I created a logo with a mask. I want to save it, but when I click Create Alpha all I get is a square alpha, not the design. I don’t see what I’m doing wrong, seems straightforward, draw mask > Create Alpha…
Not enough information. Alpha is created from depth information. What were you trying to get, how did you get to the ‘failure point’?
Afaik, masks don’t have depth but you can still create alphas with them. I gave you the info. The failure point is when I click “Create Alpha”, it just creates a square alpha, not the design I drew with the mask.
Case 1 (it works):
Case 2 (it doesn’t work):
Use my ExtracT plugin on the masked area to get a nice raised relief looking second part or transpose that out after inverting the mask.
Thanks, but I want to know why this method isn’t working.
Group masked, Hide rest, then grab alpha .
I had tried something similar. I hid everything except the masked area (without polygrouping), then I tried creating the alpha but nothing. I then hit “make polymesh 3d” to make a tool of just the masked area and tried to create the alpha again, but Zbrush freezes every time I try creating the alpha this way. I then exported the tool of just the masked area and tried to do this in ZB4.6, it freezes too.
I’m done.
Try to reverse the mask and then to do it. Maybe then works.
What are the UVs like? If they are overlapping then that may be the cause. I can’t think of any other reason why that’s not working.
I did get a square image here. Also faced with the button dimmed out on occasion. Maybe this is glitchy too…
When the button is grayed out you need to create uvs. I still can’t make the alpha though.
http://www.zbrushcentral.com/showthread.php?192199-Can-t-create-alpha-from-mask&p=1129199&viewfull=1#post1129199
Hide what you don’t need in the alpha and scale as desired; then go to the alpha palette and click GrabDoc. Bam, you’re done 
I’ve done that but that just captures what you’re seeing at the time, not the whole mask. Because of the shape of the chest, the mask wraps around and using grabdoc doesn’t detect that. I think using create alpha does get the whole mask.
It’s not clear to me what you want to use it for? It’s not necessary for good sculpting… You can create a group from the masked area and set Mask by Polygroups to 100. Only what you want to move will.
It’s just to save it. If ever make a design with a mask, be it for painting or sculpting, I would like to save the design for later use. If ever clear the mask, it’s gone. I would need to create the design all over again. Plus, even if I never clear the mask, which is highly unlikely, I wouldn’t be able to re-use the design somewhere else. The Superman logo is just an example, it could be a complicated design of my own.
“Because of the shape of the chest, the mask wraps around and using grabdoc doesn’t detect that.”
Overhangs don’t work.
I was able to get it to work, but the image isn’t gray scale. It’s black on white, 2 colors. You may have to do it as I suggested before and make sure you have enough polys and UV’s. I don’t know if it has issues or if we’re both unfamiliar with the proper usage etc…
It was the UVs. Thanks Marcus. Thank you too Doug. I used unwrap UVs from the UV master plug-in to fix them. The only thing is that the alpha doesn’t look like the mask, but when you apply it with “mask by alpha”, it does look like it. Is there a way to fix that? It’s more useful to have the alpha look just like the mask. For example if I want to use it with drag rectangle it won’t work well the way it is now. I know in the past the alpha did look just like the mask.
UVs are basically the way a 2D image is wrapped onto a 3D model. The more complicated the model, the more complex the UVs need to be. This often means that the 2D image looks less like a flat version of your model, as things get distorted. UV Master does a good job of making the UVs readable but you will never be able to get a result that looks just like a flat 2D image of your logo.
You’ll need to work in a different way for when you want to drag out a mask. You can create a black and white image in Photoshop. Or in ZBrush, paint a mask on a plane and then save the alpha from that.