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Brush Alpha Dark edges - Issue

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I can't for the life of me figure out how to solve this issue.  It was a bug from a LONG time ago and I remember having this discussion before but was it resolved?  I have done several searches for this issue on the forums and it comes up with nothing relevant on the first 5 pages or so.

The Issue

Custom created Alphas for the brush tool causes dark fringes around the painted pixels in the Paint room.  This problem doesn't seem to occur with the default brushes.

To reproduce the issue

  1. Create a custom alpha (I tried with tga, png with transparency)
  2. drag alpha image into 3DCoat window and choose 'create new Alpha'
  3. create a layer and fill with black
  4. create a new empty layer and paint white pixels with your new brush 
  5. continue painting and overlapping the same spot with white pixels and note that there are dark spots around the fringes of your 'white' alpha in the brush


As I said this is an OLD issue but I cannot for the life of me remember how to resolve it.

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On your created alpha, the HeightMap layer... have a background grey value of R,G,B = 49.8 ?

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The HeightMap layer is 50% Grey  (RGB 128,128,128)


Should it be 49.8% Grey?


By the Way I'm only painting RGB and not Depth or Metallic/Roughness 

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Will you share that brush to take a look please ?

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create and share 3dcoat extension with the brush that you have troubles, yes please. Thx.

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Brush Components - Alphas

3D-Coat’s Brushes can be given a “profile” by means of the brush Alpha panel.The term Alpha is common amongst 3D sculpting and painting applications wherein the alpha is a simple greyscale image. However in 3D-Coat they consist of four painting channels:

  • Color
  • Height/Depth
  • Glossiness
  • Erase Mask

So each Alpha can paint multiple channels at the same time, if you choose to. Making them less an Alpha and more of a multi-channel image brush tip. We maintain the term “alpha” to keep with the industry standard terms.

Alpha Right-Click Options

Brush Components - Alpha RMB

Right clicking on any Alpha will display editing functions for the respective Alpha. Brush Options opens the “Brush Options” panel. Delete Alpha deletes the selected Alpha. Save to PSD/TIF saves the selected Alpha to the chosen format file format to a directory on your computer.

Load from PSD/TIF replaces the alpha that has been right clicked on with another image of your choice, as long as it is PSD or TIF. An Alpha must have 4 layers each corresponding with the four main channels of a brush in 3DC (as noted above, they are Color, Height/Depth, Glossiness & Erase Mask). These channels of the Alpha in detail are:

  • Color: This contains the Brush color as well as its corresponding Transparency mask. This mask affects the Glossiness Layer, as well.
  • Height/Depth effects displacement for sculpting and the height/depth with image based painting. The “zero” height of this Layer corresponds to “middle gray” or (127, 127, 127). Darker values will create valleys and lighter values will create peaks.
  • Glossiness: White represents maximum Glossiness. Black represents absolutely no Glossiness, with shades of gray representing intermediate values. The Color layer of the Alpha’s alpha transparency also determines where Glossiness painting occurs.
  • Erase Mask: This layer is used to create alphas that ignore certain values, in other layers, while painting.

If all the .TIF channels are used, they will all be imported and used according to the table below. If you only use some of the available channels, those you do import will also be used according to the table below.


1 CH: A&H
2 CH: 1 – A 2 –H
3 CH: 1, 2, 3 – RGB, 2 – A, H
4 CH: 1, 2, 3 – RGB, 4 – A, H
5 CH: 1, 2, 3 – RGB, 4 – A, 5 – H
6 CH: 1, 2, 3 – RGB, 4 – A, 5 – H, 6 – Spec
7 CH: 1, 2, 3 – RGB, 4 – A, 5 – H, 6 – Spec, 7 – Erase mask

Edit in external editor: Creates a “live” connection between 3D-Coat and the external editor you have specified in the “Preferences” section. The default editor is Photoshop. Selecting this option opens the specified editor and any changes that you make and save from the editor are automatically loaded back into 3D-Coat.

Edit as 16 bit TIF: This allows you to save in 16 bit format, rather than 8 bit. Using this option causes the Brush alpha to be saved as a .psd file, allowing it to be reloaded automatically, each time it is edited and saved in the external editor.

–>default (etc.): This option will allow you to copy the Alpha that you right-clicked on, to a folder named in the folder list that you have previously defined. All the folder names you have defined will appear here.

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