Solver settings

Solution type

Line art or Luminance — which method makes the map. It sits above everything else because it decides which of the settings below exist at all.

Line art is the default and the reason this application exists. It reconstructs a surface from the silhouette and the hints you paint, so what it produces depends on the shape of the artwork rather than on how it happens to be shaded. Every other section on this page belongs to it.

Luminance is the standard method that most normal map generators use: brightness is read as height, and the surface is the slope of that height. It is here because a great deal of artwork is already shaded in a way that describes its form — hand-shaded pixel art often is, because the artist was thinking about light when they drew it — and on that artwork the result can be closer to what its author intended than a reconstruction would be. It is also instant, and it means you do not need a second tool to get one.

Its weakness is the one it cannot escape: it has no way to tell a dark pixel that is dark because the surface turns away from a dark pixel that is dark because someone painted it that way. Painted shadow becomes a dent and a highlight becomes a bump. If the artwork carries flat colour, hard-edged shading, or a pattern like scales or cloth, expect the pattern to come out as geometry.

Painted hints and every Drawn lines setting are ignored while Luminance is selected, and the panel says so. Nothing is lost — anything painted is kept and takes effect again the moment you switch back.

Bright pixels are

Raised or Recessed. Which way to read brightness. Artwork lit conventionally from the front means raised; artwork drawn as cavities, engraving or stamped detail means recessed.

This is the same setting as Curvature below, under a name that suits what it does here, so switching method does not lose it.

Depth

How far the surface is allowed to tilt, from flat at zero to a strong exaggeration at one. It scales the difference in brightness between neighbouring pixels, which is not a quantity in any real unit, so it is a dial to be turned by eye.

Smoothing

Blur passes over the brightness before the slope is measured. Pixel art usually needs at least one, which is the default: a single dithered pixel is a full-contrast step across one pixel, and the slope of that is a normal pointing almost sideways. Raise it for heavily dithered artwork, lower it to nothing for smooth digital painting where every detail should count.

The silhouette is handled for you. Most implementations of this method composite the artwork over white or black first, which puts a cliff around the outline and makes it the strongest feature in the result; here transparent pixels are simply not read, so the surface stops at the outline rather than falling off it.

Surface

Everything from here down belongs to the Line art method.

Curvature

Convex or Concave — which way the surface bends away at the outline. Convex is what you want for a character, a prop, or anything solid. Concave is for a hole, a socket, or an impression stamped into a surface.

Follow overall form

How strongly the interior is guided toward the shape of the subject as a whole, rather than being free to bulge on its own between folds.

This is the control for a pillowy result: a body divided by line work into separate patches, each rounding up independently, so the character looks quilted rather than solid. Turning it up makes those patches agree about the overall form and carry their detail on top of it. Turning it off lets each region round by itself, which can be what you want for something genuinely made of separate padded panels.

It costs extra solve time when on, since the overall shape has to be worked out before the detail can be laid over it.

Flatten interior

Pulls the whole interior toward facing the camera, uniformly. Off by default.

A blunt instrument, and mostly superseded by the Flatten tool, which does the same thing to a region you choose. If you paint a flatten region, this slider is suppressed and the panel says so — a global setting fighting a painted one is how a hint comes to look as though it did nothing.

Tube axis reach

How far the influence of a painted Tube axis stroke spreads outward, in pixels.

It needs to be at least roughly half the width of the limb, so that the influence reaches the outline on both sides. Too small and the hint has no effect; the application will tell you when the axis never reaches the outline. Only meaningful when an axis is painted, and the panel says as much when none is.

Drawn lines

The whole section has a checkbox. Switched off, line work is ignored entirely and the result is solved from the silhouette alone — occasionally useful on artwork with no line work, or to see how much of the result the lines are responsible for.

Fold angle

How sharply the surface turns at a detected line, in degrees. Higher is a more pronounced crease.

Stroke darkness

How much darker than its surroundings a mark must be before it counts as a line. Raise it if shading is being read as line work; lower it if genuine ink is being missed.

Max colourfulness

How much colour a mark may carry and still count as line work.

This is the control that makes the tool immune to shading, and it is worth understanding. Ink is usually near-neutral — black, or a dark version of the fill colour. Painted shading is usually a colour: a cool blue-grey shadow over green skin, say. Limiting how colourful a line may be separates the two. Raise it if your line work is drawn in a saturated colour; lower it if coloured shading is being picked up as lines.

Local contrast

How much darker than its immediate surround a mark must be. This is the threshold that distinguishes a line from a large dark area — a black cloak should not read as one enormous stroke.

Contrast radius

The one setting with a right answer rather than a taste, and the tool measures it for you when a sprite loads.

The surround a mark is compared against has to sit outside the mark. If the radius is narrower than your lines, a line is compared against itself and reads as a series of disconnected beads rather than a continuous stroke. If it is far wider, detection becomes insensitive.

The measured value is written into the control rather than applied invisibly, and named just above it — "hairline ink", "soft brushwork" and so on — so you can see it, question it, and override it. Artwork that mixes one-pixel ink with broad brushwork gets a measurement between the two, which serves neither; set it by hand to whichever matters more.

Sharp folds at strokes

Whether a detected line produces a crisp crease or a soft one. On for inked art, off for soft painted work where a hard crease at every stroke looks mechanical.

Detail methods

Alternative ways of guessing a surface, contributing an opinion that gets weighed against everything else rather than being blended over the result as an image.

• Follow drawn shading — reads the artwork's brightness as surface slope. The classic approach, available here as one voice among several.
• Add bevelled volume — builds volume up from the distance to the outline, giving a rounded-off edge.

Both start at zero, deliberately. Measured against the alternative, turning them on across a whole sprite tends to spoil the parts that were already right more than it rescues the parts that were not. They are worth having for surfaces nothing else describes — a texture with no clean line work, a form the silhouette says nothing about.

Give one a weight and it applies to the whole sprite unless you paint a region with Trust methods, in which case it is restricted to that region. The panel states which of the two is in force, because that is a fact about what the next solve will do rather than a description of a control.

Solver

Closed by default. Two controls, both of which have a sensible default you can leave alone.

Smoothness

How strongly neighbouring pixels are pulled toward agreeing with each other, against the outline's own conditions. Higher smooths detail away; lower follows it and can look noisy. Zero is a real setting here rather than off, which is why there is no switch beside it.

Outline blur

How much the estimate of which way the silhouette faces is smoothed. Low values follow stair-stepped pixel edges literally, which is sometimes exactly right for pixel art and sometimes reads as jagged. Also a real setting at zero.

Solve detail

Not settings — readings. The last solve's total time, a breakdown by stage, whether the displayed result is a draft or final, and a note when the solve fell back to the CPU explaining why. See Performance and hardware.

One setting the batch tool has and the inspector does not

--fold-weight sets how strongly the fold at a detected line is insisted upon, against everything else the tool is trying to satisfy. Lower lets the surrounding surface soften the crease.

It is not in the inspector because Fold angle covers the same ground more legibly for interactive work. It is carried in presets and honoured by the batch tool, so a value set on a command line survives being saved and reloaded. See Batch and the command line.