Asset Creation: Advanced Shading, Lighting, and Baking - Creating Games with Unity and Maya - page 149

It's easy to see how bump maps can be easily altered with a bit of contrast
adjustment, and even by hand painting some white areas that needed to
be rendered higher. Not so with the normal map. In fact, the red, green, and
blue normal-vector values must equal exactly 1, and if the colors are painted
by hand the values may not be what are needed and break the texture. So to
ensure these values are correct and will function in the game we will need to
use some other tools.

Additional Tools

There are some cheap and even free software packages that assist in creating
normal maps. A very nice one (and one that is reasonably priced: $299 for
Professional, $99 for Personal, $49 for Student) is CrazyBump ( http://www.
crazybump.com ). CrazyBump allows for a 30-day trial, but anyone who tries
this will quickly see how powerful and easy it is to refine a normal map from a
color map. If it's in your budget, CrazyBump is a really great time-saving tool
to add to your tool kit. Importantly, CrazyBump is available for Mac and PC
whereas the plug-ins for the next step unfortunately appear to be PC only. So if
you're Mac based, be sure to grab CrazyBump's free trial and skip this tutorial.

Warnings and Pitfalls
It has been a while since
NVIDIA updated these
plug-ins. Unfortunately
this means they
are apparently not
compatible with 64-bit
versions of Photoshop.
So, if you are using a
64-bit operating system
(Windows 7 or Windows
XP 64-bit) you will need
to use the version of
Photoshop that was
installed in the Program
Files (x86) folder—this is
the 32-bit version.

For those of you who use a PC and are interested in the free options, there
are some free alternatives (which are what we will be using for this tutorial).
NVidia has released a free set of plug-ins for Photoshop that assist in the
creation of normal maps. They are available at http://developer.nvidia.com/
object/photoshop_dds_plugins.html . We will only be using the Normal Map
Filter part of the package, but just this part is quite powerful.

Step 1: Download and install NVidia's Plug-ins for Photoshop (use the
preceding URL). The install package is a .exe, so just launch it and follow
the instructions to install.

Unfortunately, when using the default installer, the plug-ins will be installed in
the 64-bit version of Photoshop. On install, you should be able to define which
version of Photoshop the plug-ins are installed to, and if you are, just point the
installer to the 32-bit version. However, if you were not able to define which
version of Photoshop to install the plug-ins to, go to C:\Program Files\Adobe\
Adobe Photoshop CS5\Plug-ins\Filters and copy the NormalMapFilter plug-in
and paste it into C:\Program Files (x86)\Adobe\Adobe Photoshop CS5\Plug-
ins\Filters. Then, of course, launch the 32-bit version of Photoshop when you
wish to use these plug-ins.

Step 2: Select a texture to work from. I am using the texture assigned to
the EntryWayWallsInner. This texture is EntryWay_WallsInner_Color. Open
the unflattened (all the layers intact) version in Photoshop ( Figure 7.2 ).
This version will probably be within the images folder of the Maya project
file and may be labeled either EntryWay_WallsInner_Raw or EntryWay_
WallsInner_UV if you just saved over the UV snapshot. Do not edit the
version of this texture in the sourceimages folder. We need the layers.
Finally, resave this file as EntryWayWallsInnerNormalRaw .