Alpha Palette

From ZBrush Info

In ZBrush, grayscale images used for masking are referred to as alphas. You'll probably be used to alphas from the notion of an "alpha transparency" in other painting or imaging programs, but in ZBrush, they can be used for far more than that

1 Selecting Alphas
2 Alpha Palette Controls
3 Related Controls in Other Palettes
4 Further Links

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Selecting Alphas

Alphas can be selected from either the Alpha palette, or the large Alpha thumbnail on the left of the ZBrush canvas. In either case, click on the large thumbnail to bring up the full selection of alphas. Within the palette, you can also click one of the small thumbnails that show recently used alphas, to select it.

The inventory of alphas works the same as others in ZBrush, such as those in the Tool and Material palettes. The active alpha is grayed out to indicate that it is already selected.

Note: In the Alpha Palette, click one of the small thumbnails and then select an alpha from the resulting popup of the alpha inventory, to have the selected alpha replace the clicked thumbnail, rather than be added to the list of recently used alphas.

To see the name, size, and bit depth of an alpha, hover the mouse over its thumbnail.

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Alpha Palette Controls

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Main Controls

Import: Imports .bmp (Windows Bitmap), .psd (Photoshop), .jpg (JPEG), or PICT (Mac). You can select multiple alpha images and load them all at one time. If you import color images, they will automatically be converted to grayscale.

Export: Exports 8- bit .bmp (Windows Bitmap), .psd (Photoshop), or PICT (Mac).

Ep: If pressed, then any alpha that is exported will include the modifications made to it by the AlphaAdjust curve. (This is the same as the alpha that appears in the large thumbnail preview.) If not pressed, then any exported alpha will have its 'original' appearance, without modification by AlphaAdjust.

DE Options: Brings up options having to do with how the Alpha Displacement Exporter exports alphas. This includes options concerning TIFF file format, and some modification options.

DExporter: Exports an alpha using the currently selected options in DE Options. This differs from Export in that Export does not apply any of the options that can be set using DE Options.

Brush: Slider that gives an alternative way of selecting alphas.

R: As alphas are selected, they will be added to the "recently used" set of thumbnails that appears in the Alpha palette. In time, this may cause the palette to become too long for your preferences. Pressing R resets the recently used section of the palette to display its original number of thumbnails.

Blur: Blurs the alpha image to smooth it. Negative values will sharpen.

Noise: Adds noise to the alpha image.

Max: Maximizes tonal range of the current alpha. Like an auto-level setting, it adjusts the lightest part of the existing alpha to pure white and the darkest part to pure black.

MidValue: When applying a displacement map, tells ZBrush what alpha intensity to use as the neutral (no displacement) value. This is useful when applying displacement maps that weren't created in ZBrush and don't conform to ZBrush's standard of 50% gray meaning no displacement.

Rf: Radial Fade. Higher settings cause the alpha to fade out faster as it approaches the edge from center.

AlphaAdjust: Click to expand this control to an editable curve. Once open, you can add points and otherwise adjust the curve to cause different radial effects with the same alpha. For example, to the right are a simple alpha without AlphaAdjust modified, and the same alpha with a different AlphaAdjust curve. Note effect on selected alpha.

Flip H: (ZScript name is Flh) Flips the alpha left-to-right.

Flip V : (ZScript name is Flv) Flips the alpha top-to-bottom.

Rotate: (ZScript name is Rot) Rotates the alpha 90 degrees per click.

Invers: (ZScript name is Inv) Produces an inverse image of the alpha.

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Creating Polymeshes From Alphas

MRes: Sets the resolution of a mesh created using the Make 3D button. Higher values result in a greater level of detail at the price of a greater number of polygons and larger file size.

MDep: Sets the thickness of a mesh created using the Make 3D button.

MSm: Sets the smoothness of a mesh created using the Make 3D button. If this slider is set to 0, the mesh is created using Cubical Skinning, wherein the object appears to be composed of many tiny cubes.

DblS: When pressed (the default), a 3D object created using Make 3D wll be mirrored along its Z axis. For example when using a radially faded alpha such as Alpha:Brush 01, setting this to on will produce an object that looks like a sphere or ovoid; with it off, the result would be an object like a flattened hemisphere with a flat bottom.

Make 3D: Creates a 3D mesh skin from the currently selected alpha. The skin has symmetry along the Z axis, and is automatically assigned Adaptive UV Tiles coordinates.

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Converting Between Alphas and Other Objects (Stencils, Textures, the Document, Other Alphas)

Make Tx: Creates a texture from the currently selected alpha and adds it as the active texture to the texture palette.

Make St: Creates a stencil from the currently selected alpha and activates the stencil.

Make Modified Alpha: Creates a new alpha which is derived from the original alpha by "baking in" the modifications made by AlphaAdjust. In other words, if you start with an adjusted alpha and do a Make Modified Alpha, the new alpha will look the same when AlphaAdjust is in its unadjusted (original) state, as the old alpha did with the adjustment applied.

Cc: (Clear Color): This option works in conjunction with the CropAndFill button, and then only when the current alpha is the same size as the current drawing area. When it is on (the default), pressing CropAndFill will clear color information from the canvas, meaning that the resulting canvas will have depth but no color. If it is off, then the resulting canvas will have the same depth as when it is on, but pixols will assume any colors that were on the original canvas. If you CropAndFill a canvas with a differently sized alpha, then colors are always cleared.

CropAndFill: When pressed, resizes the drawing area to the size of the currently selected alpha, and then adjusts the depth of the pixols on the canvas according to the intensity of the alpha at the corresponding points. If the alpha is the same size as the canvas, you have the options of preserving canvas colors; see Cc above.

GrabDoc: Creates a new alpha the same size as the current canvas, with intensities determined by the depth of the pixols on the canvas.

Alpha Depth Factor: This affects the intensity with which the CropAndFill operation is applied, causing alpha intensities to map to greater or lesser depth displacements according to this scaling factor. It is also of significant importance when generating displacement and bump maps using ZBrush, when it gives a number that is used in an external renderer as a scaling factor. See the Displacement Exporter for further details.

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Related Controls in Other Palettes

Below are tools that appear in other palettes, but that relate to alphas in a significant way.

Draw:Current Tool Preview: With the SimpleBrush selected in the Tool palette,you can view and rotate this preview to get an idea of the depth effect of the alpha.

Tool:Masking: The Create Alpha and Alp buttons in this subpalette allow you to create an alpha from a mask on the current 3D object, or to apply an alpha as a mask.

MRGBZ Grabber: This tool in the Tool Palette allows you to (among other things) grab a portion of the canvas and turn it into an alpha.

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