Creating and exporting Alphas…(Mini-tutorial)

Hi :slight_smile:
When exporting a ZBrush image to be used in other programs, you may need to have an alpha (mask) created. This mini-tutorial describes four common methods that can be used when creating such alphas.

The following is a sample image that was created in ZBrush. The image is composed of 3 rings and a sphere. Each of these items was drawn with a different color and material.

The grayscale images are various alphas that can be created from the above sample image.

Instruction for creating the alphas…

Alpha 1: Creating a grayscale mask from depth(z) values…
This is the most common method as it allows depth information to be converted to alpha. This gray scale alpha represents the relative depth of each Pixol in the canvas. White=nearest, Black=farthest. This alpha can be used when applying ‘special’ depth-sensitive effects (such as fog and depth-blurring).

Instructions:
A. Select the MRGBZTool, Unpress TOOL :small_orange_diamond:MODIFIERS :small_orange_diamond:AUTO CROP.
B. Click in canvas and ‘drag’ to ‘grab’ the canvas. A new Alpha will be added to the ALPHA Palette and a texture will be added to the TEXTURE palette.
C. Export the new alpha from the ALPHA palette.
D. Switch to the target application and import the Alpha.

Alpha 2: Creating a simple B&W mask from Depth values…
Same as above with the added step to convert the grayscale into a B&W mask.

Instructions:
A. Select the MRGBZTool, Unpress TOOL :small_orange_diamond:MODIFIERS :small_orange_diamond:AUTO CROP.
B. Click in canvas and ‘drag’ to ‘grab’ the canvas. A new Alpha will be added to the ALPHA Palette and a texture will be added to the TEXTURE palette.
C. Export the new alpha from the ALPHA palette.
D. Switch to the target application and import the Alpha.
E. In the target application… Select all ‘black’ pixels of the alpha, inverse selection and fill selection with white.

Note: When an image has a simple flat-color background (such as the above image), you may choose to create the B&W mask from the texture in the target application by selecting all ‘background’ pixels and inversing the selection.

Alpha 3: Creating a multi-levels mask from color intensities…
This method is most effective when objects have been drawn with different colors (such as the above rings). This alpha allows you to select different parts/objects of the image based on color intensities.

Instructions:
A. Select the MRGBZTool, Unpress TOOL :small_orange_diamond:MODIFIERS :small_orange_diamond:SHADED MODE , Unpress TOOL :small_orange_diamond:MODIFIERS :small_orange_diamond:AUTO CROP.
B. Click in canvas and ‘drag’ to ‘grab’ the canvas. A new Alpha will be added to the ALPHA Palette and a texture will be added to the TEXTURE palette. You may now export the flat-shaded image and use it to create color-based selection in the target application or continue with the next step and export a grayscale version of the image.
C. Convert the new texture to an alpha by pressing the TEXTURE :small_orange_diamond:MAKE ALPHA button. Export this alpha from the ALPHA palette.
D. Switch to the target application and import the Alpha.

Alpha 4: Creating a multi-levels mask from material indexes…
This method is most effective when the objects have been drawn with different materials. This material-index channel allows you to create masks based on the material index of each object.

Instructions:
A. Select the MRGBZTool, Unpress TOOL :small_orange_diamond:MODIFIERS :small_orange_diamond:AUTO CROP, Press DRAW :small_orange_diamond:MRGB mode.
B. Click in canvas and ‘drag’ to ‘grab’ the canvas. A new Alpha will be added to the ALPHA Palette and a texture will be added to the TEXTURE palette.
C. Export the new texture from the TEXTURE palette in PSD format. When exporting this texture in PSD format, you’ll be presented with the following dialog box…

This image contains material-index imbedded within each pixel.
Would you like to save the material-index as a separate channel?

Press “Yes” and the PSD image will be saved with an added material-index channel.
D. Switch to the target application and import the texture.
E. In the target application…Select the extra channel that was imported with the texture. Each pixel in this mask channel has intensity value equivalent to the index number of the material that was used. In most cases, the material index value is small and therefore this mask channel may appear to be completely black. In order to clearly see each of the sections, you will need to increase the contrast of this channel (manually or by using auto-contrast).

I hope that you’ll find this useful (and not confusing) :slight_smile:
-Pixolator

Great, as usual for a GrandMaster.

Thank You

Oh, yes… very useful! :smiley:
Thanks!

Adman

Great stuff to know, Pixolator. Thanks!

Good on ya Pix!
I fiddled around with this in THIS thread, but I goofed it up by replacing the texture map with a white texture map and exporting the picture. Doh!

You export the alpha grab and the picture and composite them together correctly in PSP or photoshop. Paint Shop Pro gives the best results;- (check out steps- 5 to 8 the my thread above!) and with photoshop it can get a little “dirty” when it comes to fiber brush selecting.


In Photoshop with the select the black area and select “SIMILAR” from the select pannel to more of the small black areas selected - then save the selection with a name of your choice eg “My new Alpha”


Then with the RGB picture loaded LOAD the selection from the SELECTION-LOAD dropdown and load the alpha you just named.


As you can see the selection isn’t the best, so I recoment trying it with Paint shop Pro if you can where you can load a black and white picture as an alpha!

Thanks so much for your time spent creating this tutorial and the information!

another huge tut to add to the quicklinks pix…awesome thread …thanks

Thanks for the useful info.
Dave

As always your insight is most welcome o’ wize one of the Zeenites!

Thanks for the info! :slight_smile: I didn’t know half of it like I should have, and half of it I knew half as well as I should of. Errr… :wink:

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Thanks a lot!

Anderson Soares
gendragon

Pixolator
Thank you very much for the tutorial.
I emplyed your techniques to generate several alphas from a old model.
They make excellent stamps for base reliefs.

Attachments

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