Sculpt Tool properties

General

Size: Sets the radius of the tool. Size is measured in world space units (for example, a default Size of 100 = a radius of 100 centimeters). Hotkeys: press b and drag, or press the square bracket keys, [ to reduce size and ] to increase size.
Paint, lasso, and region modes: Apply only to the Freeze and Mask sculpting tools, the Weights posing tool, and the Faces and Objects selection tools. Lets you set how the tool is applied to the mesh. See also Mask or freeze regions on a model, Select and move items, Adjust a joint's region of influence.

Regular stroke: Lets you apply the tool with the default painting stroke.
Lasso: Lets you drag to create a free-form area where you want to apply the tool.
Region: Lets you drag to create rectangular region where you want to apply the tool.

Strength: Determines how much the tool affects the surface. Depending on the tool, this value represents either a percentage of the maximum power available or a height expressed in world space units. Hotkeys: M + drag, or press ; (to reduce strength) and ' (to increase strength).
Mirror: Reflects a stroke from one side of a model to the other, along the specified axis:

Off: Strokes are not reflected.
X: Reflects strokes across the world space X-axis.
Y: Reflects strokes across the world space Y-axis.
Z: Reflects strokes across the world space Z-axis.
Local X: Reflects strokes across the local space X-axis.
Local Y: Reflects strokes across the local space Y-axis.
Local Z: Reflects strokes across the local space Z-axis.
Tangent: Reflects strokes across the topological center line of a topologically symmetrical model. To use tangent space mirroring on a model, you must first define the model's topological center. See Set a topological axis.

Invert Function: Inverts the function of the tool. For example, if the primary function of the tool is to pull vertices up, its inverse is to push vertices down. Not all tools have an inverse function. Default hotkey: press Ctrl to invert function while sculpting.
Use Stamp Image: Turns on the selected stamp for the tool. Stamps modify the strength of the sculpt brush according to the gray scale values in the stamp image. The darker the overall values the lower the strength of the tool. Not all sculpt brushes work with stamps.

Orient To Stroke: When on, the stamp orientation follows the direction of your brush stroke.
Rotate: Rotates the stamp image clockwise.
Horizontal Flip: Flips the stamp image horizontally.
Vertical Flip: Flips the stamp image vertically.
Randomize: Turns the Randomize options for the tool stamp on or off.
Random Horizontal Offset: Randomizes the horizontal position of the brush tip dynamically through the stroke.
Random Vertical Offset: Randomizes the vertical position of the brush tip dynamically through the stroke.
Randomize Rotate: Randomizes the rotation of the brush tip dynamically through the stroke.
Randomize Scale: Randomizes the size of the brush tip dynamically through the stroke.
Randomize Strength: Randomizes the strength of the brush tip dynamically through the stroke.
Horizontal Flips: Randomly flips the position of the brush tip along its X axis dynamically through the stroke.
Vertical Flips: Randomly flips the position of the brush tip along its Y axis dynamically through the stroke.

Stamp Spacing: Controls the stamp frequency/continuity on a stroke. Depending on the Size and Falloff settings for a tool, the Stamp Spacing can be set to a higher value to refine the tool behavior and improve the appearance of the stroke. The default setting is 6.25 and ranges between 0 and 100. The higher the setting, the more gaps appear on the stroke, depending on the tool settings.
Steady Stroke: Helps to produce a smoother stroke by filtering mouse/stylus movement. When on, a vector displays on the tool cursor and no stroke appears until you drag a distance equal to the length of the vector. The length of the vector is set by the Steady Stroke Distance property.
Steady Stroke Distance: Sets the length of the Steady Stroke vector on the tool cursor.
Snap to Curve: When on, the tool snaps to an active curve when the cursor travels within the specified Distance. See also Sculpt or paint using curves.
Snap to Curve Distance: Sets the distance your cursor can be from a curve before snapping occurs. Default is 60.
Buildup: Specifies the rate at which the brush deformation grows to reach the Strength value (assuming a constant pen pressure).
Flood: Applies the tool uniformly across the entire surface. Does not apply to areas of the surface that are hidden, frozen or concealed by a stencil.
Reset: Resets the tool properties to default values.
Grab Silhouette: Specific to the Grab brush. When on, the tool grabs the front and back sides of the mesh silhouette together to modify it evenly. For better control, use an orthographic view (top, side) when applying this tool.
Follow Path: Specific to the Grab brush. Makes the mesh follow the path of your stroke as you pull extensions out with a sweeping gesture. Stroke more slowly to extend the mesh further. When off, the Grab brush pulls extensions out along a straight line.

Image courtesy of Andrei Cirdu

Falloff

Lets you specify how the tool effect diminishes (or not) from its center point to its outer edge. The falloff is represented as a curve that can be edited. See also Adjust tool falloff.

Falloff presets are available in the Falloff tray.

Snap: Constrains points to the grid.
Store To: Saves the current falloff curve to the tray.
Falloff image: Right-click the falloff image in the Properties window for the following options:

Insert Point: Inserts a new point under the cursor.
Select Point: Selects the point under the cursor.
Delete Point: Deletes the point under the cursor.

Falloff based on Facing Angle: When on, Mudbox reduces the effect of the Sculpt or Paint tool on parts of the model that face away from the camera. You can define the threshold values for the falloff using Falloff Start Angle and Falloff Range values.

For example, if the Falloff Start Angle is set to 85, and the Falloff Range is set to 5, faces with a facing angle from 0 to 85 degrees have no falloff. From 85 to 90 degrees, the falloff goes from nothing to full. For faces with facing angles over 90 degrees, the brush has no effect at all.

Falloff Start Angle: Sets the maximum angle below which no falloff is applied. The allowed range of values is 0 to 90.
Falloff Range: The number of degrees over which the falloff goes from minimum to maximum. The allowed range of values is between 0 and 180, minus the Falloff Start Angle value. For example, if you set the Falloff Start Angle to 45, the Falloff Range can be from 0 to 135.

Advanced

Remember Size: Preserves the size of the tool after use. When off, the brush inherits the size of the previously used brush.
Orient To Surface: Orients the tool cursor display (in the 3D View) along the normal of the face under the center of the cursor ring. Influences cursor display only, does not influence the effect of the brush on the surface.
Draw From Center: Specific to the Imprint tool. Sets how the stamp image expands outward from where you click-drag to apply it. When on (default), the center of the stamp is anchored where you click. When off, the edge of the stamp is anchored. Keeping this option on can be useful especially when using an extracted vector displacement map as your stamp.
Affects All Layers: Specific to the Smooth tool. When on, all sculpt layers are affected by the tool. When off, Smooth affects only the current sculpt layer.
Update Plane: Specific to the Flatten, Wax, Scrape, Fill, and Contrast tools. Recalculates the underlying tool plane (that affected vertices within the tool cursor move toward) for each stamp in a stroke. When off, the underlying plane is determined by the initial stamp and remains fixed for the duration of the stroke.
Whole Stroke: Specific to the Flatten, Wax, Scrape, Fill, and Contrast tools only when Update Plane is on. Continuously recalculates the underlying tool plane from all the vertices affected during the stroke.
Smooth Values: Specific to the Freeze, Mask, and Erase tools. Switches the current brush from applying freezing or masking (depending on which tool is selected) so the stroke blurs the color per vertex information on any existing freezing or masking. This only works if Smooth&Paint Values is off. Hotkey: Shift.
Smooth & Paint Values: Specific to the Freeze, Mask, and Erase sculpt tools. Applies freezing or masking (depending on which tool is selected) while blurring the color per vertex information.

Pen Pressure

Min Size: Specifies how small the tool is when the lightest pressure is applied to the pen, expressed as a percentage of the tool’s Size property. For example, a Min Size of 100 indicates there is no size variance, regardless of the pressure applied.
Min Strength: Specifies how weak the tool strength is when the lightest pressure is applied to the pen, expressed as a percentage of the primary tool Strength value. For example, a Min Strength of 100 indicates there is no strength variance, regardless of the pressure applied.
Direction: Specifies the direction vertices move when affected by a tool:

Center Normal: Moves vertices in the direction of the normal of the face directly under the center of the tool.
Averaged Normal: Moves vertices in the direction of the average of the normals of all affected faces.
Vertex Normal: Moves each vertex in the direction of its own normal.
Forward: Moves vertices in the direction of the stroke.
Right: Moves vertices perpendicular to the direction of the stroke.
X: Moves vertices along the world space X-axis.
Y: Moves vertices along the world space Y-axis.
Z: Moves vertices along the world space Z-axis.
Camera: Moves vertices toward the camera.
Screen: (This is the default setting for the Grab brush.) Moves vertices along the screen plane.