cased.

The forms, their cast shadows and the cloth are then rasterised into two off-screen maps at half size: one holds the value at every point of the sheet, the other holds what that point is part of and whether it is in light or in shadow. From there on, every mark is decided by asking those two maps a question.

The order of work

The sheet is not rendered and then made to look drawn. It is drawn, in the order drawings are actually made, and the order is most of the reason it reads as one.

The block-in comes first, in straight lines. The silhouette of each object is reduced to an envelope of five to eight straight sides, which is the Bargue exercise verbatim; the axis of each vessel is dropped through it, overshooting at both ends the way a searching line does; the construction ellipses are drawn whole, back halves included, because the back half is how you know the front one is right. Two plumbs and a level go in against the widest points. Afterwards it is rubbed back rather than erased, so the sheet keeps the ghost of its own measuring.

Then the contour, weighted. The outline is not one line. At every point along it the value just inside is sampled: where the form is turning into shadow the line is heavy, where the light is running along it the line thins, and where the tone inside and the tone outside are within about a tenth of each other the line is dropped altogether. That is what a lost edge is, and it is why the light side of a drawing can be almost empty and still hold.

Then light is separated from shadow, with one even layer of hatching at one angle across the shadow shape and nothing else — no modelling yet. Then the cast shadows. Only then does anything get modelled, and the strokes that do it run round the form: on a surface of revolution the line that follows the surface is the ring itself in perspective, so the modelling pass walks the rings and draws the visible part of each. Their pressure comes from the value, so they fade out in the light and stay quiet in the shadow, which is already flat.

The background arrives late and dies away toward the edges of the sheet, so the paper keeps its corners. The deepening crosshatch is six passes at six angles, each covering everything below its own threshold — so one layer lands in the halftone and six in the darkest dark. That is why the tone holds together: it was never painted on, it was accumulated, which is the only way hatching works. The accents go in last: every stretch of contour whose form is already near black redrawn heavier, and the line where each object meets the cloth, which is the darkest mark on any still life sheet.

The marks themselves

A stroke is a resampled polyline carrying a width and an opacity at every sample. Pressure sets both. Each one tapers in and out, bows very slightly, wanders on smooth noise sampled by distance travelled rather than a fresh random number per point, and breaks when the paper’s tooth takes a bite — but only at low pressure, which is where graphite actually skips. Hatch runs are cut at the length a hand can pull in one movement and restarted with a small gap.

Six media, and they differ in how they mark rather than in colour: graphite skips and varies in width; pen and ink has no pressure at all, so all of its tone must come from the crossing of the layers; silverpoint cannot make a dark, so the sheet stays in a narrow band near the paper; three chalks puts red on a toned ground with a black chalk reserved for the deepest passes and white for the highlights, which are drawn as cross-contours where the value runs above 0.83.

Control	Effect
Subject	What gets set up: a mixed still life, vessels only, fruit, or the four basic forms an atelier starts with
Medium	Graphite, sanguine, charcoal, pen and ink, silverpoint, three chalks. Each is a different relation between pressure, width, opacity and the paper’s tooth
Paper	Cartridge, laid with its chain lines, or a toned ground — on toned paper the highlights come back in white chalk
Carry it to	Which state to stop at. A block-in, an outline, the shadow shape laid in, modelled, or a finished study
Key light	Azimuth of the key light against the camera axis. Swing it round and the cast shadows, the counterchange behind the group and the weighting of every contour follow
Contrast	The ratio of key to ambient — a low setting is a north-window study, a high one is a raking light with a black shadow shape
Hatching	Spacing of every hatch pass at once, so the whole sheet coarsens or closes up together
Line weight	Base width of the mark
Pace	How long a sheet takes, from about half a minute down to nine seconds
Block-in, afterwards	Whether the construction is left in, rubbed back to a ghost, or erased
Set up another	Strike the group and arrange a new one
Finish this one	Skip to the end of the current sheet
Save sheet	The sheet as a PNG

Compositions are not accepted as they come. Eighteen arrangements are tried and scored against the things a drawing master would object to: forms that just touch instead of clearly overlapping or clearly separating, tops that line up in a row, one object swallowed whole by another, a group sitting dead centre. The best-scoring one is what gets drawn — which is also why occasionally you get a sheet that is merely competent rather than good. That is the honest part.