Alpha maps are interresting as they can be used directly as sculpting tool for most (all?) sculpting softwares (Zbrush, Sculptris, 3DCoat, Mudbox, Blender, ...) for adding texture.
To do a good alpha you need a good displacement map with beautiful depth data. I highly recommend you to generate that displacement map automatically from 2 photos of the same subject using my new software Photosculpt Textures (download the 30-day trial here or buy it now from Eur 99). This has already been explained in this short 1'43'' video tutorial so I'm not covering it here again. Here I'm assuming you already have a displacement map at hand. Of course alternatively you can download the one on the left or 10 more in my free sample section (I also have a pay sample section from Eur 5.99)
Once you have a good displacement map, then launch your favorite image editing software (photoshop, Gimp, ...) and do the following:
Step by step: Open your displacement map and add a new layer to it, fill this layer with black, set it in color burn layer mode. Then paint a white circle in the center of it with an airbrush as shown. Save your image. Open it again in your sculpting software as alpha brush and start sculpting. Voila!
Here are some free samples for download. (click on thumnail to download)
...and how I use them:
- You may want to keep the alpha map size down if you encounter slow sculpting, unstable software or downsampling artefacts. I think a 300x300 pixels 8 bit alpha map are enough for most uses.
- For best effect, if your displacement map is too gray, you may want to adjust its contrast before using it as sculpting tool
- Instead of painting only a circle with the airbrush tool, you can paint more intricate details in your textures, hiding (with black) or showing (with white) areas of interest as you see fit
- You can create 16 bit alphas using the 16 bit tiff displacement maps from Photosculpt. This will allow 65535 steps from front to back, witch is nicer/smoother than the default 256 steps of usual 8 bit image formats like jpg.
- Here is a link to a good alpha community where you can download / upload your alphas: http://www.pixologic.com/zbrush/downloadcenter/alpha/
In this tutorial I've shown a new way to create photorealistic alphas.
This method is I believe superior than any other method as I used 2 photos per subject and my new software Photosculpt Textures to "scan" real objects and extract real depth data from them. It's very similar to sculpting with a stamp casted from a real object if you prefer :-)
Hoping you'll like it! Dont't hesitate to comment or improve this tutorial!